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Discussion Starter · #121 · (Edited)
Might be too late but if you're still considering reworking the system, I went w/ a fuel vent barb for my breather hose.


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Interesting solution. So far so good with my screen gasket after a long drive today and plenty of bumps with not a drip anywhere, even with the tank totally full. Any pump works perfect, tons of pressure.

Cheers.
 

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Discussion Starter · #122 · (Edited)
I've been experimenting with the van in deep off-road sand lately, and a forum member asked for some photos.

Before I get to that, I've found 54 psi front and 65 rear (cold pressure ~ 35F, I may change these in the summer) is about perfect for my build (2020 148 AWD) at its current weight (~6500lbs) for both highway and general off-road. If road conditions are really bad or I get stuck, I plan to try subtracting -10 front and rear from those values. That should happen eventually since I tend to take risks a lot. But in the meantime those values are working well to improve ride comfort and help in deep sand.

So, here is some info on a section of Death Valley that is the only place I've ever been stuck. I was in my old FWD SUV, forgot to turn tcs off, it braked me to a stop even though I had made it through there many times before (with rocks crashing into the undercarriage due to only 7" clearance). I was also getting ready to sell the suv so I had replaced my yokahoma AT's with dirt cheap china m/s tires from Amazon.

Anyhow, downhill is much easier than uphill, so I'll document the uphill route. I've successfully traversed it both ways using mud/rut mode (automatically disables TCS) in manual 2nd gear doing 10-15 mph with moderate to hard pressure on the accel pedal and rpm's in the 2k-3k range. Gentle boatlike adjustments when drifting to one side, increase accel pressure when losing momentum. Hard to tell in the photos but there's a 5-10 degree grade to the entire landscape).

First you get a 30 foot teaser section with ~3-4" silty smooth sand. There had just been a three day windstorm so the tracks were also leveled out considerably.
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If you try the usual tactic of maintaining speed/momentum you get a nasty surprise every 50 feet or so when you slam into brief 5 foot hardpack rocky sections. Can't just go around because the road pinches in places, with big buried rocks people have hit and pushed off to the side.
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Looks like someone punctured their oil pan on a rock and drained out.
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Then you get two more mild sections similar to the first and interrupted by another very short hardpack rocky pinch. Then you finally hit the real stuff.

When someone asked in another thread how long the sand was I just remembered going fast to get through it so I said 20-30 feet. Turns out the worst part took two photos to show it all, so I now think it's more like 100+ feet for those two sections alone. And again, this is after a serious three day windstorm that leveled the tracks.
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The side of the road is way worse. People who have tried to go off there left tracks that are filled with powdery sand that your foot just sinks into, and the bushes and rocks pinch you back on the road in a few feet anyways, but now you've lost your momentum. What's also hard to picture are the buried rocks. They're everywhere, as drivers before have found the hard way. In a stock AWD van even with slightly larger AT tires I suspect your differential and shock mounts would take a beating, just like my old SUV always did (7" clearance on that one). If I recall the oem shock mounts are a mere 5.5-6.5".

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If this were just pure sand like a beach, no problem, just run and gun, but the buried rocks, the uphill grade, and the sudden rocky hardpack areas make it a jarring ride in a van with tv's, refrigerators, dishes, inverters, battery banks, etc.

But all told this is actually not that bad. I chose it for testing because I was already fairly sure I'd get through it. But I'm glad to have AWD, shock mount edit, upgraded suspension, and the lift kit/big tires with higher ground clearance. It makes a real difference out here, even if they may cause problems (see first post in this thread).

Cheers.

Update: even after a windstorm that completely filled the tracks with insanely powdery sand, the Transit still made it through in the uphill direction, although it took much more power (pressure on the accelerator) and my speed got as low as 8-9'mph on the dash or 10-11 mph accounting for the larger tires. But that was probably the worst sand conditions this van will ever encounter.
 

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Discussion Starter · #123 · (Edited)
Well, the fun and games are over and it's back to building...and building...and building. It never ends. Part of me is happy about that, since it's engaging nerdy work that offers tangible results after each's day marathon. But the rest of me is ready for it be over so I can get on with enjoying the RV.

Next up is the power system. I had a temporary system, which may serve as backup, running off the van's dual AGMs, but the 356lb 20kWh 48V lithium bank arrives on Monday, so I had to get busy preparing for it. I've been sourcing and wiring up my AC and DC switchgear (more on that later), and I temporarily removed the adjustable bed so I can work on the location for the inverter install.

Today's project: adding a discrete 120/240 50 amp twist lock power plug.

I'm trying to minimize external signs of a campervan, so I located the plug under the van, in front of the rear tire (was the only viable spot). I used an aluminum project box (lots of ideas for under-van mounting came to mind after finding this solution), cut mounting holes in it, and bolted it on with my usual stainless hardware with nordlock (required one 5/16 and one 1/4 bolt/nut assembly to use existing frame holes). Then I added a 90 degree 3/4" non-metallic liquid-tight "carflex" terminator on the project box lid, and ran 3/4" carflex conduit (sourced from my local electrical supply house) into a slightly dremmeled out 1" hole drilled into the underside wall, and ran the conduit up through a similar hole in the interior sidewall floor. As usual, came back later and touched up everything with rustoleum, and sealed the hole edges with clear silicone.

I pulled 4 x (red, black, white, green) 8AWG 200C-rated silicone-jacketed tinned copper lines through, and wired it up to my twist lock plug, then screwed the project box lid on until it was as close to water-tight as it was going to get. I debated a lot about 8 AWG versus 6 AWG, but I'm very glad I went with 8. Not only is my expected continuous load so low that even 30A split-phase would be overkill, but with fine stranded tinned copper, at 8 AWG I could barely fit it into the 50A plug terminals.

With a 200C rated jacket I can use the NEC 310-16 90C current rating of 55A, even if 50A is more commonly wired with 6 AWG copper. Yes, the connection-points are typically not rated at 90 C (more often 75 or 60C), but in a fault scenario the main service panel breaker would trip in milliseconds, long before 8 AWG even got warm, and it's a very short run to my AC switchgear's 30A downstream breaker.

Again, my anticipated continuous current is so low that all of this is overkill in some regards. I'm only doing it since RV parks only offer split phase on 14-50 outlets, and I need 240V for a planned high efficiency minisplit (40+ SEER). Quite often I'll actually only bring in 120V 15A on a single hot line connected via extension cord to a friend or family member's outdoor outlet because my inverter has a nifty trick up its sleeve: it can auto transform 120V into 120/240V, and it will supplement power from the battery bank if a startup load exceeds the capacity of a single 120V 15A input. That should come in handy anytime shore power is lacking. And I probably don't even need shore with the planned solar and alternator combo, but for long periods parked at home, I'd like the A/C unit to run off the house power and avoid unnecessary cycling of the lithium bank.

