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I've settled on a DC-AC-DC electrical system design I am happy with. Some of it blatantly stolen from @gregoryx and others (thanks!)

I would appreciate comments, questions, and criticism.

I have a 2020 with dual alternators/batteries, so lots of spare amps available. The roof rack will be used for toys - kayaks, skis, rooftop tent, etc, so not much room for solar. Also, I don't tend to sit still for long - I'm always driving somewhere to hike or bike. Therefore, this system is solar light and alternator charging heavy.

I am posting two images. The first is the DC-AC-DC system, the one I am asking to be reviewed.

The second is basically identical, but it swaps out the DC-AC-DC system for an equivalent B2B system (in terms of charging amps). The second is more informational, for those who are interested in learning more, not for review.

Thanks!!

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Only thing I'd really change is 24V instead of 12V. When we're talking 3kW+ inverter and 1.5kW+ charger, it's big amperage at 12V. Price is the same to do 24V for all the Victron gear; just need a 24V>12V to convert back. Change the two SOKs to series instead of parallel. And then you've got room to add more batteries since you're not sitting at 400A already - you're at half that. Basically, just cuts all the amps in half and allows smaller wire and easier future growth potential for storage.
 

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1. Do you really need 3KW inverter? Have you added up your expected loads?

2. Read the 2200 watt inverter install instructions. My 1000 watt vehicle powered inverter required a 150 amp class T fuse. You have a 150 amp fuse for a 2200 watt inverter. Suspect 2200 watt inverter could draw more than 150 amps.

3. 40 amp CB on solar is useless. Check amperage output of the two 75 watt panels. I have read that a CB is not functional on solar positive. I have a 15 amp CB between my 300 watt high voltage panel and the solar controller. May not be functional but is useful to turn off the solar input to the controller to eliminate power to the 12 volt system.

5. I have a CB on AC between the inverter and the 120 volt AC duplex outlet. Also first outlet should be GFCI.

6. I do not have the large combination AC/DC fuse block. DC has a CB between the DC bus bar and the Blue Sea fuse block. AC has a CB between the house inverter and the first AC duplex outlet. Battery positive has a fuse and disconnect switch between the battery and the input to the house inverter.

The link to my electrical diagram:

68b108_dc953400e3a74b568b7d32938ca1fc7e.pdf (filesusr.com)
 

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My plan and equipment choices are quite similar. I have never built anything electrical like this and @gregoryx has been incredibly generous with advice. Here are some questions (more so than suggestions/advice given my lack of experience).
  • I see you have your negative for the Giandel wired to the bus bar. Not sure how long that run is in your layout. If they are far apart and the Giandel is directly behind the drivers seat, you might want to consider connecting that negative to a nearby vehicle ground (D-ring, vehicle battery after it's BMS or "official ground between the seats)
  • I wonder if the battery protect device is necessary. The BMS in the SOK has a low voltage disconnect (10.4V) in it's BMS. Do you want the disconnect at a higher voltage for some reason or just some redundant protection? FYI - I don't see the full set of BMS values on the SOK web page but have attached a document (from a reseller?) below. Come to think of it, even though I have no reason to doubt this info I did not confirm win Min at SOK (note: to self)
  • I will have a DC fuse block on each side of the van so that I will only need to run one wire across the van and more importantly to make it easier to add circuits at a later date.
  • I'm curios why chose the Victron fused distribution device and a shut off for your DC fuse block vs a conventional bus bar and resettable breakers. I have not made a decision on this yet.
  • I am thinking about wiring in GFCI outlet immediately after the Giandel. Mostly for the protection but it could be used to directly power an AC load if you want to do so without running the Mutliplus and batteries. This might be nice if using the van a back up generator for a house as @orton has suggested and done.
  • I don't see any details on your shore power input. Have you decided what type of breaker and if you will be going with 30A or 15A.
 

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And Holy crap, just buy a cheap 2kW inverter and do the "Orton method" rather than spending a grand or whatever on four of those sad little victron dc-dc chargers.
I have a single alternator and have made the decision to go with the @orton method, because even with the inefficiency vs B2B(s) I estimated that it would provide at least the same rate of charging and possibly more. Since the B2Bs always put out max amps the only way to vary the output is the brand and number of devices. With the 2 inverter approach the charge current on the Mutiplus can be "dialed" in. My hopefully conservative calculations are that 70A charge rate would be possible. In the case of the Victron B2Bs my estimate was that the van's alternator could support 2 x 30A, (@$250 eas) but 3 might be pushing it. Even if 3 was possible the additional 20A of charging capacity did not seem worth $450.
Also sinc my electrical will be in the passenger rear, the smaller AC wiring is also a benefit.

