[totalgeek]

Hi all, I've got a 2020 Transit with the dual AGM battery and dual alternator option. I plan to install a lifepo4 battery bank of somewhere around 400-600ah (undecided on 12v or 24v still) and I'm trying to figure out how to set up my electrical system to maximize the charge going into my house battery bank. I've seen this topic discussed a lot here on the forums and was originally gonna piggyback onto some older threads, but then thought it might make more sense to create a new thread so as to not hijack others threads.

For reference, I've read the following threads on this subject thru a couple of times over

800AH LiFePo4 - 2x250Amp Alternators - How to maximize?
Charging Large (800 amp hour) House Battery Bank from Alternator??
2020 Transit -- Alternator Charging the House Batteries
Fast charging advice needed: dual alternators, 2020 Transit all electric LiFePO4 campervan

Here are my basic electrical needs

Energy Needs
I've calculated that I need roughly around 5000 watt-hours of energy per day, with a peak of around 2500-3000 watts max surge load if I avoid running multiple high watt devices at the same time (cooking mostly)

Charging
I want all of the following...
(Solar) Rooftop mounted solar panels - depending on the system config I could possibly at most get 600-900 watts of solar
(Shore) Connect to standard 15amp household service (maybe 30 amp RV style, but not sure)
(Vehicle/Alternator) Would like to be able to charge my house batteries via alternator when driving at the maximum amperage for the alternators and electrical system (175-200 amps peak?) that the Ford system allows for with safety headroom.

Based on reading all of the threads listed above I see that this has been talked about a lot on this forum and that many members have 2020s with large battery banks and they're trying to accomplish the same thing. It seems to me that there are two possible paths to take...

1) Use CCP2 and connect a DC-DC charger (or multiple DC-DC chargers in parallel) pulling up to about 160 amps from the vehicle battery system and sending that over to the house battery system with the correct lifepo4 charge profile.

2) Use the DC-AC-DC method with multiple inverters, where one inverter is connected to CCP2 and acts as the current limiting device, which then sends power to the second inverter or shore charger that can then charge the battery. (I might not be understanding this correctly so please correct me if I'm wrong)

Are there other options that I'm missing here? I've been stuck for a couple of weeks now trying to figure out what path to take here.

Another compounding factor with my system design is trying to figure out which direction to go with the pack voltage. Was originally going with 12V, but so many have suggested going with 24v based on having a roughly 3000 watt inverter needed for loads that I would be better served, safer, and cheaper to go with 24v. That all sounds good, but it causes headaches in terms of charging via the alternators since I'm having to deal with going from 12v (vehicle) to 24v (house) which means I'm losing amps making the jump up to 24V in the DC-DC scenario (unless I'm missing something)

Would love to hear from those that have experience here for any insight they can offer? @orton @Vanpackr @keitho @DanD @harryn @huj @epiphVANy

Thank you!

 

[natecostello]

To achieve your desired alternator based charge rates (which I'm not sure the factory alternators/cabling will support for extended periods of time), I'd go with the "Orton method" for alternator charging (DC->AC->DC). That would free you up to evaluate a 24V house system. I'm not aware of B2B systems that can do high power 12V->24V conversion.

If I were doing a clean sheet 24V system, I'd go with the single factory alternator (and leave that to vehicle systems) and install a dedicated 24V Wakespeed controlled second alternator from Nations for the house system.

 

[orton]

2) Use the DC-AC-DC method with multiple inverters, where one inverter is connected to CCP2 and acts as the current limiting device, which then sends power to the second inverter or shore charger that can then charge the battery. (I might not be understanding this correctly so please correct me if I'm wrong)

You understand this method correctly.

The vehicle powered inverter powering the shore power charger can provide a proper 3 stage charging profile that matches the battery construction.

The advantage of using a vehicle powered inverter instead of a B2B is the availability of 120 volt AC power for other uses besides charging.

Link to my electrical design:

Electrical | Orton Travel Transit

www.ortontransit.info

At the bottom of the page is the printable PDF of the electrical diagram. Be happy to answer any questions. The web site includes a email form.