Cheers.

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1/5/21 UPDATE: As discussed on page five of this thread I experienced a steering fault and a warranty rack and pinion replacement. There is a Ford Communication about this issue and it specifies the exact fault code I had, so this issue may be unrelated to the lift kit, but always do your own due diligence. Having said that, the service manager at my local dealership claims the larger tires were somehow "confusing the gears" in the power steering system, but they also claim they fixed it by adjusting settings so that the van knows it has larger tires. They said I should be fine from now on, but my speedometer is still off (normal with larger tires) so I'm still trying to determine precisely what settings they supposedly changed. I personally think it was a faulty sensor which the Ford Communication appears to suggest. I've offered the service manager $100 and a case of beer if he'll have the tech call me so I can try to get more info.

Original Post Aug 2020:

Finally got the van back from the lift kit installer. Major props to Van Compass for coming through on the 3/16" front spacers needed to fit 265/75/16 Terrain Contact A/T tires. You guys rule! (They recommend doing the lift kit trimming step on stock tires, then taking it to a tire shop and test fitting one tire).

So far it rides really smooth, much better on bumpy sections, no issues whatsoever using the Van Compass red spring on an empty van. Glad I got it versus the blue since it can accommodate a heavier build later on.

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I asked the installer not to trim the external plastic so I can see what I can get away with. Also had him do the smallest possible pinch weld trim, but on one sharp fast u-turn I got a little rubbing at the seem. I'll likely flatten it as others have done. Probably should have just let him cut more, but I like how the outside looks unmodified. Someday in mud or snow I'll want more room, so I may trim the outside after all. Angle grinder/cutter will make quick work of it.

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Continental specs their 265/75/16 at 32.2" diameter but I believe all or most diameter specs are listed at 80 psi unloaded, so you don't get as much extra clearance as I'd hoped, but the more I look at the skid plate the more I'm convinced that was a good move. It's rock solid, and I'd be fine with it skidding up and over an 8-12" rock at 5mph. I'll measure again once the build is finished, but either way, it's still much better than it was at stock. Shock mount edit looks great too. That one is a no brainer.

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Front side of skid plate (same 12" when re-measured on level concrete):
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Back side re-measured on level concrete, right at 8.25" with skid plate on empty van (will likely drop to 7.5" after the build, but now I can impact the plate):
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Angle of photo is off, but notice how clean they look afterwards:
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Shock mount clearance (no longer the low point -- nice):

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(Continued)
Beautiful rig, curious who did your lift kit install and how much did it cost you?
 

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Discussion Starter · #125 ·
Beautiful rig, curious who did your lift kit install and how much did it cost you?
Hi 21Eco,

Seeing as you just joined the forum 2 hours ago, and we do get scammers on here, I'm a bit cautious discussing anything money related. But you can easily get quotes locally by calling the installers listed on Van Compass' website. One or more will likely be close enough for you to drive there. If you call a few and say you are looking for the lowest price and are comparing with two others, you'll probably get a good deal. I hope that helps. Thanks for the kudos.

Cheers.
 

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Discussion Starter · #126 · (Edited)
20kWh of lithium batteries arrived today, and @njvagabond asked about them, so I thought I'd do a quick post. I've been working like crazy. Lost a week helping my sister move, so not as much progress as I'd like, and there are so many projects going at once it's hard to document them since they're all interrelated and none are fully finished.

But here's a taste of the forthcoming power system:
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You know when you order by the crate you either got a good deal, or you're just plain nuts.

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The throw-away plastic cover on the capacity indicator is just ruffled up from the ample Styrofoam packaging they used for shipment. The display underneath is pristine, and the batteries are shipped at about 1/3rd SoC for safety and longevity. The nylon screws on the terminals are intentional because the case is isolated from both sides (a very good thing). I've obscured the model number of the packs for the time being. Once I've tested them and found they matched the quality of the sample cells the manufacturer sent me last fall, I'll post more about them and provide links. I've made some good relationships in the process of sourcing these custom packs, and if by chance I'm not happy with them, I don't want to throw dirt on the good people I've worked with. But I don't recommend things just because I bought them.

Each battery is 5.12kWh, chemistry is the safest LifePO4, in an IP66 aluminum case, weighing in at 89lbs, and the dims are 17x10.5x10 (L/W/H). Terminals sit 0.7" above the top so 10.7-11" H including lug and 5/16 bolt. Busbars are aluminum, so that cuts down on cost and weight, but does add some resistance. Prismatic cells also pack down much smaller than cylindrical cells like battleborn, so you can fit a lot more power in a smaller space. But again, that too impacts heat dissipation.

However, the packs are designed to do 1C discharge and charge all day long. With four packs in parallel, my per-pack C rate will be tiny. Like 0.1C or less, so that should take care of internal pack heat concerns. The real issue is living in and preferring hot places. When it's 110F out, even with the best venting/fan system on the planet, it'll be 110F in the van. Most lithium batteries start cutting out at 122F, and it's often 10F hotter even if a well-ventilated van if its parked in the sun, which it will be to take advantage of solar. But the whole point of this much power is for off-grid a/c, and when I'm visiting family, I'll just plug in an extension cord and run the a/c off that to avoid cycling the lithium bank.

Off-grid heating is easy, cooling is hard. Heating took a few hours and about $100 to solve. Cooling is a never-ending multi-thousand dollar project I'm working on for the entire van.

For heating, I put some 13.5V Facon heat pads (Amazon) that match the pack size (with minor trimming) on a layer of minicell, and all I need to do now is wire them up to the MPPT's aux relay that has a programmable temp sensor trigger. The pads are self-regulating (turn on 45F, off 68F +/-5F) but I may want to cut off heating earlier. Low side temp is about perfect since the packs cut off at 36.5F +/- 4.5F, so hopefully that's close enough to prevent a cutoff.

The batteries gain both vibration damping and insulation from the minicell, and my floor is already very well insulated, but heat rises, so in the winter I may need to create vents on the battery compartment that can be closed. We'll see.

The minicell really came in handy as a baseplate to keep the pads all aligned to the exact location I want each pack to reside.

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The space between the pads is to account for the air gap I've left between the packs. That will allow them to dissipate heat easier in the summer.

Njvagabond asked about import/export issues, and I had none. The U.S. importer I work with has been around for decades, and is known as reputable. The manufacturer he works with is led by a guy he's known for 10 years and considers a brother. They can source cells used by a major US auto maker in their electric cars because the giant plant that produces the cells is in China, and the guy who runs the company that built these packs has connections there. His company can purchase and use the cells to build packs as long as they don't publicize the auto maker's name or state any kind of affiliation (no it's not Tesla). I've traded hundreds of emails with the manufacturer and his engineering team, and that's helped to build up some trust. But I'll believe it when I see how they perform during this upcoming hot summer (it's gonna be a scorcher).