Based on @gregoryx's experience the 2.2KW inverter seem like a pretty good match with the output of the Ford. I suppose if one was trying to max out the vans capacity regularly a the slight incremental cost for a 3KW might be warranted.
 

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.Read the 2200 watt inverter install instructions. My 1000 watt vehicle powered inverter required a 150 amp class T fuse. You have a 150 amp fuse for a 2200 watt inverter. Suspect 2200 watt inverter could draw more than 150 amps.
The CCP2 connection that the 2.2KW inverter is connected to is fused under the drivers seat at 170A. Most folks are using the 150A breaker outside of the seat to provide a convenient shut off and to hopefully open before the inconvenient to change fuse fails. The only load on the 2.2KW inverter is 120A charger in the Victron Multiplus. Not sure of the charger efficiency, but if that results in a load of greater than 150A on the vehicle inverter, the Multiplus charge rate can be set lower. In my case with a single alternator, I will be using that feature to start with the charge rate dialed back to around 70A and will adjust accordingly once I get a handle on what the alternator temperatures are. This flexibility is one of the main reasons I chose to use the @orton method with the Victron house inverter vs B2B. IMO (see above post)
Both the AC and DC cables from the inverter are 4/0. AC has 1/10 the amperage compared to DC. I used a # 2 from a 1000 watt inverter for the DC to the DC bus bar and 14/3 for the AC.
I did a double take on that as well, but upon further review, the 4/0 the OP is showing is the DC negative back to the bus bar. AC wire size is not called out.
I have a CB on AC between the inverter and the 120 volt AC duplex outlet. Also first outlet should be GFCI.
Are you referring to your vehicle powered inverter? It looks like that CB and GFCI are protecting both your vehicle "shore power" and true shore power via your switching implementation. Is that correct? Also I see a GFCI on the AC output of your house inverter, but no breaker which seems to be common. Is that because the breaker on the infeed AC also covers the output or is there some fusing internal to the inverter? That one still confuses me.
 

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Are you referring to your vehicle powered inverter? It looks like that CB and GFCI are protecting both your vehicle "shore power" and true shore power via your switching implementation. Is that correct? Also I see a GFCI on the AC output of your house inverter, but no breaker which seems to be common. Is that because the breaker on the infeed AC also covers the output or is there some fusing internal to the inverter? That one still confuses me.
The real shore power and the vehicle powered inverter output both go to a selector switch so I can select one or the other source. After the selector switch is a 15 amp two pole circuit breaker.

There is a two pole circuit breaker between the house inverter AC output and the first GFCI duplex outlet. As I recall the 1000 watt Magnum inverter/charger/transfer switch has an internal 20 amp CB. The inverter is buried inside a cabinet so added a second CB where it is accessible.
 

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Only thing I'd really change is 24V instead of 12V. When we're talking 3kW+ inverter and 1.5kW+ charger, it's big amperage at 12V.
Yes, I thought about this. From a pure cost perspective, they were about the same - the cables are bigger but are very short. The deciding factor was that I have room to expand to 3 but not 4 batteries, and I want to stick with 12V batteries.

And Holy crap, just buy a cheap 2kW inverter and do the "Orton method" rather than spending a grand or whatever on four of those sad little victron dc-dc chargers.
I'd like to suggest that you read my post again :) My design proposal IS for DC-AC-DC - the first image. The second image is informational. Not everyone understands the difference, so I thought that two images side by side would be helpful for those trying to wrap their head around this "debate".

1. Do you really need 3KW inverter? Have you added up your expected loads?
It is 3KVA, so 2400watts. Yes, I've done the needs assessment. It might be a bit bigger than I need, but Victron is good kit, the monitoring is the best, and the Victron community forum is super helpful. The Victron 2KVA would likely be too small, and it has a weird tall form factor that is harder to install.

2. Read the 2200 watt inverter install instructions. My 1000 watt vehicle powered inverter required a 150 amp class T fuse. You have a 150 amp fuse for a 2200 watt inverter. Suspect 2200 watt inverter could draw more than 150 amps.
For DC-AC-DC, this will be capped by the Victron shore power limiter. If I do use this 'initial' inverter directly (as you do for your heater), you are correct that I will have to be careful. This DC line as a 175A fuse under the seat, which is a pain to change, so the 150A breaker protects that deeply buried fuse.

