Vigo
Solar Addict
I guess im not running my 12v system hard enough.. In my RV i have a '5kw' rated msw inverter and 3x lifepo4 batts totalling 360ah, and at this point i don't worry about the batteries themselves at all, just my wiring (which im constantly changing).
When I initially put that inverter in the RV it would not start the ~12k btu rooftop ac (i actually dont know the BTUs, it is 12-14k-ish) off the 2 lead acids in the RV because of drops in the cabling (one batt 3ft from inverter, other one 12ft, through existing 2ga cabling). As soon as i installed the first lifepo4 in parallel (with a diode to not backfeed the lead) it was able to start that AC which has a startup surge of over 300a. I now have 3 lifepo4s in there and no longer have the lead in parallel (through diode) since the 3 lithium batts can start the rooftop ac and that's the biggest load it'll ever see. My highest continuous draw would usually be 60-100a. I have never tried to 5kw out of this inverter and i possibly never will because i don't really ever intend to upsize the cabling to the extent required to support that.
I would go with the 2 x 100ahs in order to have some redundancy and the greater likelihood of getting 200a worth of bms's. Also consider the 'overload' behavior of the 2 bms vs 1. It's possible that the overload current from two bms's (the current they will allow for X seconds before shutting down) is WAY higher than the overload of a single bms with same 'continuous' rating. I dont know, im just saying look at it. And honestly unless you are running ACs off it i would wait to plan theoretical further expansions until you've lived with it for a minute. Talk of needing more than 2 x 100ah batteries really depends on what you're trying to do with it.
When I initially put that inverter in the RV it would not start the ~12k btu rooftop ac (i actually dont know the BTUs, it is 12-14k-ish) off the 2 lead acids in the RV because of drops in the cabling (one batt 3ft from inverter, other one 12ft, through existing 2ga cabling). As soon as i installed the first lifepo4 in parallel (with a diode to not backfeed the lead) it was able to start that AC which has a startup surge of over 300a. I now have 3 lifepo4s in there and no longer have the lead in parallel (through diode) since the 3 lithium batts can start the rooftop ac and that's the biggest load it'll ever see. My highest continuous draw would usually be 60-100a. I have never tried to 5kw out of this inverter and i possibly never will because i don't really ever intend to upsize the cabling to the extent required to support that.
I would go with the 2 x 100ahs in order to have some redundancy and the greater likelihood of getting 200a worth of bms's. Also consider the 'overload' behavior of the 2 bms vs 1. It's possible that the overload current from two bms's (the current they will allow for X seconds before shutting down) is WAY higher than the overload of a single bms with same 'continuous' rating. I dont know, im just saying look at it. And honestly unless you are running ACs off it i would wait to plan theoretical further expansions until you've lived with it for a minute. Talk of needing more than 2 x 100ah batteries really depends on what you're trying to do with it.