The cells they sent me were rock solid, low IR, low self dissipation, and capacity was spot-on. Welded busbars eliminate the risk of rattling off, making these packs ideal for mobile applications. I've been told they have undergone rigorous vibration testing, and this is one of the reasons for the sealed IP66 aluminum case. While it doesn't vent like some rack-mount lithium packs with internal fans, it also provides greater stability, and it keeps our dust and especially moisture, which is a known killer for LFP cells in particular. Hopefully the packs are every bit as good as the sample cells they sent.

The bulk of the lengthy discussions I've had with them revolved around adding some safety features to the BMS to help mitigate the risk of a cutoff while charging from a rotating power source (e.g. an alternator). The system we developed isn't perfect, but it's miles ahead of a pack with no BMS communication and still costs much less, around 1/3rd the price.

With a single battery pack, an unexpected BMS cutoff while charging via the alternator is a real concern if you're at 48V. They make these exact same packs at 12V and 24V, also with the same new comm features, and you can buy one-use (or a few uses) inexpensive alternator protection devices for those voltages, so it's not quite as important for them, but it's still good to have comms. Having your battery tell the alternator to power down is far better than buying and replacing Sterling devices.

But 48V is still so new that there is no SAE standardized alternator protection device, so the only solution is a smart BMS that can communicate with the alternator's regulator. Why does this matter? The physics of 48V rotating power and a sudden BMS disconnect from a single battery pack is staggering. You're talking 280V and 4-5 kilojoules. It happens because the alternator has magnetic energy stored in it, and it takes time (~2 seconds or less to be exact) to dissipate that energy. If a battery cuts out, there is suddenly no path for the high charge current to flow, and as current plummets toward 0 amps, power is still high, so voltage spikes. That can destroy the alternator, your inverter, and anything else connected to them.

Interestingly, it's estimated that if you have even a 5% (of the charging current) load attached in parallel with the battery bank (e.g. inverter or other house loads), you may be fine because the current never falls toward 0, so voltage doesn't spike as bad. If charging at 5kW, even just 250watts of load may be enough to prevent the worst of the spike. But it's still not good, and something you want to avoid.

With multiple packs in parallel, the odds of all four packs going into a BMS cutoff at the same instant are very low. And you can design your system so that if even one pack goes offline it triggers an alternator shutdown procedure. That lets you stop and asses what's going on and address it before restoring alternator charging. With four packs, and with the new BMS comms that will alert when temp, cell volt, or current are approaching BMS cutoff conditions, the odds start getting lower and lower.

But it's something to be aware of if you're a 48V enthusiast. There is no ultimate fail-safe like you have for 12V or 24V aside from adding a small bank of 4 x 12 = 48V AGM UPS batteries at 10% (or more) of the total lithium bank size. UPS batteries can handle higher charge currents than scooter batteries. This "keeper bank" is wired in parallel with the lithium bank, and you have to replace it every so often. I might add it for peace of mind, but I'm not certain it's necessary, so more on that later. Sticking to 24V would be my recommendation for most people.

So why am I doing 48V? First off, the situation described above should be exceedingly rare or never in a well-designed system. Usually it's an aging system with only one pack where it crops up. Second, with the batteries at 48V, the alternator at 48V, the inverter at 48V, the solar array at 140V and the MPPT charging at 48V, my efficiency is going to be very high. And the primary goal of this power system is to have it run a 40+ SEER ultra-high efficient minisplit a/c unit. I like a/c. That much. The more efficient it is, the longer I can go before needing to idle the van, which won't generate as much power if idling somewhere hot (alternators reduce output when they heat up).

And if you consider the fact that in the peak summer months even a 40+ SEER minisplit could draw 5kWh or more per day, while my DC house loads will often be a mere 250 watts over the same period, it starts to make a lot of sense. Even small improvements in efficiency along the path to the minisplit produce dramatic gains compared to any small losses from buck converting down from 48V to 24V or 13.8V. A 10% loss (exaggerated) on 250watts is a mere 25watts. But even just a 2% gain on the inverter efficiency from being at 48V instead of 24V = 100watts saved from the a/c load. Multiply those both by 24 hours and it starts adding up: 600Wh lost versus 2400Wh saved = 1800Wh net saved per day.

And the real kicker is 240V for the a/c unit, although you can go that route with a 24V battery bank. But just for kicks, the best 120V minisplit you can get is 32 SEER. The best 240V you can get is 42 SEER, and the same plant that makes it also makes a half-cost 40 SEER unit you can rattle to death for 5 years then replace with a new one. So even comparing 40 SEER to 32 SEER, you're still talking a 25% gain. That's massive for a system where a few percent is normally a big deal.

So there's a real upside to it all. Either that or I'm just a power nerd who wants build a monstrosity. There's always that possibility.

Cheers.
 

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But it's something to be aware of if you're a 48V enthusiast. There is no ultimate fail-safe like you have for 12V or 24V aside from adding a small bank of 4 x 12 = 48V AGM UPS batteries at 10% (or more) of the total lithium bank size. UPS batteries can handle higher charge currents than scooter batteries. This "keeper bank" is wired in parallel with the lithium bank, and you have to replace it every so often. I might add it for peace of mind, but I'm not certain it's necessary, so more on that later. Sticking to 24V would be my recommendation for most people.

So why am I doing 48V? First off, the situation described above should be exceedingly rare or never in a well-designed system. Usually it's an aging system with only one pack where it crops up. Second, with the batteries at 48V, the alternator at 48V, the inverter at 48V, the solar array at 140V and the MPPT charging at 48V, my efficiency is going to be very high. And the primary goal of this power system is to have it run a 40+ SEER ultra-high efficient minisplit a/c unit. I like a/c. That much. The more efficient it is, the longer I can go before needing to idle the van, which won't generate as much power if idling somewhere hot (alternators reduce output when they heat up).


So there's a real upside to it all. Either that or I'm just a power nerd who wants build a monstrosity. There's always that possibility.

Cheers.
Of course 48 volt is a good choice. Was there any doubt?

I agree with you though, the details of implementation are somewhat "non trivial".

For the typical DIYer / casual van power users, 24 volt is a better / easier solution and it is easier to find related components.

12 volt battery packs? :rolleyes:
 
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Discussion Starter · #129 · (Edited)
Of course 48 volt is a good choice. Was there any doubt?
The doubt is centered around 48V for both the battery bank and the alternator. With series (e.g 4 x 12V series) or only one 48V battery that doesn't have a BMS with pre-cutoff signalling capability, it's a disaster waiting to happen. There's not only doubt, there's very real risk.