3. 40 amp CB on solar is useless. Check amperage output of the two 75 watt panels. I have read that a CB is not functional on solar positive. I have a 15 amp CB between my 300 watt high voltage panel and the solar controller. May not be functional but is useful to turn off the solar input to the controller to eliminate power to the 12 volt system.
Thanks for that. I actually plan to start with zero solar, so I sort of threw that into the diagram at the last second for completeness. I will revisit.

4. Both the AC and DC cables from the inverter are 4/0. AC has 1/10 the amperage compared to DC. I used a # 2 from a 1000 watt inverter for the DC to the DC bus bar and 14/3 for the AC.
I did not specify the size of the (grey) AC cable. The 4/0 is only for connecting Multiplus to battery (through the busbar), and for the chassis ground. Probably marine 12/3 for the AC. Sorry for the confusion.

5. I have a CB on AC between the inverter and the 120 volt AC duplex outlet. Also first outlet should be GFCI.
Can you explain more about the reason for the CB? I am aware of GFCI, thanks.

  • I see you have your negative for the Giandel wired to the bus bar. Not sure how long that run is in your layout. If they are far apart and the Giandel is directly behind the drivers seat, you might want to consider connecting that negative to a nearby vehicle ground (D-ring, vehicle battery after it's BMS or "official ground between the seats)
Good eyes. I am half-converting a passenger van, so all electricals, including the Giandel, are in the back. In other words, I have a fat cable running from CCP2 through the walls to the electrical area. (I did not want to clutter up this diagram, but I also ran a medium cable from CCP1, along with spare light cabling for signaling or whatever.) Given that, grounding the Giandel to the bus bar makes sense. The bus bar will be very securely grounded to a D-ring.

  • I wonder if the battery protect device is necessary. The BMS in the SOK has a low voltage disconnect (10.4V) in it's BMS. Do you want the disconnect at a higher voltage for some reason or just some redundant protection? FYI - I don't see the full set of BMS values on the SOK web page but have attached a document (from a reseller?) below. Come to think of it, even though I have no reason to doubt this info I did not confirm win Min at SOK (note: to self)
That was a late add, and I plan to dig more into it. It was suggested by someone in a Facebook solar forum: "Depends on your BMS. Some disconnect if their calculated SOC is at 10%. I disconnect the loads when the BMV712 hits 20%. Some BMS devices on some batteries (Battleborn) will disconnect at 10%, as they should, but require a trickle charge to re-engage. Additionally, I don't want my battery's BMS to disconnect on low SOC since that would remove power from devices that i want alive during low SOC. As an example, the BMV shunt. Also, I have a Cerbo and want to keep it alive so i can interrogate it. However, I do have the batter protect set to eventually disconnect DC loads on under voltage, which would occur over a long period of time. I only have the BP on my DC loads.".

Anyone want to weigh in on this choice?

  • I will have a DC fuse block on each side of the van so that I will only need to run one wire across the van and more importantly to make it easier to add circuits at a later date.
Yes, I am doing the same.

  • I'm curios why chose the Victron fused distribution device and a shut off for your DC fuse block vs a conventional bus bar and resettable breakers. I have not made a decision on this yet.
Unless building your own, all the bus bar parts add up to pretty close to the price of the Lynx distributor. I like the clean install lines you can get with the Lynx. Having said that, when I go to lay it all out, if it turns out that physically splitting the positive and negative bus bars, for real estate purposes in a tight space, is a good idea, I will EBay the Lynx. I happened to have the shut off lying around - didn't give it much thought honestly. I do know I want to be able to de-power my primary cables.

  • I am thinking about wiring in GFCI outlet immediately after the Giandel. Mostly for the protection but it could be used to directly power an AC load if you want to do so without running the Mutliplus and batteries. This might be nice if using the van a back up generator for a house as @orton has suggested and done.
Good points. I don't know what I would do with it offhand, but might as well have that option. Thanks.

  • I don't see any details on your shore power input. Have you decided what type of breaker and if you will be going with 30A or 15A.
I haven't decided. I can't use the extra juice for charging, because my Multiplus is limited to 120A charge rate. I doubt I will ever need to use 30A AC directly. Still noodling on the 'periphery'.

@ChrisW8 Sorry to stomp on your thread, but I thought most of this would apply to your setup to since your plans are so similar to mine.
Stomp? Not at all. This is exactly the sort of discussion I was hoping for.

Thanks everyone!!
 

