Charging 2 seperate house battery banks from alterntor?

Dynamystic

New member
Hey there,

This is my first post to these forums and I'm sure if this is the best location for the post but here it goes.

I have an e350 6.0 powerstroke that I have converted to a full time living camper van. I also tow a cargo trailer to haul my work tools and gear. In the front of the trailer I have built a larger kitchen for the added comfort.

I have the van set up with a couple 80ah agm batteries with a keyline isolator. It has also been upgraded to the 180A DC Power alternator. So far this set up has been working well but I'm considering upgrading the van to a 100ah lithium setup with b2b charger and a couple solar panels. I'd then move the current van setup to the trailer for some much needed 12v power.

My question is can I set this new system up where I can safely (for the alternator mostly) charge both the van house batteries AND the trailer house batteries AT THE SAME TIME from the alternator while on the road?

I'd share my thoughts but I'd rather just hear how you'd do it rather than have my ideas torn to shreds as they probably deserve.

Thank you much,
Josh

Sent from my SM-G970U using Tapatalk
 

high-and-dry

New member
Yes you should be able to. As a rule lead acid batteries charge at 10% and agm are lead acid but they can go a little higher. If the batteries are flat they may take more like 50% but that wont be for long as they take a charge. So even 2 80 amp hour batteries if they are way down will only draw 80 amps for a little while.

Now the lithium will be able to take a faster charge, but the chance that all batteries are very low is slim, but your alt is big enough to handle it for while until the agms slow there acceptance rate.

Ideally I would find a battery combiner that limits the output out to the second battery. I cant remember than name but there is one that only allow like 10 amps to go to the second battery. It is commonly used in boats to keep a starter battery and house battery charged but completely separate. It is basically a battery charger that runs on another battery not a plug in
 

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dreadlocks

Well-known member
thats incorrect, most lithium batteries will gladly try to smoke your alternator and themselves in the process.. however many amps they capable of outputting they are capable of absorbing, its a good idea to have something limiting current to 0.4C or whatever your manufacturer stipulates.

Check out Victron's Smart Orion DC Chargers, they will limit the current and can be programmed for long lithium lifes.. you might need another one for the trailer to boost voltage and wattage because otherwise charging a battery through a OEM trailer plug is rather pointless.
 

Verkstad

Raggarkung
Sure you can.
Probably the safest method is two B2Bs with adjustable current limiting for house and camper respectively.
Unless its some kind of ’drop in’, Lithium will need it because they can draw much higher current that whats good for them and your alternator.
For your lead batteries, You might get by without B2B. But due to the likely ’long distance’ charging circuit involved. Its probably best to use B2B on that circuit too.
 

john61ct

Adventurer
This is totally straightforward, you just need to get up to speed over time if you want an optimal setup, at lowest cost per year.

First off, you should only have one House bank unless circumstances truly do not allow that.

Second, prepare for your next bank when the time comes, to be composed of top notch proper deep cycling units, together with proper care they will last much longer than what you're starting with.

When charging over long distances are involved, you need either very heavy / thick gauge wiring, or put in place a DC-DC charger to avoid excessive voltage drop.

Download BSS Circuit Wizard and get familiar with the variables involved.

Running low-amp loads does not require as thick wire, and a bit of V drop is NBD.
 

Dynamystic

New member
Thank you all for the speedy replies.

Ideally I would find a battery combiner that limits the output out to the second battery. I cant remember than name but there is one that only allow like 10 amps to go to the second battery. It is commonly used in boats to keep a starter battery and house battery charged but completely separate. It is basically a battery charger that runs on another battery not a plug in
Check out Victron's Smart Orion DC Chargers, they will limit the current and can be programmed for long lithium lifes.. you might need another one for the trailer to boost voltage and wattage because otherwise charging a battery through a OEM trailer plug is rather pointless.
Sure you can.
Probably the safest method is two B2Bs with adjustable current limiting for house and camper respectively.
Unless its some kind of ’drop in’, Lithium will need it because they can draw much higher current that whats good for them and your alternator.
For your lead batteries, You might get by without B2B. But due to the likely ’long distance’ charging circuit involved. Its probably best to use B2B on that circuit too.
This is totally straightforward, you just need to get up to speed over time if you want an optimal setup, at lowest cost per year.

First off, you should only have one House bank unless circumstances truly do not allow that.

Second, prepare for your next bank when the time comes, to be composed of top notch proper deep cycling units, together with proper care they will last much longer than what you're starting with.

When charging over long distances are involved, you need either very heavy / thick gauge wiring, or put in place a DC-DC charger to avoid excessive voltage drop.

Download BSS Circuit Wizard and get familiar with the variables involved.

Running low-amp loads does not require as thick wire, and a bit of V drop is NBD.
Thankfully, it seems like I'm on the right track but with some refinement for sure. Here is where I'm at with the plan.