If I recall (please update me if this is old) you're using 48V banks but 12 or 24V alternators for which there are readily available protection devices, and you're boost converting up to 48V to charge the batteries. The problem is converting a high-power pathway, be it for charging or a large load, means a lot of unnecessary loss. A 10% DC boost conversation loss on a 5kW alternator is 500 watts per hour of charging lost, so it really adds up if you idle or drive for 3-4 hours to charge the bank. That big charging loss offsets most of the gains from being at 48V, so you might as well run a 24V battery if your alternator is 24V. Granted DC boost/buck converters often have peak efficiency higher than 90%, but not when it's hot, which is when you need power the most for an a/c.

While 48V rotating power removes that loss, it's a different beast. It keeps me up at night working through the failure modes, and I very well could burn up my inverter and alternator someday if the system for alerting the alternator to power down somehow fails.

Even so, it's good to have you on the forum as another 48V proponent. Let me know if you ever install a 48V alternator someday. I'd love to compare notes on how you decide to approach load dump protection. There is no SAE solution yet aside from keeper batteries or a smart BMS, and even with a smart BMS, shorting the battery bank with a large conductor may still trigger an instant cutoff if current goes high enough, so there's still risk.

Cheers.
 

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The doubt is centered around 48V for both the battery bank and the alternator. With series (e.g 4 x 12V series) or only one 48V battery that doesn't have a BMS with pre-cutoff signalling capability, it's a disaster waiting to happen. There's not only doubt, there's very real risk.

If I recall (please update me if this is old) you're using 48V banks but 12 or 24V alternators for which there are readily available protection devices, and you're boost converting up to 48V to charge the batteries. The problem is converting a high-power pathway, be it for charging or a large load, means a lot of unnecessary loss. A 10% DC boost conversation loss on a 5kW alternator is 500 watts per hour of charging lost, so it really adds up if you idle or drive for 3-4 hours to charge the bank. That big charging loss offsets most of the gains from being at 48V, so you might as well run a 24V battery if your alternator is 24V. Granted DC boost/buck converters often have peak efficiency higher than 90%, but not when it's hot, which is when you need power the most for an a/c.

While 48V rotating power removes that loss, it's a different beast. It keeps me up at night working through the failure modes, and I very well could burn up my inverter and alternator someday if the system for alerting the alternator to power down somehow fails.

Even so, it's good to have you on the forum as another 48V proponent. Let me know if you ever install a 48V alternator someday. I'd love to compare notes on how you decide to approach load dump protection. There is no SAE solution yet aside from keeper batteries or a smart BMS, and even with a smart BMS, shorting the battery bank with a large conductor may still trigger an instant cutoff if current goes high enough, so there's still risk.

Cheers.
You are exactly correct on the challenges and your list is accurate.

I have worked with the 48 volt alternators on the sprinter platform but not the Transit platform. You are definitely breaking new ground on the Transits and that pack size.

You are also correct that there is no perfect solution, and that there are challenges on both the large battery packs, but even greater for smaller battery packs. ( ~ 5 kW-hr size). Especially before the availability of the wakespeed controller, small 48 volt packs, charged from a 48 volt alternator were a massive problem.

I have actually asked alternator suppliers to instead build 60 amp / 48 volt alternators vs these 2x size ones as the control would be much easier. (no luck so far).

You are right - I have invested a lot of money and testing time into 48 volt product development, including hiring additional engineering resources to help check / change things.

It is why I happily help people with 12 / 24 volt systems on line but don't say much about the details of what I have done in 48.

My main advice is to set the settings to charge the pack slightly less than absolute max where there is risk that the bms will trip.
 

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Discussion Starter · #131 ·
settings to charge the pack slightly less than absolute max where there is risk that the bms will trip.
For sure. The packs also have comms that are less than the max for a bms trip, but that's a last resort. The first resort is just programming the regulator, mppt, and inverter charger to leave a buffer. Temp is the most common issue, and the packs even have another set of pins that trigger heat/cool signals at even lower/higher temp thresholds.

I know you've made a business out of it and have done a lot of work, so I understand keeping secrets close to the vest. I'm just in it for the fun, so I tend to "let the information run free" and think opensource on everything.

Cheers.
 

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Van Gogh, just to say, I really have enjoyed reading your 48v build, and will eagerly wait to hear how you solve some of these steps. I've ordered a 148 extended AWD EcoBoost, and would like to build a large battery pack with a direct charge to an aftermarket alternator. I'm planning for 24v right now, but if you have luck with the 48v, would step up to that! I'll be doing full-time living in the urban (and cold!) midwest, so I don't have these intense heat concerns and am looking to go without solar panels altogether, if possible. Thanks for all the info on here! and good luck!

PS would love to know the factory you worked with for the pack. Think you might be waiting to see how they operate?
 

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Discussion Starter · #133 · (Edited)
Van Gogh, just to say, I really have enjoyed reading your 48v build, and will eagerly wait to hear how you solve some of these steps. I've ordered a 148 extended AWD EcoBoost, and would like to build a large battery pack with a direct charge to an aftermarket alternator. I'm planning for 24v right now, but if you have luck with the 48v, would step up to that! I'll be doing full-time living in the urban (and cold!) midwest, so I don't have these intense heat concerns and am looking to go without solar panels altogether, if possible. Thanks for all the info on here! and good luck!

PS would love to know the factory you worked with for the pack. Think you might be waiting to see how they operate?
Hey prairie, thanks for the props. I feel like a mad scientist right now, seriously. Am I going to kill myself? Burn down the van? A forest? But then there's the thrill of rigging up this monstrosity. The nerd in me is alive and kicking.

I do believe 48V is achievable with these packs, and a variety of other safety measures, like ensuring that any one pack going into a BMS cutoff instantly disables alternator charging. That's the key backup, since 4 packs in parallel means I'll have 3 other keeper batteries. Even if two or three went offline within 2 seconds, having just one left is all it takes to avoid any problem. Plus the alerts that should provide warning, plus the regulator itself detecting adverse conditions, all together it should be safe as long as all systems perform as expected. I bet the first few years will be fine, but 5-7 years from now when heating/cooling and old componentry start going wacky is when I'll need to be vigilant, and possibly replace some relays. But more likely I'll have already just bought a 48V open circuit protection device which should be available by then. Balmar says they'll have one ready next year.

If you don't need 48V for a/c, I'd strongly recommend staying 24V for the time being.

As for the packs, indeed, I don't want to rush to recommending them until I have them fully nailed down in terms of the alert system functionality and testing to confirm they have similar behavior to what I witnessed when testing the sample cells. Batteries are a big investment for van builders, so if they aren't up to snuff, it's a huge setback. I am 80% confident they are, but I'd really like to go through this summer with the system fully functional before asserting that they are worth buying.