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FWIW, finally posted some stuff on my electrical build. Addresses methods for many of the things brought up above - GFCI, shore-power switching, etc. posted some stuff on my electrical build

Can't argue with the 12V SOK thing. I recall checking a while ago and they didn't offer a 24V.

Personal take is 200A is pretty big and is at the point where it should be cut down to 100A; but technically no difference. That 12/24 thing was a factor in which batteries and panels I chose - after dealing with 3 x 255Ah @12V AGMs, I was eager to get the amperage down. 12V with that amperage is /really/ picky about super solid connectors and all that - which are tougher to get right with the larger cable. As I remind myself, there's a reason that house electrical is 120V or more - and transmission lines are MUCH more. Higher voltage is better (if slightly more dangerous). But if I couldn't have sourced 24V batteries, I'd have made the same adjustments.
 

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I haven't decided. I can't use the extra juice for charging, because my Multiplus is limited to 120A charge rate. I doubt I will ever need to use 30A AC directly. Still noodling on the 'periphery'.
IIRC when plugged into shore power, the Victron has the ability to pass through any current in addition to the AC loads to use for charging. I was figuring that with water heating and induction cooking being my large AC loads, the with 15A not having much power to pass through for charging during the short duration of those loads would not a big deal since shore power would most likely be an overnight thing so the batteries would get fully charged anyway (and I've got 3 of those 205A suckers). But, if an AC was added into the mix at sometime, the 30A shore connection might then be helpful. I'm trying to build in future proofing for that scenario as well as the possibility of going down the off grid A/C rabbit hole should that be necessary to retain my navigator. But sans any possibility of adding A/C, I can't see much benefit to a 30A shore inlet.
 

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FWIW, finally posted some stuff on my electrical build. Addresses methods for many of the things brought up above - GFCI, shore-power switching, etc. posted some stuff on my electrical build

Can't argue with the 12V SOK thing. I recall checking a while ago and they didn't offer a 24V.

Personal take is 200A is pretty big and is at the point where it should be cut down to 100A; but technically no difference. That 12/24 thing was a factor in which batteries and panels I chose - after dealing with 3 x 255Ah @12V AGMs, I was eager to get the amperage down. 12V with that amperage is /really/ picky about super solid connectors and all that - which are tougher to get right with the larger cable. As I remind myself, there's a reason that house electrical is 120V or more - and transmission lines are MUCH more. Higher voltage is better (if slightly more dangerous). But if I couldn't have sourced 24V batteries, I'd have made the same adjustments.
I am vacillating on this one. Having bought 3 batteries, which is probably overkill right now, I am now at 12V. I went that way because (I think) they can squeeze in my layout so why not make it so running out is less of a concern, I am at 12V. But I'd like to leave open the possibility to expand reasonably easy to accommodate of grid A/C should that be necessary to keep my navigator engaged in this endeavor. So I am now in the position of adding yet more excess to current capacity to avoid the possibility of needing to replace the expensive Multiplus. I've got some more thinkin' to do on this one yet. Hey at least I've decided on DC-AC-DC.

So what does this have to do with @ChrisW8's set up. If he puts his batteries in series to go to 24V and wants to expand in the future, he is tied into adding a pair of batteries, but if he stays at 12V, then he can add one at a time.
The wiring size is only an issue if the reason for expanding is higher loads in addition to greater storage capacity.

Another theoretical advantage of 24V is that with the 24V-12V DC converter the voltage to the supply for 12V loads can be well regulated. Don't know how much of a real world benefit there is of this with the very flat discharge curve the LiFPO has.
 

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I'd like to suggest that you read my post again :) My design proposal IS for DC-AC-DC - the first image. The second image is informational. Not everyone understands the difference, so I thought that two images side by side would be helpful for those trying to wrap their head around this "debate".
LOL, sorry, couldn't resist some friday night clowning - I tend to go straight to the pretty pictures and don't always read carefully if it's been a long day. 🤣


FWIW, finally posted some stuff on my electrical build. Addresses methods for many of the things brought up above - GFCI, shore-power switching, etc. posted some stuff on my electrical build
Maybe I should ask this in your build thread, but I too am curious how your 150A breaker has held up to the loads your Giandel 2.2kW truck inverter is drawing, specifically did you have to dial down the charging output of your Victron Multiplus or is the 150A working okay? Seems like I saw you post somewhere a while back that it maxes out at about 1750W which puts you just shy of 150A at 12V or more like 125A if you divide by 14V... but I don't remember the specifics.
 

