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