In cooler climates with no a/c at 24V and low C-rates with an alternator protection device (Sterling) in the system, I'd be 90% confident in them already, especially if you have at least two packs so one can serve as a keeper battery to prevent your Sterling device from being zapped and needing to be replaced (very low but real odds of happening, probably in a few years, not at first, unless you abuse the packs), so if you want to take the remaining 10% risk on your own, I may be okay with revealing the source in an offline message.

Just be aware the new Pro packs require a fair bit of electrical know-how to take advantage of their new features (I'm still developing my system for that), although at 24V with a Sterling device, you don't really need those features as much aside from the heating pin + relay system to warm your packs in the winter. And even that may be unnecessary, since it looks like self-regulating RV tank heaters actually activate around the charge temp alert system threshold (~41F). For discharging you can go as low as you want, although it's not advisable to discharge below 14F and the lowest you'd want to go at a very low C rate (0.05) is -4F.

But I really don't want the source info "out there" until I've tested them thoroughly, because it may get passed along, and others may not get the warnings and safety discussions I can provide in this thread, so I'd only share that info with sincere assurances not to pass it along. I personally recommend waiting until you need to order them (or 7 weeks before if you want the lowest price since shipping from the US warehouse costs more).

Also note that the price is still very good for what these packs offer and much lower than anything like battleborn, but the vendor got excited about the new packs and the potential interest from my passing along these details, so he appears to have upped the price for all of the packs he sells. Ahhh capitalism, never a missed opportunity to make a buck.

But the vendor/importer is a good guy. I know him personally now, and at 86 years old with decades of experience, he's not even really in it for the money anymore. I think he just likes what he does.

Cheers.
 

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Discussion Starter · #134 · (Edited)
It's been another busy week. Working on "high voltage" wiring and the AC switchgear.

First off, running 240V (L1 and L2 hot + GND) 200C-rated silicone jacket fine stranded tinned copper wire to the driver's side rear door for the minisplit a/c unit. 10 AWG is vastly oversized for this application (240V 15A) but I chose it due to conduit derating, the extreme heat that the rear door is subject too in full sun on a 115F day (common in late summer in AZ), and more importantly the concern that repeated flexing could eventually cause some strands to break in a few years.

I could have gone as low as 14 AWG, nearly went with 12 AWG, and after I see what wiring the minisplit sends back to the indoor unit (gets its power and signaling from outdoor) I may still have to. I haven't been able to get a clear answer on that yet, and I don't want to buy the minisplit until I'm ready to install it. I have too many things piling up in the garage as-is. I can always splice 14 or 12 AWG into the larger 10 AWG if necessary.

I used 1/2" carflex conduit bought at my local electric supply, ran it from the driver's side wheel well area where the AC switchgear will reside, back into the D-pillar, then up to the opening for the 18C618 rubber flex conduit. You have to buy the full 18C394A wiring set (~$50), then remove the OE wiring to end up with just an empty 14603. See illustration and photos. Fortunately I didn't order rear speakers so this part was not installed, which is good because I need all the space I can get for the a/c wiring. I laid the 10/3 wires flat next to each other and used Tesa heat tape (love that stuff) to wrap them that way so they round the tightest part of the bend at the best possible angle.

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I also left a small 16 AWG (orange) wire that I'll use to help pull the minisplit return wires back through when the time comes. You can also see a second 1/2" conduit that runs up the d-pillar and exits near the top. That carries two 10 AWG (same specs as always, 200C silicone fine stranded tinned copper) up near the roof for the 140V solar array that will get installed later. It also routes to the driver's side wheel well for the MPPT.

The switchgear is the heart of the AC side of my power system, and has some nice features. First a photo:
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Incoming 4-wire 120/240V split-phase shore power has 2 hots (L1 and L2), 1 neutral, and 1 ground, which arrive via 3/4" carflex from under the van where its fed by a 14-50 twist lock receptacle (see earlier post). The switchgear comes with four pre-installed busbars (not pictured) and three pre-installed 2 pole breakers.

Starting from the far left, both AC IN and BYPASS are 2 pole breakers. Each has an L1 and an L2 input. The two L1's and two L2's are electrically connected in parallel via a pre-supplied terminal tie (not pictured). That leaves you with just one L1 and L2 input. These inputs are then fed by the two incoming 8 AWG shore power hots (L1 black and L2 red).

With shore power hot supplying both AC IN (to inverter) and BYPASS (direct shore to house loads), the inverter can still charge the batteries while house loads are directly powered from shore. This works because BYPASS can only be active when the next set of 2 pole breakers, AC OUT (from the inverter), is off due to the handle interlock (chrome looking mechanism). It also means if the inverter is out of commission for any reason, or just fully shutdown, house loads can still be powered via shore.

AC OUT is fed from the inverter, and both AC OUT and BYPASS (fed from incoming shore) also have a pre-supplied terminal tie that combines their outputs into a single set of L1 and L2 outs, which are each wired to a busbar at the bottom of the case. The interlock ensures that only one or the other is feeding the busbars, which then feed other breakers, which finally feed house loads.

But most of the time I'll have BYPASS off, with AC IN (shore to inverter) and AC OUT (pass-through from inverter) active. That will let the inverter charge the batteries, qualify and pass AC through via its internal switching and signal conditioning circuitry (steps up 120V to 120/240V), and even supplement large loads from the batteries if shore power isn't enough.

One note is the switchgear came with a 60A BYPASS breaker which makes sense for residential applications, but in my case it feeds lower amperage breakers, so no more than 30A ever leaves the case.

Next, the HVAC breaker is 2 pole 240V 15A for the minisplit (L1 and L2 output, ground, and no neutral); routes to D-pillar and rear door per above.

Next the MCRWVE breaker is 15A 1 pole and feeds a 700W output microwave (1100W input measured) and any other small kitchen appliances via a 10 ft. 10/3 15A power strip (1800W) with 800 joule surge protection and plug covers to keep dust and spills out. The 10ft cord is routed through conduit to the switchgear, the plug is removed (cut off), the wires are stripped, tinned, and then fed directly into the breaker (hot), and neutral and ground busbars. I don't use a coffee machine or really anything else big in the kitchen, so 1800W is plenty for my needs.

Finally the HOUSE breaker is another 15A 1 pole that feeds two similar 10/3 15A 10 ft. power strips, one to the front of the van mounted behind the driver's seat, and one that I previously routed under the floor to the passenger side (6 months ago!). Using power strips means there are no metal electrical boxes to hookup, free surge protection, and I have tons of outlets. Seriously, I don't need this many outlets. I'm just a power junky.

The only thing of note is that I intentionally did not use GFCI breakers/inline devices/outlets/power-strips. While GFCI is (nowadays) required for code, my experience with GFCI is that nuisance tripping is too common, especially since I use a lot of power tools and they tend to leak enough to trip GFCI circuits. Others should not follow this advice and should use GFCI per code. Many RV parks are implementing GFCI at the source per updated code requirements, so I may get this protection even if I don't want it.