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IIRC when plugged into shore power, the Victron has the ability to pass through any current in addition to the AC loads to use for charging. I was figuring that with water heating and induction cooking being my large AC loads, the with 15A not having much power to pass through for charging during the short duration of those loads would not a big deal since shore power would most likely be an overnight thing so the batteries would get fully charged anyway (and I've got 3 of those 205A suckers). But, if an AC was added into the mix at sometime, the 30A shore connection might then be helpful. I'm trying to build in future proofing for that scenario as well as the possibility of going down the off grid A/C rabbit hole should that be necessary to retain my navigator. But sans any possibility of adding A/C, I can't see much benefit to a 30A shore inlet.
Accurate on the pass-through thing. And they act as a pretty strong "uninterruptible power supply" as well - quick switch-over and all that.

And I'm not even sure the 30A shore power would be useful then; I'm unclear how it might handle /more/ than its rated power - it is rated to go all the way to 5kW but not as the continuous output - where does pass-through fit in that?

But the max charging is less than 2kW, so while 30A might be good for the over-all rig setup, it wouldn't do any more charging than a 15A service.


I am vacillating on this one. Having bought 3 batteries, which is probably overkill right now, I am now at 12V. I went that way because (I think) they can squeeze in my layout so why not make it so running out is less of a concern, I am at 12V. But I'd like to leave open the possibility to expand reasonably easy to accommodate of grid A/C should that be necessary to keep my navigator engaged in this endeavor. So I am now in the position of adding yet more excess to current capacity to avoid the possibility of needing to replace the expensive Multiplus. I've got some more thinkin' to do on this one yet. Hey at least I've decided on DC-AC-DC.

So what does this have to do with @ChrisW8's set up. If he puts his batteries in series to go to 24V and wants to expand in the future, he is tied into adding a pair of batteries, but if he stays at 12V, then he can add one at a time.
The wiring size is only an issue if the reason for expanding is higher loads in addition to greater storage capacity.

Another theoretical advantage of 24V is that with the 24V-12V DC converter the voltage to the supply for 12V loads can be well regulated. Don't know how much of a real world benefit there is of this with the very flat discharge curve the LiFPO has.
Agreed on the whole challenge. The real advantage to the DC-DC converter is that you'll actually deliver 12-12.5V - not 14.5+ which has caused issue with the MaxxAir in the past and may with other things. But it's a tough call. I'd say add a battery in your case if you have room and go series for @ChrisW8 if possible. I think we get stuck on the 12V thing being ideal and we're not adapting to the rather massive amount of power we're storing in these relatively small-and-light batteries. 12V is not ideal for stuff this size. 48V might actually be better; but 24V is a readily available compromise.

LOL, sorry, couldn't resist some friday night clowning - I tend to go straight to the pretty pictures and don't always read carefully if it's been a long day. 🤣
Right?!?! :LOL:


Maybe I should ask this in your build thread, but I too am curious how your 150A breaker has held up to the loads your Giandel 2.2kW truck inverter is drawing, specifically did you have to dial down the charging output of your Victron Multiplus or is the 150A working okay? Seems like I saw you post somewhere a while back that it maxes out at about 1750W which puts you just shy of 150A at 12V or more like 125A if you divide by 14V... but I don't remember the specifics.
Yeah, the dial-down thing is the key. As @njvagabond has articulated in another post recently, this model relies on change the load / draw to affect how much draw the truck-inverter pulls. This is pretty different than the Orton model; his model is keep the inverter down-sized enough that it's not a big load. This model has the advantage of the inverter running at a fraction of its rated capacity; which means lower heat, less noise, and possibly (if the Victron charts are similar to the Giandel) more efficient generation. (There's room to argue that the efficiency is there when the highest rating with the lowest temp - indicated by fan speed - is present.)

So... yeah, the Multiplus is easily adjustable from a Cerbo / Venus setup - by mobile device or by the touchscreen. To be clear, it is NOT easily adjustable from the Multiplus - that is actually /terrible/ and requires a PC with a USB connection. But Victron Venus software can be loaded on a Raspberry Pi - talk about cheap and easy - so there's really NO reason not to have a Venus / Cerbo in any Victron system at this point.

As to the max-out... I've pushed the draw side all the way to over 2kW. The charger side of the Multiplus 24/3000/70 is 70A @ 24VDC - which is going to be @ 29.2VDC when pulling hard, so technically right at 2kW. That was with an 18A @ 120VAC limiter. I didn't leave it there long because 2kW @ 12V is right at 170A (on the truck side of the alternator / input). It did not pop the 150A circuit breaker (not a hard rush thing, I'd guess) but I didn't want to pop the 175A fuse, so I dialed it back. But it does work...
 

