An Unusual RV System Configuration Question

[Dontatsu]

So I hope this is interesting enough to get the attention of the "Pros". I currently have an RV set up with rooftop solar and a Victron Inverter/Solar Charge Controller and Controls. I have 4 x 100ah Battleborn batteries. I have come into possession of a couple Epoch 460ah batteries. Normally my 400ah system is fine for my short term boondocking needs but I attend Burning Man every year and I am in a desert environment for about 10 days at a stretch.

My solar isn't enough to keep up with the loads, especially the Air Conditioning so I supplement with recharging using my onboard Onan diesel generator or a Westinghouse dual fuel running propane. The generators are, however, a bit noisy and have exhaust issues (especially the Onan). I would like to extend my running time by, for the 10 day period, paralleling the Epoch(s) into my system using a pre-wired Anderson connector.

What are the potential issues with this kind of temporary setup? I know that I will be mixing battery types and capacities. How serious an issue is that for the short term? Also what are the issues with connecting the batteries when they are in different states of charge?

What other issues am I missing that I need to account for?

Any and all advice is welcome.

 

[sunshine_eggo]

Capacity and count disparity means you're unlikely to get even charge/discharge from the batteries, so they will all vary in their state of charge.

However, you'll still effectively have the full 1320Ah capacity, it just may be a little sketchy trying to get all of it out at high current while at low SoC.

Ensure batteries are within 0.2V of each other before connecting.

 

[Dontatsu]

Capacity and count disparity means you're unlikely to get even charge/discharge from the batteries, so they will all vary in their state of charge.

However, you'll still effectively have the full 1320Ah capacity, it just may be a little sketchy trying to get all of it out at high current while at low SoC.

Ensure batteries are within 0.2V of each other before connecting.

I think I can minimize the difference by fully charging the Epochs before I leave and making sure my onboard battery bank is at 100% on arrival and hooking them up immediately upon arrival.

 

[Rocketman]

Also, consider adding a Gen-turi.

https://a.co/d/aV6SZtv

I added it to my diesel Onan - it puts the fumes and some of the sound up above the RV roof.

You can hang out near the exhaust and not get fumed out.

 

[Watts Happening]

I don’t foresee it being an issue. Very worst case scenario they’re way out of balance, think BB at 10% and epoch at 90%, you may trip the bms of the epoch as the BB try to suck up too much current.

Again, simply keep them close to same state of charge and you should be good.

Wave as you drive through Reno on your way to that hell forsaken place LOL

 

[Dontatsu]

Also, consider adding a Gen-turi.

https://a.co/d/aV6SZtv

I added it to my diesel Onan - it puts the fumes and some of the sound up above the RV roof.

You can hang out near the exhaust and not get fumed out.

I had one but it was stolen unfortunately. I'll have to pick up a replacement.

 

[wme]

2 SCC and a manual battery transfer switch

 

[Watts Happening]

Second idea, why not swap for the epoch batteries to be the main/day to day batteries, sell the battle borns and buy one more epoch if needed?

 

[Dontatsu]

Second idea, why not swap for the epoch batteries to be the main/day to day batteries, sell the battle borns and buy one more epoch if needed?

I considered that but I think the Epoch are just too big to fit into any of my bays.

 

[Watts Happening]

I considered that but I think the Epoch are just too big to fit into any of my bays.

Gotcha, worth measuring for sure. Remember that there are false walls in RV’s. I hid (2) victron multiplus inverters, a charge controller and (12) battle borns behind a false wall in our RV years ago.

 

[time2roll]

Are not both batteries basically LFP? With this premise I see no issue in mixing them in parallel for a 10 day excursion.

Connect them from the start at full voltage and let them run.

With all that battery it may reduce generator time if there is increased charging capacity to really load the generator to 80% not to exceed the battery charge limit.

 

[Kiwi2000]

It will be fine. A battery bank with 4 100Ah batteries and 2 460Ah batteries in parallel will perform better than a battery bank with 4 100Ah batteries in parallel. Every battery will contribute to load and absorb charge.

What you could do is connect the 4 100Ah batteries in parallel amongst themselves and call it a 400Ah battery. Then connect that with the other 2 460s to a bus bar arrangement. Then the loads will practically see 3 big 400ah batteries.