Lastly, G+N SHORE BOND is a 120V 60A electrodepot 2 NO 2 NC contactor. This is for the ground to neutral shore bond which my inverter doesn't supply (it's primarily intended for residential but offers features I wanted like autotransforming 120V to 120V/240V). I simplified things earlier by saying the incoming shore power L1 and L2 hot went directly to the AC IN and BYPASS terminal-tie input. That isn't quite true.

L1 and L2 hot are actually wired to the 2 NO (normally open) contactor inputs, and a small jumper ties one of them (L1 hot) to the coil input. That way even if I'm using an adapter to feed my the 14-50 receptacle under the van from a 5-15 everyday 120V 15A power plug (L1 hot, neutral, ground), L1 will still trigger the coil to close, and will pass power through to AC IN and BYPASS. This is only needed because the contactor may fail someday, and if it fails, it'll likely fail open, so the NO's won't allow power to pass until I replace it and thereby restore the ground to neutral bond.

The real purpose of the contactor is to make and break that bond. The pre-supplied (bottom of switchgear) ground and neutral busbars are each fed by incoming shore ground and neutral respectively. One wire from each busbar goes to one of the two NC (normally closed) terminals. While not on shore power, the normally closed connection makes the ground to neutral bond. But when shore power is connected, the coil is activated and NC opens.

This is critical because once on shore power, the ground to neutral bond takes place back at the main AC power panel at an RV pedestal or friend/family member's house. Without a contactor (or an inverter's internal circuitry) to break this bond, shore power return current would travel over BOTH the neutral and the ground wire back to the AC panel. You should never have current flowing over the grounding electrode conductor unless a fault is occurring, so this must be avoided. And more importantly, if the main AC power panel ever experiences and outage or the breaker trips, the bond is restored. Without that bond, you have no protection from AC faults to the vehicle chassis if you're in the current path.

Schneider provides wiring diagrams, so I've attached the one that is closest to my setup. The big difference is that I had to make my own DC switchgear since theirs was too limited and some ground routes are changed for a van/chassis environment. They also don't picture the L1 and L2 hot busbars in the AC switchgear, nor the added breakers and the contactor. I renamed the system control panel on the top right as (gateway), since I have that device instead. It lets me program, monitor, and control the inverter/charger (Conext SW 4048, more on that later) from my phone or laptop.

That's all for now. Lots more in the works.

Cheers.
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Discussion Starter · #135 · (Edited)
I've come to realize this build thread is a useful journal. I can't tell you how many times I've looked through past posts to remind myself of some exact value I've already figured out, like a fuse size or bolt/nut size. I may be writing mostly to myself here, but it's still coming in handy.

Today I'm posting the re-worked front power panel, and some test results from using a $50 16-Ton hydraulic lug crimper, plus comparing a few different brands of lugs (takeaway: 16mm2 is NOT for 6 AWG, and Selterm lugs have some issues).

FRONT POWER PANEL:
I re-worked the front power panel that mounts in the sidewall behind the driver's seat. Two important things happen here: 1) 48V power is converted down to 13.8V for house loads, and 2) the van's dual AGMs and alternator provide a backup supply in-case the lithium bank or the DC converter is down for any reason (high/low temps, system maintenance or upgrades). I'm fairly certain I'll use that backup ability, even though it required some extra cost and effort.

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Beginning on the bottom right, a Blue Sea / Bussman 90A breaker will be fed directly from the vehicle's dual AGM positive terminal via 4 AWG Ancor marine 105C fine stranded tinned copper wire. I had to use the pricier breaker with both outputs on the bottom due to space limitations. I may add a 250A MIDI fuse (or mini-ANL) in one of the open spots in the fuse box under the driver's seat to offer some additional protection for the line feeding this breaker, but based on all accounts, accessing the CCP and other fuses down there is a PITA, so I only want to go in once. A short circuit may well blow even a 250A fuse before a 90A breaker trips.

Bottom-middle is the red 1-2-OFF Blue Sea selector switch (mounting screws are purposely loose for now; #10-32 x 3" into t-nuts on the back). The switch is upside down because that worked for my wiring needs. The output terminal (5/16) of the 90A breaker will feed (4 AWG) the input terminal (3/8) Position 1 on the switch, which is accessible from the bottom.

Directly above the 1-2-OFF switch is a Blue Sea ANL fuse holder. It's 5/16 output will feed (4 AWG very short) the input terminal (3/8) Position 2 on the switch, which can be accessed from the top.

Top left is the large Daygreen 48V > 13.8V 80A DC-DC converter. It's positive #10 output on the bottom right will feed (4 AWG) the ANL fuse switch's 5/16 input. I chose an ANL fuse instead of a breaker because generally speaking DC to DC converters can't be pushed beyond their max without serious risk of equipment damage. If my house loads ever demand around 80A, either in normal conditions or due to a short, I want that fuse to blow quickly (I may use a 70A or 80A, still deciding). It's easier to quantify the house load amps than the converter input amps because input voltage and the ambient temperature both affect converter efficiency. The converter will also have a breaker on its (6 AWG) input side (not pictured) closer to the 48V house batteries, which doubles as a switch, and I can adjust the breaker size if I find this isn't working as planned.

So far my experience with Daygreen products has been good. The only thing you have to be aware of is that venturing up into the 70A territory briefly is okay, but for the most part you have to de-rate these (and most other electronic components) by as much as 30% in the summer. Fortunately my DC house loads will max out at 50-60A (if that) in the summer, and will only be higher on the coldest days of the winter when all of my heat pads (tank and battery) and heat traces (plumbing) will be on. Those are the best times to push electronic equipment, including DC converters, since heat dissipation is at its very best. Even so, I'll probably avoid going beyond 70A. I've also convinced Daygreen to create a 150A 13.8V version, and by next winter I may have upgraded to that.

For now you can only find higher amperage DC converters at 12V flat, but that's too low for optimal device efficiency. My heating pads for instance all operate at max efficiency at 13.5V, which is right around the voltage they'll see after accounting for wire distance and the higher amps that'll be present when all heating devices are running.

The last two devices on the panel are a Blue Sea fuse block (middle right) which will supply a few nearby LED lights and a 100W 12/24V PD charger (top right; using a temp mounting system because I may relocate). I have two other Blue Sea fuse blocks like this in the van, one on the passenger side behind the slider door (power runs under floor) and one driver's side near the rear wheel well. They each have 6 AWG wire and are fed by the output of the Blue Sea 1-2-OFF switch (left side, also accessible from bottom).