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(There's room to argue that the efficiency is there when the highest rating with the lowest temp - indicated by fan speed - is present.)
Is efficiency important with either a B2B or vehicle powered inverter system? The question is how much more money in fuel is spent each year. Not a significant cost even if the alternator is outputting for a longer period of time due to lower efficiency.
 

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so there's really NO reason not to have a Venus / Cerbo in any Victron system at this point.
$$$ - isn't the communication interface + the fancy display about $750 vs < $150 for the Multiplus Control panel.
Yes you get a lot of whiz bang stuff, but if someone is just interested in easily changing input current then ...
Even the Multiplus control seem a bit steep for just that one function. I do like the idea of that "assistant" function you previously pointed out as a possible solution to change between two input current limit settings at the flip of a switch (for a cost of a few bucks) Factory Dual Alternator System and LiFePo4 battery pack .
 

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Is efficiency important with either a B2B or vehicle powered inverter system? The question is how much more money in fuel is spent each year. Not a significant cost even if the alternator is outputting for a longer period of time due to lower efficiency.
The most significant factor in my case is the agility to safely maximize the charging rate from the alternator. Since there are no B2B's with an adjustable output current limit and the various models come in fairly large output increments (if one was to use multiple units) my estimate was that even with the lower efficiency of the DC-AC-DC approach, the ability to dial in the charge rate on the fancy Victron inverter will most likely result in an equal or greater charge rate than that of the B2B approach. Should I find the possible charge rate significantly higher than my estimate, then multiple B2B's may have been able to provide a greater rate than the DC-AC-DC approach. But in that case, the charge rate would be so high relative to my requirements that the incremental improvement would not have much real word benefit. However that B2B approach would cost be more costly and complicated because multiple devices and a long run of heavy cabling required. I agree that any impact on fuel consumption is not material. So in my case DC-AC-DC seems to make sense. It took me a long time to get there, but I have learned a lot along the way (or so I think).
 

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The most significant factor in my case is the agility to safely maximize the charging rate from the alternator. Since there are no B2B's with an adjustable output current limit and the various models come in fairly large output increments (if one was to use multiple units) my estimate was that even with the lower efficiency of the DC-AC-DC approach, the ability to dial in the charge rate on the fancy Victron inverter will most likely result in an equal or greater charge rate than that of the B2B approach. Should I find the possible charge rate significantly higher than my estimate, then multiple B2B's may have been able to provide a greater rate than the DC-AC-DC approach. But in that case, the charge rate would be so high relative to my requirements that the incremental improvement would not have much real word benefit. However that B2B approach would cost be more costly and complicated because multiple devices and a long run of heavy cabling required. I agree that any impact on fuel consumption is not material. So in my case DC-AC-DC seems to make sense. It took me a long time to get there, but I have learned a lot along the way (or so I think).
Wednesday I used the vehicle powered inverter and drove for 45 minutes. House AGM battery SOC went from 93% to 94%. Was thinking there was an issue until I realized the charger was probably in absorb mode so alternator charging was not very useful with a high SOC AGM battery. Alternator charging should be more useful with a lithium that does not restrict the amperage at high SOC. Solar is more important with an AGM to slowly get back to 100% SOC. The reason the battery had a lower SOC was because I was running our house refrigerator and freezer using the van during a 8 hour power outage. Also ran a cord from van for the roofing contractor for his tools who was replacing my barn roof.

Fortunately I almost never need to use alternator charging. My electrical usage is low enough and in my climate the 300 watts of solar just does its thing.

I read where lithium should not be fully charged to extend the battery life. How is that prevented if you are charging from the vehicle powered inverter?

The major advantage for the DC-AC-DC system for my use is the availability of AC power with the engine running. I use it more for heating shower water or heating air than it is used for charging.

I think I was the first person to use a vehicle powered inverter instead of directly connecting to the vehicle 12 volt system with a relay. That was 10 years ago and I have used that system in two conversions. Was interesting to get so many comments about how stupid it was and everyone just connects the two batteries together for charging. Everyone was very concerned about how it was less efficient. Now with lithium batteries it seems to make even more sense.
 

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I read where lithium should not be fully charged to extend the battery life. How is that prevented if you are charging from the vehicle powered inverter?
This could be accomplished by using a programmable charger that has a "constant current" "constant voltage" setting. In CC/CV mode set the voltage to that which represents the state of charge you desire, and set the current to a limit that is safe for the battery that is being charged.
 
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