 

[keitho]

I'd agree with Orton; I went with just DC-AC-DC charging from my starter batteries to house, and skipped the DC-DC charger you mentioned from the CCP. If you decide to attach 2 different high loads to the starter batteries (the DC-DC, as well as an inverter), you'll need some control circuitry on both of them to ensure you don't overload the alternators/batteries. They also will both need to respond to the "load shed" signal from the vehicle, and be locked out if the alternators aren't running. That's the main reason I just did a single high-amp load--easier to do the control circuits for just 1 device.

I like what @natecostello suggested, and I really like 24V systems now that I've done more reading and research. I have 12V, and that has its advantages; but, I might consider something like what he mentioned if I ever build a brand new van again.

For shore power connection, unless you've got a really long cable run inside the van, I'd go with a 30A plug, breaker, and wiring. If you're putting in a big battery bank that can handle fast and high-current charging without breaking a sweat (sounds like you will be far under 1C even with a 30A AC charger), you might be happy for it some day when you pull into an RV site and need some quick juice before taking off again. Lots of home and apartment garages have 30A and even 50A service, now that people are charging EV's there, so you might have a chance and need to use it someday at someone's home, apartment, workplace, etc. The up-side when you're using 15A or even a 1000W portable generator--the heavier gage wire in your van will more efficiently pass along power (less resistance)

On the topic of shore, I ended up following the marine code, and put a 30A main breaker as the first stop after the shore power plug. It is a line/neutral breaker (not just line), so that, when I turn it off, there is no chance of that circuit being energized, even if I've mis-wired something downstream. From my shore plug to my breaker, and then on to my main charger, I hacked up a 50A extension cord that was marketed for use on welders, found it pretty cheap--I used it mostly because it was cheaper and easier than buying other types of heavy-gage wires.

Just don't do what I did, and thoughtlessly use a 30A RV plug to normal 120V outlet adapter, without sizing the extension cord properly. I was lucky, and noticed the cheap extension cord heating up (before it did anything except get way hotter than I was comfortable with)--it wan't really the best tool for trying to pull a full 15A from shore for a full charge cycle!

 

[Jay Dawes]

Hi all, I've got a 2020 Transit with the dual AGM battery and dual alternator option. I plan to install a lifepo4 battery bank of somewhere around 400-600ah (undecided on 12v or 24v still) and I'm trying to figure out how to set up my electrical system to maximize the charge going into my house battery bank. I've seen this topic discussed a lot here on the forums and was originally gonna piggyback onto some older threads, but then thought it might make more sense to create a new thread so as to not hijack others threads.

For reference, I've read the following threads on this subject thru a couple of times over

800AH LiFePo4 - 2x250Amp Alternators - How to maximize?
Charging Large (800 amp hour) House Battery Bank from Alternator??
2020 Transit -- Alternator Charging the House Batteries
Fast charging advice needed: dual alternators, 2020 Transit all electric LiFePO4 campervan

Here are my basic electrical needs

Energy Needs
I've calculated that I need roughly around 5000 watt-hours of energy per day, with a peak of around 2500-3000 watts max surge load if I avoid running multiple high watt devices at the same time (cooking mostly)

Charging
I want all of the following...
(Solar) Rooftop mounted solar panels - depending on the system config I could possibly at most get 600-900 watts of solar
(Shore) Connect to standard 15amp household service (maybe 30 amp RV style, but not sure)
(Vehicle/Alternator) Would like to be able to charge my house batteries via alternator when driving at the maximum amperage for the alternators and electrical system (175-200 amps peak?) that the Ford system allows for with safety headroom.

Based on reading all of the threads listed above I see that this has been talked about a lot on this forum and that many members have 2020s with large battery banks and they're trying to accomplish the same thing. It seems to me that there are two possible paths to take...

1) Use CCP2 and connect a DC-DC charger (or multiple DC-DC chargers in parallel) pulling up to about 160 amps from the vehicle battery system and sending that over to the house battery system with the correct lifepo4 charge profile.

2) Use the DC-AC-DC method with multiple inverters, where one inverter is connected to CCP2 and acts as the current limiting device, which then sends power to the second inverter or shore charger that can then charge the battery. (I might not be understanding this correctly so please correct me if I'm wrong)

Are there other options that I'm missing here? I've been stuck for a couple of weeks now trying to figure out what path to take here.