HYDRAULIC CRIMP TOOL AND LUG COMPARISON:
I decided to try a 16-Ton hydraulic lug crimper from Amazon. It's only $50, so why not, and Amazon is great about returning (which I did). The good news is that this crimper works great on 2/0 lugs of any kind. The bad news is it's worthless on 6 AWG lugs, which many of these hydraulic crimpers claim you can do with their 16mm2 die. This is also influenced by the barrel thickness of the lug you're working with and the wire thickness, but the long-and-short is 16mm2 dies ARE NOT compatible with 6 AWG if you want a welded crimp. Other hydraulic lug crimpers state 4 AWG or at-best 5 AWG are the highest (smallest wire size) you can go with 16mm2 dies. That sounds correct based upon my tests. Just because you can't tug the wire out doesn't mean the crimp is adequate. See for yourself:

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Aside from my shoddy hack-saw job (blade's label rubbed off, hence the yellow splotches), and the fact that I used some scrap 6 AWG wire that had fairly large strand-size for this test, you can still clearly see there is no weld on this crimp. Strands are spaced with plenty of air between them. And that's with thick AIRIC 6 AWG lugs (really like that brand, good quality, good price, very long barrel which is ideal anytime space isn't limited; wish they made larger sizes and short barrel versions for tight spots).

I won't even bother to picture this same test with 6 AWG 5/16 Selterm lugs (Amazon) because they won't crimp at all with a 16mm2 die. Even with the crimp dies beyond touching, and doing it multiple times, you can pull the lug right off. Part of that is because 16mm2 definitely isn't the ideal size for 6 AWG, but part of that is the lug. At least with the thicker AIRIC lugs you can't pull the wire out.

Now onto the good news. The hydraulic crimper did a much better job with 2/0 lugs and the 70mm2 die. For this test I was willing to waste a little of my good Ancor marine 2/0 fine stranded wire since these connections in my build are mission critical. I had a few extra 90 degree lugs I bought from the Crimp Supply Store (Amazon reseller) that are considered "power lugs" or "heavy duty starter lugs" type sourced from AC Terminals. I compared a crimp using one of those with a 2/0 Selterm (Amazon) lug. First, the Selterm:

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As you can see, the portion of the wire remaining in the lug (top right) looks like a good weld. However, the flared sleeve (top left) literally fell off as I finished sawing, and the top portion of wire is clearly not welded.

Next the Crimp Supply Store's AC Terminals heavy duty starter 2/0 lug:
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Now that's a good looking weld. There is a small pocket near the middle on the lug (top left), but overall this is acceptable.

It turns out Selterm and Ancor Marine are selling a type called "starter lugs", whereas FTZ Industries and AC Terminals make thicker "power lugs", sometimes also called "heavy duty starter" lugs, so it's not really a fair comparison between these two categories. But this does give you an example of a starter versus power lug; note the thinner bottom layer of this Selterm 2/0:
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And the AC Terminals "power lug" 2/0:
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And while Ancor Marine lugs (top) are "starter lugs" and also have a thin bottom layer, they do have a longer barrel, which makes for a better crimp. Here's a head-to-head comparison. I had cut the Selterm open, so it was a tad longer originally, but not much:
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Based on these tests, I sent the Selterm lugs back and ordered Ancor Marine lugs instead. I probably should have gone with the super thick FTZ Industries (seamless design, the best) power lugs or AC Terminals heavy duty starter lugs for everything, but I decided my current-carrying needs are rarely if-ever going to top 150 amps (48V), and for that a regular starter lug is already sufficient. You also have to use larger dies or be cognizant not to over-crimp power lugs.

However, I did find one rare occasion where the Selterm lug was a better: the DC converter's narrow output terminals required a smaller 4 AWG Selterm lug to fit.

I also returned the 16-Ton hydraulic crimper and bought a 12-Ton hydraulic crimper that has a smaller 10mm2 die. This has worked out perfectly, because now I can crimp 6 AWG at 16mm2 to get the wire firmly in-place (using quality thick lugs), then come back and put a tighter crimp with the 10mm2 die. I just don't crimp all the way down with the 10mm2, or it will make the crimp wall too thin.

The 12-Ton also works well on the large 2/0 70mm2 crimps, and it appears to be more manageable for those times where I need to crimp something that's inside the van.

I know you can have lugs crimped at local auto stores, but seriously, that's not gonna work for me based on the sheer volume of lugs I have to crimp and the evolving needs of my power system. Plus, you have to trust the person behind the counter knows what they're doing and is paying close attention. Maybe they have a 16mm2 die and think it's fine for 6 AWG?

Cheers.
 

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Discussion Starter · #137 ·
Have we found a way to utilize the ForScan to keep the Ford AT&T wifi on longer...or without having the key in ignition?
I haven't even tried. Most OEM devices like that don't offer enough customization for my needs, so I'm using this router that uses less than 5W and this DC converter to power it. I haven't gotten that far but there's a way to have it use your phone's internet. See amazon reviews.

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Discussion Starter · #138 · (Edited)
Since I had to go back and update the crimp post above, here's an update for anyone who may have read the first post before I updated it. That thick lug I tested from Crimp Supply Store (Amazon reseller) appears to have been a "heavy duty" starter lug sourced from AC Terminals. FTZ Industries is another well-known company (the guys at Marine How-To approve) that makes extreme "power lugs," and theirs are also seamless, not sandwiched like most lugs, possibly making them the very best lug for situations that can handle the size and weight.

I decided that since my power needs will rarely if-ever cross 150A (at 48V), I didn't need the extra thick power lugs for everything. I'm happy to have them for those few 90 degree situations, but the longer-barrel Ancor Marine starter lugs are now my default.

Also, don't even bother with Wirefly lug kit on Amazon. They claim the barrel is extra thick, but nope. This set is going back. Here's their 4 AWG lugs (top) versus the AIRIC lugs I like (bottom):
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Cheers.
 

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Discussion Starter · #139 · (Edited)
In preparation for the battery and inverter installation, it was time to devise and install an emergency venting system that would bring fresh air into the battery and inverter compartment if my air conditioner failed for any reason.

I like hot places, and a vehicle parked in the sun in AZ in the summer on a 120F day can result in 140-170F temps inside. That's unacceptable with a massive 20kWh lithium bank, even if the inverter, charge controller, and alternator regulator all have temp sensors to stop charging beyond about 110F. Just having lithium batteries at 140-170F -- even the safest LFP type -- is dangerous, and at very least it will drastically shortening their lives.

Limiting the upper temp range to ambient 120F max (the hottest I've ever seen it) is a big step in the right direction, so having a programmable system to automatically bring fresh air in when van temps cross 110F was an important goal.

