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designing battery for my travel trialer

frthompson

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May 29, 2021
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I am in the planning stages for building a battery to replace the the 300 ah lithium battery in my travel trailer with something about twice that big. I'm considering using 270-320 3.2v cells arranged in two 4S batteries with their own BMS put in parrallel. I was planning on using two of the JBD/Overkill solar 12 V 4S 120 a bms. I know the alternative is to go 24 v with an 8S bms but I think I want to stay at 12 V because thats what my trailer is. Need to be able to draw up to 200-240 amps at 12 V. So does that design sound like the right option? I am curently following discussions on the forum about sourcing the cells. I have a Victron solar charger and Multipluss 3000 inverter charger in my trailer. Thanks--Frank
 
The only thing I grok that might affect this, is if you are using 2 120 A BMS in parallel, but you are saying that you plan on drawing 240A from the bank, that is not leaving you any head room on the BMS. I would be a little concerned that you might go into an over discharge situation easily.
 
The only thing I grok that might affect this, is if you are using 2 120 A BMS in parallel, but you are saying that you plan on drawing 240A from the bank, that is not leaving you any head room on the BMS. I would be a little concerned that you might go into an over discharge situation easily.
if it is short burst it should be fine... my 120a single BMS starts my onan .. which is 170a inrush
 
Yes I was concenred about designing in some extra capacity in the BMS but when I said I need 200-240a that was rounding up a bit and would not be often. Also not aware of a good alternative bms to step up to?
 
Also not aware of a good alternative bms to step up to?
I am in the exact same situation with my RV. Currently 4 GC2s and moving to lithium. Really want to use 4x 280 - 320Ah cells, a good BMS, and call it a day. A lot of RVers have a ~2kw inverter. That size seems to be super popular since it supports microwave ovens, etc. Would be great to have a simple, reliable, inexpensive BMS that would support that. An Overkill/JBD that supported > 200A would sell well.
 
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