Another compounding factor with my system design is trying to figure out which direction to go with the pack voltage. Was originally going with 12V, but so many have suggested going with 24v based on having a roughly 3000 watt inverter needed for loads that I would be better served, safer, and cheaper to go with 24v. That all sounds good, but it causes headaches in terms of charging via the alternators since I'm having to deal with going from 12v (vehicle) to 24v (house) which means I'm losing amps making the jump up to 24V in the DC-DC scenario (unless I'm missing something)

Would love to hear from those that have experience here for any insight they can offer? @orton @Vanpackr @keitho @DanD @harryn @huj @epiphVANy

Thank you!

Hi

Hi all, I've got a 2020 Transit with the dual AGM battery and dual alternator option. I plan to install a lifepo4 battery bank of somewhere around 400-600ah (undecided on 12v or 24v still) and I'm trying to figure out how to set up my electrical system to maximize the charge going into my house battery bank. I've seen this topic discussed a lot here on the forums and was originally gonna piggyback onto some older threads, but then thought it might make more sense to create a new thread so as to not hijack others threads.

For reference, I've read the following threads on this subject thru a couple of times over

800AH LiFePo4 - 2x250Amp Alternators - How to maximize?
Charging Large (800 amp hour) House Battery Bank from Alternator??
2020 Transit -- Alternator Charging the House Batteries
Fast charging advice needed: dual alternators, 2020 Transit all electric LiFePO4 campervan

Here are my basic electrical needs

Energy Needs
I've calculated that I need roughly around 5000 watt-hours of energy per day, with a peak of around 2500-3000 watts max surge load if I avoid running multiple high watt devices at the same time (cooking mostly)

Charging
I want all of the following...
(Solar) Rooftop mounted solar panels - depending on the system config I could possibly at most get 600-900 watts of solar
(Shore) Connect to standard 15amp household service (maybe 30 amp RV style, but not sure)
(Vehicle/Alternator) Would like to be able to charge my house batteries via alternator when driving at the maximum amperage for the alternators and electrical system (175-200 amps peak?) that the Ford system allows for with safety headroom.

Based on reading all of the threads listed above I see that this has been talked about a lot on this forum and that many members have 2020s with large battery banks and they're trying to accomplish the same thing. It seems to me that there are two possible paths to take...

1) Use CCP2 and connect a DC-DC charger (or multiple DC-DC chargers in parallel) pulling up to about 160 amps from the vehicle battery system and sending that over to the house battery system with the correct lifepo4 charge profile.

2) Use the DC-AC-DC method with multiple inverters, where one inverter is connected to CCP2 and acts as the current limiting device, which then sends power to the second inverter or shore charger that can then charge the battery. (I might not be understanding this correctly so please correct me if I'm wrong)

Are there other options that I'm missing here? I've been stuck for a couple of weeks now trying to figure out what path to take here.

Another compounding factor with my system design is trying to figure out which direction to go with the pack voltage. Was originally going with 12V, but so many have suggested going with 24v based on having a roughly 3000 watt inverter needed for loads that I would be better served, safer, and cheaper to go with 24v. That all sounds good, but it causes headaches in terms of charging via the alternators since I'm having to deal with going from 12v (vehicle) to 24v (house) which means I'm losing amps making the jump up to 24V in the DC-DC scenario (unless I'm missing something)

Would love to hear from those that have experience here for any insight they can offer? @orton @Vanpackr @keitho @DanD @harryn @huj @epiphVANy

Thank you!

Hi, I want to know the exact same things. I’ve found lots of info from Orton and ask you if you can keep me updated as you learn more. Good luck on your build and Happy Trails !
Best, Jay Dawes

 

[guf]

Well I have a 48 volt system, kinda the same as a 24, that I'm trying to get it all figured out. Other that getting it to work I don't know what the heck I'm doing. I have a 48 volt inverter for my AC, I have a DC to DC charger thats connected to my CCP to charge my 4 battleborn wired in series. I have step down converter that goes to 12 volt and feeds a fuse box.

Honestly, reading and researching about it makes me wish I had a simple 12 volt system like everyone else. But its what I've got.

 

[totalgeek]

To achieve your desired alternator based charge rates (which I'm not sure the factory alternators/cabling will support for extended periods of time), I'd go with the "Orton method" for alternator charging (DC->AC->DC). That would free you up to evaluate a 24V house system. I'm not aware of B2B systems that can do high power 12V->24V conversion.