I plan to run a wire from my starter battery to a 4-way switch, but wired to the switch in reverse of the design (which apparently is ok). The starter battery will be connected to the output of the switch. Then, instead of the switch functioning to toggle between battery banks to draw from, it will be choosing which of the 2 house banks to feed from the alternator, with the additional option of charging both, or neither. I can certainly keep an eye on the banks and switch manually between them if needed but that seems tedious. The question is whether switching to feed both at the same time can be done in a way that is safe for both alternator and each of the 3 battery banks. From what I'm hearing, it sounds reasonable if careful consideration is taken to wiring capacity, and voltage regulation, especially with the lithium ion addition to the mix. Wiring wise, I think I'll just invest, play it safe, and connect all 3 banks to the switch with 1/0AWG 100% copper which should help with drop issues on the way back to the trailer batteries (which I intend to mount in the front of the trailer). I don't run heavy loads but I don't like narrow margins either. I've heard good things about Anderson Connectors for the trailer connection.

It seems that when investing in lithium batteries (or any batteries for that matter), it is well worth the cost to also invest in a proper dc-dc charger. I was considering the Sterling Pro 30A but have recently been toying with the idea of the Renogy DCC50S to simplify installation and save space. I'm generally skeptical of all-in-ones but this has been getting some good reviews as far as I've seen, especially with vanlifers with limited space. Now, if they just had an AC-DC-MPPT all-in-one, life would just be so much simpler. I will also check out the Victron a little closer since I've been considering their MPPT if the all-in-one turn too good to be true. Overall, it is clear that some form of DC-DC charger (probably on both banks) is a good idea to regulate voltage from the alternator. The question would then be finding the right combination of voltage regulation between the van house and the trailer house so as not to stress the alternator. This I am still not perfectly clear on. Perhaps I'm just a little paranoid but the Renogy at 50A seems a bit much for this setup unless I was to dial down the trailer bank like High-and-dry mentioned. Am I right to think that 2 Renogy might not be the best option if both were drawing full capacity from my alternator? If i understand things right my alternator puts out just under 100A at idle. I will be looking into lower amp DC-DC options for the trailer bank just to be informed of my options. Suggestions? It really would be nice to have the MPPT and DC-DC in one though with the possibility to easily expand the trailer setup with a couple solar panels as well down the road. I already have the Keyline Isolator from the agm setup. I was considering keeping it for the trailer bank but now am having second thoughts. It seems more prudent in this case to use 2 dc-dc chargers, but if someone manages to give me the confidence, I'd consider keeping it in the interim to save a few bucks. It just doesn't save anything if I damage batteries or tax my pricey alternator. Thoughts? Am I missing anything in my thinking?

I also should mention that when I'm parked for long periods of time, like on a job-site, I tend to plug in both the van and the trailer. In the van, with my current 2 80AH AGM, i run an 8A Battery Minder AC charger to keep things topped off. Although I hope to rely primarily on the 200W solar and alternator in the van, I plan to keep the AC charger with the AGM's when I move them to the trailer since it is more often stationary, plugged in, and won't have solar (for a while anyways). I was thinking of replacing it in the van with the NOCO Genius10 for the new lithium battery. It is my understanding that it can't hurt to maintain when plugged in and the isolator aspect of the DC-DC charger prevents any complications with that AC Charger and the starter batteries. I would love to know if this is a correct understanding. I've been using the AC charger with the keyline isolator with no apparent issues but just want to make sure there isn't anything subtle I might be overlooking.

I really appreciate your feedback as I sort through all this.

Josh
 

Dynamystic

New member
My lady just took this one where we're currently residing with family on the western slope of CO while we make our upgrades.


Sent from my SM-G970U using Tapatalk
 

dreadlocks

Well-known member
You do have one of the rare exceptions where two house banks does make sense, most people try to use em like dual fuel tanks and it dont make sense for battery storage.

the all in one units also fail all as one, and cant expand/grow.. Victron's more modular approach would be more suitable for such a rube goldberg setup as you've got here IMO.
 

Dynamystic

New member
You do have one of the rare exceptions where two house banks does make sense, most people try to use em like dual fuel tanks and it dont make sense for battery storage.

the all in one units also fail all as one, and cant expand/grow.. Victron's more modular approach would be more suitable for such a rube goldberg setup as you've got here IMO.
Yeah, I think two house banks will serve my needs well and I do plan to keep them independent aside from the possibility of charging from the same source (alternator). You are right when you say "all in one units also fail as one". Hence my reservations. I'm looking into Victron options but so far have not seen a lot of readily available information, specs, etc. I'll keep digging.

I had to look up Rube Goldberg. Haha, his cartoons feel a little too appropriate for how I've pieced my setup together over time.
 

dreadlocks

Well-known member
Victron's got some of best documentation out there, its all on their website with detailed spec sheets.. and you can even install the app on your phone and play with virtual units to see what configuration options they got.
 

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Dynamystic

New member
Victron's got some of best documentation out there, its all on their website with detailed spec sheets.. and you can even install the app on your phone and play with virtual units to see what configuration options they got.
You are right about the documentation (maybe too much). Didn't realize initially that I had to find the specs as pdf through the download tab.
Thanks
 
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