This provided both a challenge and an opportunity. In the hot months I don't want or need venting (aside from the emergency system described above) because with refrigerated air you specifically don't want outside air being exchanged with your costly cool a/c output. And in the cold months, I don't want or need venting because the same logic applies to my webasto heat output. But in those middle months when the sun can warm the van up to just a bit above what's comfortable, and instead of wasting power on a/c I could just vent in some cool air, then a general-purpose venting system would be useful. But it's still an afterthought with 24/7 climate control capability being the main solution (and expense), and I'm mostly doing this for the emergency scenario, so there were some compromises.

By not putting a fan in the roof, I get more space for solar, which can help run the a/c during the hot months with fewer alternator recharging cycles. That's a big win, so roof fans were out for me. So that meant inline fans, and I needed temp-controlled emergency activation, so AC Infinity's Cloudline fans were perfect for this. They let me program in an "alarm" temp at which the fans will go into max speed. I currently have it set to 110F, which should indicate a problem has occurred with my air conditioner, and it's time to use venting as a backup to keep the van at ambient. I may adjust that lower, and it's secondary to the normal temp-sensing speeds, so if I set the normal speeds to 80F and level 3, the fans still come on at a low speed, but only go into alar mode and speed 10 if temps keep climbing.

A 6" fan can still move more air at a lower speed (quieter) and overall move more air at max speed even if it's reduced to 4" at the input. Reducing does cut down on flow, but I may find my a/c is rock-solid reliable and end up using the 6" to just circulate cool refrigerated air from down near the floor into the battery and inverter compartment, in which case a 6" fan would be better since it can run at a lower/quieter speed. For those reasons I went with a Cloudline T6, and an S6, which is controlled by the T6.

The T6 fit perfectly under my Dometic fridge platform and on top of the OEM rear a/c. I'm glad I got rear a/c, since it's not in the way for my build, and it keeps the back cool on long road trips in the summer and let's me arrive at my destination already chilled. I was experiment with black and white ducting, but ended up going with black. I just haven't swapped this side out yet. The front 6" duct that will feed the battery compartment isn't installed yet in this photo.

I have 4" duct heading into both d-pillars where the rear LED light switch normally is (driver's side) or just a blank plastic cover (passenger side). I moved the LED switch to another spot (easy), tidied up the brake light wiring inside the pillars and widened the little side tabs to make more space, and then ran the duct down through the pillar bellow the van to those OEM removable rubber rectangular inserts. Someone on the forum gave me the idea, but I can't remember their username.
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Passenger side fan sits directly above the webasto, and so far isn't in the way at all.
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At first I had the diver's side pulling fresh air in, and the passenger side pushing hot air out. But running venting up to the roof to suck hot air out sounded like an eyesore, so I tested with both fans bringing fresh air in, and I found it was not only more effective at bringing the van to ambient, but the passenger-side fan provided a nice cool stream of air all the way up to the front swivel seat where I normally hang out. Cracking the windows was the key, since that let hot air escape and increased the airflow past the swivel seat.

I have a pair of slider vents on the way so I can leave those in the windows when parked for long periods. But I don't want to mess with installing and removing them all the time, so I'm probably going to add passive vent holes (with sealable dampers) to the top of the passenger rear door so that hot air is forced out at that height. I may also add some on the sides of the van near the top.

The fans are quiet overall, especially at low speeds, but not as quiet as a typical roof fan with very large blades and no ducting. That's to be expected with any kind of inline fan, but most of the time the a/c will be doing the work and the fans will be off, so it's a good compromise.

Because Cloudline fans (at least the newer ones) are all AC powered, there's no way take advantage of their controller (timers, temp sensor, etc) if you try to modify them to run on DC power. I tried, and believe me I got deep into the fan and it's componentry, but decided it's not worth it. They draw so little power even losing 8% on conversion is fine.

I already had a small $40 300W pure sine giandel inverter for the winter months for watching TV with the main inverter off (it's quieter that way). My TV only consume 38W, and the inverter's tiny fan doesn't even turn on unless you get up to about 100W, so adding another 11W per fan on speed level 3 made no difference (and that's measured on on the 12V DC input side so it includes all losses). And the only time I'll use the fans and this little inverter is when the main a/c is off, so I'll have boatloads of extra power.

Even when/if the fans go into the alarm mode (temp above 110F), they still consume only 65W each, so 130W total -- but they move a LOT of air, which is the goal for that emergency situation. My battery bank is 20kWh, and the alarm mode can only happen if the a/c has failed for some reason and temps are rising, so at that point I should have plenty of power. Even if I decide to run the little inverter off the van's dual AGMs in-case the lithium bank goes offline for some reason, 130W is about what the dometic uses, and I was able to go a few days with it running before the AGM's needed recharging. I'm also planning to explore a system to auto-start the van idling to recharge the AGMs and the house bank, so that problem may not exist at all someday.

The S6 fan has a long cord for being controlled by the T6, but I extended it with two 72" molex extension cables, and ran that plus an extension cord in split-conduit up into the passenger side d-pillar over the top and down through the driver's side d-pillar. That way both fans are powered by one inverter, and I even made it so I can just plug them into a nearby power strip that runs off the main house bank if I decide that system is very reliable.

I need to mount the controller and get a photo of it, but in the meantime, here's Cloudline's photo that shows the idea:
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All that's left is cleaning up the duct intakes below the van. Right now I just have the vent exiting the rectangular hole where the rubber insert covers usually are. I put some screening on the duct ends to keep bugs out, but I hope to 3d-print or otherwise build a clean solution. I tried adding hepa filters and other kinds of in-line vent filters but they block too much airflow.

It's looking like a little gravity damper installed with the flaps facing up (so gravity pulls them back down when not in use) may be the way to go. It blocks airflow too, although not as much, so I'm not yet decided. The other option is speedi-boot makes a 6" damper that I can put on the fan's 6" outlet inside the van and close the vents from inside. Both of those options are nearly fully sealed dampers whereas the average damper you'll find online are just that --dampers -- not terminators. You'd think they'd make dampers close all the way, but it's apparently not that common, and terminators aren't adjustable, they just stop flow completely. I still feel like there's a better solution, and I just haven't gotten that far yet.

So many projects so little time!

Cheers.
 

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Wonderful to read. So little info out there about roofless ventilation!

Those fans are sick. DC ones would seem ideal, but those humidity and temp features are cool, the manufacturer seems legit and somehow this all more reliable than jamming together the same get-up using computer fans.... which is what people usually suggest... which seems like a total faff.

Now I wanna do the same! In my case, roofless ventilation is primarily due to stealth concerns (midwest, urban, daytime company parking lot — fans would be primarily for my dog in case the AC ever quit in the summer).

Can't wait to read more about:

— how you finish off the D pillar vents. People talk about using these all the time on these forums but I swear so few seem to have actually gone through with it!

— what vent holes w/ dampers ya ultimately go with. Agree the window ones seem cumbersome. So interested where/how ya do the passive venting up towards the front.
 
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