If I were doing a clean sheet 24V system, I'd go with the single factory alternator (and leave that to vehicle systems) and install a dedicated 24V Wakespeed controlled second alternator from Nations for the house system.

Thank you! I still think the 24v system has a lot of pros in its favor, it's just like you mention that there really are not any high power 12V -> 24V B2B options out there really. The only way to make it work is to buy multiple B2B chargers and put them in parallel, which adds cost and complexity. In hindsight I guess I should have worked through the alternator options better to figure out what could be done adding an external alternator outside of the Ford system, but the van I'm getting was pre-optioned with the dual alternators so it kind of wasn't much of a choice.

You understand this method correctly.

The vehicle powered inverter powering the shore power charger can provide a proper 3 stage charging profile that matches the battery construction.

The advantage of using a vehicle powered inverter instead of a B2B is the availability of 120 volt AC power for other uses besides charging.

Link to my electrical design:

Electrical | Orton Travel Transit

www.ortontransit.info

At the bottom of the page is the printable PDF of the electrical diagram. Be happy to answer any questions. The web site includes a email form.

Thanks orton! I'm going to dig into the wiring diagram more and see if I can get closer to conceptual system for my van. I'll probably be back with more questions or will reach out to you directly if there is something in your diagram or system I'm struggling to figure out.

I'd agree with Orton; I went with just DC-AC-DC charging from my starter batteries to house, and skipped the DC-DC charger you mentioned from the CCP. If you decide to attach 2 different high loads to the starter batteries (the DC-DC, as well as an inverter), you'll need some control circuitry on both of them to ensure you don't overload the alternators/batteries. They also will both need to respond to the "load shed" signal from the vehicle, and be locked out if the alternators aren't running. That's the main reason I just did a single high-amp load--easier to do the control circuits for just 1 device.

I like what @natecostello suggested, and I really like 24V systems now that I've done more reading and research. I have 12V, and that has its advantages; but, I might consider something like what he mentioned if I ever build a brand new van again.

For shore power connection, unless you've got a really long cable run inside the van, I'd go with a 30A plug, breaker, and wiring. If you're putting in a big battery bank that can handle fast and high-current charging without breaking a sweat (sounds like you will be far under 1C even with a 30A AC charger), you might be happy for it some day when you pull into an RV site and need some quick juice before taking off again. Lots of home and apartment garages have 30A and even 50A service, now that people are charging EV's there, so you might have a chance and need to use it someday at someone's home, apartment, workplace, etc. The up-side when you're using 15A or even a 1000W portable generator--the heavier gage wire in your van will more efficiently pass along power (less resistance)

On the topic of shore, I ended up following the marine code, and put a 30A main breaker as the first stop after the shore power plug. It is a line/neutral breaker (not just line), so that, when I turn it off, there is no chance of that circuit being energized, even if I've mis-wired something downstream. From my shore plug to my breaker, and then on to my main charger, I hacked up a 50A extension cord that was marketed for use on welders, found it pretty cheap--I used it mostly because it was cheaper and easier than buying other types of heavy-gage wires.

Just don't do what I did, and thoughtlessly use a 30A RV plug to normal 120V outlet adapter, without sizing the extension cord properly. I was lucky, and noticed the cheap extension cord heating up (before it did anything except get way hotter than I was comfortable with)--it wan't really the best tool for trying to pull a full 15A from shore for a full charge cycle!

Thanks for all of these tips and info keitho! I think I'm gonna stick with just one high amp load with the inverter connected to the starter batteries, that way it simplifies things for that connection point and having the system play nicely with the Ford system. It's kind of ironic that I never really paid much attention to the alternators on Ford Ecoboost engines before. I worked as an engine designer/engine builder for a racing company/Ford engineering firm and I dealt with Ford Ecoboost engines (3.5L/2.3L) everyday for almost a decade, and I never once ever paid attention to the alternator setups!

I'm gonna do some more thinking on this and I'll be back with more questions most likely!

 

[kenryan]

Please explain this fascination with 24 volt systems. Aside from being able to use marginally smaller wire sizes, what are the advantages?

 

[totalgeek]

Please explain this fascination with 24 volt systems. Aside from being able to use marginally smaller wire sizes, what are the advantages?

I'm not the most qualified to answer this (as I'm still learning) but I'll do my best to share what I've gathered so far in regards to the 12V vs. 24V question...

Reasons to use 24V instead of 12V

1) If you're planning to need more than 1000w (1500w) from your inverter it makes sense to step up to 24V due the reduction in amps on a 24V system
2) As you mentioned, being able to use smaller cable sizes is an advantage and cabling losses being lower in 24V versus 12V
3) Similarly to the above using 24V instead of 12V means all the components in the system (cables, lugs, fuses, breakers, busbars, etc.) can be smaller due to less amperage
4) 24V can save money on a solar charge controller since you get a lot more solar controller from 24V than you do from 12V, so you can get away with a smaller solar charge controller

Given my need for an inverter around 2500-3000 watts to handle my continuous and surge loads, it seems like 24V is the suggested best path to go with to keep the amperage within reason for the system as a whole. But again, I'm not an expert here and still learning as a I go, so if anyone has other input on this subject I'd love to here it. It seems like from reading other threads that @harryn has more expertise in this 12V vs. 24V comparison and when it makes sense to step up to 24V.

 

[RVing]

The advantage of a 24V system (alternator, house bank, inverter) is the ability to use smaller wires and interconnecting components. Smaller means a little cheaper and marginally easier to work with. The notion that there is less parasitic loss in a 24v system compared to a 12v system is true only if you don't size your wires correctly.

The disadvantage of a 24 vs 12v system is that most things provide or consume 12v, not 24v. Sure, you can buy and install a 24v (or 48v for that matter) alternator. And you can wire your batts as a 24v (or 48v) array. But stock vehicle alternators (and the most common aftermarket alts) are 12v. And we all have 12v loads of some kind to operate. And our wire runs are fairly short keeping wire costs down even if it means doubling the cross section area of the cabling used.

Now if you have a system where you need to buy everything from scratch (including the alternator), and have no real need for 12v, and especially if you have long wire runs, then 24 (or better, 48v) is the way to go. But that is not the situation most of us have in a van. That is the situation in say a fixed solar power system being installed in your house from scratch; thus these are designed around higher than 12v. But that is not our situation.

 

[totalgeek]

The advantage of a 24V system (alternator, house bank, inverter) is the ability to use smaller wires and interconnecting components. Smaller means a little cheaper and marginally easier to work with. The notion that there is less parasitic loss in a 24v system compared to a 12v system is true only if you don't size your wires correctly.

The disadvantage of a 24 vs 12v system is that most things provide or consume 12v, not 24v. Sure, you can buy and install a 24v (or 48v for that matter) alternator. And you can wire your batts as a 24v (or 48v) array. But stock vehicle alternators (and the most common aftermarket alts) are 12v. And we all have 12v loads of some kind to operate. And our wire runs are fairly short keeping wire costs down even if it means doubling the cross section area of the cabling used.

Now if you have a system where you need to buy everything from scratch (including the alternator), and have no real need for 12v, and especially if you have long wire runs, then 24 (or better, 48v) is the way to go. But that is not the situation most of us have in a van. That is the situation in say a fixed solar power system being installed in your house from scratch; thus these are designed around higher than 12v. But that is not our situation.

Thanks for sharing that info, could you offer your thoughts or comments on the difference in 12V vs. 24V when it comes to higher power inverters? Based on my understanding (which could be wrong) if I have a higher wattage need, then 24V is more ideal than 12V due to the amperage. For example

If I have a 3000 watt inverter requirement for my loads, then that means...

3000 watt inverter at 12V = 300 amps
3000 watt inverter at 24V = 150 amps

I think the math there is imperfect as I'm not accounting for conversion losses, but it's roughly illustrative of the difference in this 12V vs. 24V comparison based on a 3000 watt inverter need. Based on this doesn't it seem like the 24V system is preferable? It keeps the amps in a more realistic ballpark in terms of fuses/breakers and would be safer? Please correct me if I'm thinking about this incorrectly as I really want to get it right before I start buying components

 

[RVing]

I'd agree with Orton; I went with just DC-AC-DC charging from my starter batteries to house, and skipped the DC-DC charger you mentioned from the CCP. If you decide to attach 2 different high loads to the starter batteries (the DC-DC, as well as an inverter), you'll need some control circuitry on both of them to ensure you don't overload the alternators/batteries. A simple batt switch with form-C break before make contacts can be used to ensure the alt is only connected to one load at a time.
They also will both need to respond to the "load shed" signal from the vehicle, and be locked out if the alternators aren't running. Well the inverter might need that or not, depending how it is wired, but the B-B does not since it load sheds itself automatically. That's the main reason I just did a single high-amp load--easier to do the control circuits for just 1 device.
.
.
.

The up-side when you're using 15A or even a 1000W portable generator--the heavier gage wire in your van will more efficiently pass along power (less resistance). Yes, of course, but only if you don't properly size your wires in the first place.
.
.
.

see in red above

 

[Vanpackr]

If I have a 3000 watt inverter requirement for my loads, then that means...

3000 watt inverter at 12V = 300 amps
3000 watt inverter at 24V = 150 amps

Where you save is in the wire gauge requirements sat between your charging source and your battery and from the battery to the inverter. Your 12v appliances/lights are generally going to be fine with 12awg to 10awg within the van.

 

[RVing]

Thanks for sharing that info, could you offer your thoughts or comments on the difference in 12V vs. 24V when it comes to higher power inverters? Based on my understanding (which could be wrong) if I have a higher wattage need, then 24V is more ideal than 12V due to the amperage. For example

If I have a 3000 watt inverter requirement for my loads, then that means...

3000 watt inverter at 12V = 300 amps
3000 watt inverter at 24V = 150 amps

I think the math there is imperfect as I'm not accounting for conversion losses, but it's roughly illustrative of the difference in this 12V vs. 24V comparison based on a 3000 watt inverter need. Based on this doesn't it seem like the 24V system is preferable? It keeps the amps in a more realistic ballpark in terms of fuses/breakers and would be safer? Please correct me if I'm thinking about this incorrectly as I really want to get it right before I start buying components

First, if you need 3kw steady-state, I'd ask what the heck are you doing in that van?!

Second, after you tell me its none of my beeswax, I'd say if you need 3kw, steady state, then your inverter will need to be bigger than 3kw and will depend on the kind of loads you expect to operate. And I'd also say you'll need one big motha of a house bank.

If you really will be pulling 3kw out of an inverter, steady state, I'd go as high as you can voltage-wise. Since you'll be buying a new alternator (or two), I'd go right to 48v and wire your batts accordingly. And add a dc-dc converter for your 12v loads. You'll still need to decide how to charge the house bank.

But seriously, I highly highly doubt there are many on here that have a need for over 2kw steady from an inverter. Or, if they initially thought they needed that much, after realizing what it would take to provide that capacity, the decided the rooftop AC and induction cooktop and girlfriend and wife's hairdryers did not need to be running all at the same time. Most on here are are prob 1kw or less. I have a 2.8kw inverter but only to have the surge capacity to start a roof top AC which runs at around 1.3kw.

 

[RVing]

And while I'm at it, I don't get the advantage of using the inverter to power a 120v charger to charge the house batts. Crappy pix below to illustrate the 2 main approaches (maybe I'm missing something?). I put the switches in the position they'd normally be in.

Basically, all I see is trading a 120v charger for a B-B charger and adding endless hours to the inverter to power the 120v charger. For large inverter-powered loads (eg, rooftop AC at the limit of the inverter or its input), you need to remember to disconnect the batt charger and of course turn off other non-essential 120v loads. The inverter is powered by either the alternator or the house batts (though you could add a switch to feed the house batt to the inverter input but that'd require remembering to turn off that switch when charging).

In approach 2, you need to switch the inverter on (connect to batts or alterntor) to power 120v loads. If you power the inverter with the house batt and the engine is running, you get power form both the alt and the house batt (can't do that in approach 1 w/o additional switching and wiring). You can power the inverter directly from the alt (just like approach 1) but in this case you don't need to remember to turn off the batt charger.

In summary, the advantage of approach 2:
-can power inverter from house batt and alternator at same time
-lots less less hours on the inverter
-only one switch to operate in the typical use case of powering the inverter via the house batt while parked.
-don't need to remember to turn off the batt charger (or disconnect) when running large 120v loads at the limit of the inverter (or whatever is powering it) OR when powering inverter from house batt.

advantage of approach 1:
-depending if you want to disconnect the 120v charger or not, might be 1 less switch needed.
-120v batt charger prob costs less than a b-b

My thoughts anyway.

Edit: in approach 2 if the inverter switch has a "both" position (eg, bluesea 3002) you can jump start the van from the house bank.

 

[ranxerox]

Get a Magnum inverter, My 2,000 watter has a 800 watt surge capacity
There are a number of people on this forum who have gotten 3,000 watt magnum inverter's in the past.
Magnum sells 12, 24 and 48 volt inverter's.
In Residential solar power 12 volt inverter's are almost obsolete, Nobody uses them anymore except for small systems like in a Cabin. Everything else is 24 volts or higher.
I was reading about 1,500 volt solar panels the other day. (Commercial)
24 Volt alternators are easy to find, Both the military and construction equipment use them, Semi tractors too. along with 24 volt lighting and everything else.
Sterling sells 24 volt B2Bs and battery chargers, 36 volt and 48 volt ones too.

A listing of 24 volt refrigerators, Water pumps and you name it.

Search results for: '24 volt'

Backwoods Solar are experts in renewable energy & off-grid power solutions & systems. Since 1978 we've provided personalized solar, micro-hydro and wind power systems design and support.

www.backwoodssolar.com

 

[jondrums]

What about the Victron Buck-Boost converter? - I think it could charge your 24V bank from the vehicle's 12V alternator/battery. The 100A version is the highest power B2B I've seen.

Buck-Boost DC-DC Converter 25A / 50A / 100A - Victron Energy

Charge a 12/24V service battery in vehicles with an intelligent dynamo using the Buck-Boost DC-DC Converter. Find a dealer near you.

www.victronenergy.com

 

[natecostello]

@RVing, my use case for 24V is all about rapid charging and overall system optimization.

For example, with a 24V system, I can charge directly from a dedicated alternator with voltage and current control (via wakespeed) that is coordinated with the BMS (via can) at charge rates fully up to 0.5C on most lithium cells with a perfect profile with no problem. So for a 24V 400AH system, thats 200 amps which is totally doable with 2AWG or larger running from the engine to the house battery. And best of all I can do it without any intermediate power conversion.

I can charge off the engine for 30 minutes and put enough in the battery to run a mini-split AC off grid for several hours over night.

Doing the same thing with a 12V system would be very difficult.

As for other loads/sources, I can get the mini split, victron multiplus, isotherm fridge and freezer, and air compressor all in 24V varients. Also, my MPPT gets smaller for a given KW capacity. All the wiring servicing those loads/sources gets more than 2 sizes smaller. The only thing that needs 12V are max air fans, some LED lighting, comms equipment...small loads.

That is why I'm designing a 24V system...not so much base steady state load.

 

[orton]

Where you save is in the wire gauge requirements sat between your charging source and your battery and from the battery to the inverter. Your 12v appliances/lights are generally going to be fine with 12awg to 10awg within the van.

The only advantage I see for a 24 volt system is the lower cost of smaller diameter cables which is offset by the need to purchase a 24 volt to 12 volt DC converter.

In my conversion I have less than 5' of 12 volt cables for all the cables. 255 amp-hr AGM battery is located just in front of the driver side rear wheel, Magnum MSS1012 inverter charger/transfer switch is located above the driver side rear wheel and the positive and negative bus terminals, fuse and battery switch are located on a shelf above the battery.

All my house 12 volt cables with crimped fittings I had made by the Interstate battery store for $111.50. Suspect I could save maybe $10.00 on cable cost if I had a 24 volt system.

A 24 volt to 12 volt converter would cost about $100.

So for my conversion it would cost about $90.00 more to have a 24 volt system and require additional wiring for the converter and add one more item subject to failure.

House 12 V DC | Orton Travel Transit

www.ortontransit.info

Someone will point out I did not include the long 12 volt cable from the vehicle 12 volt system needed for charging from the vehicle. I do not have that cable. I have a 14/3 cord from the vehicle powered inverter that can power the Magnum charger. Same cord is used for the shore power connection.

So If you want to save money on 12 volt cables keep the components close to each other. I question the value of a 24 volt system in a small van that is not a mobile electrical sub station.

 

[orton]

my use case for 24V is all about rapid charging and overall system optimization.

How does 24 volt system charge faster than a 12 volt system? Why is overall system optimized because it is a 24 volt system?