Batteries
I have a 2021 Thor Omni 4x4 sv34. I am replacing the two lead batteries most likely with lithium with BMS. Any recommendations would be greatly appreciated. Thanks
Forum Discussion
Most retail lithium 12v batteries are going to be capped around 100-200amps (continous vs peak load) before he BMS cuts power. If this is for the starting batteries, that's not viable as a big diesel engine can ask for 800-1000amps or more.
If it's for the house batteries, lithium is great but the charging gets more complicated. Lithium and lead-acid want different charging voltage and amperage. So if you want the alternator to charge the house bank, you need a separate charging circuit that is able to take the power off the alternator (or thru the starting batteries), adjusts the voltage and feed it to the lithium. If you put in a good size solar array, it is possible to simply disconnect the house bank from the alternator side of the 12v system (or if you never boondock, but if you are always on shore power, you don't gain much of anything going to lithium).
Most retail lithium 12v batteries are going to be capped around 100-200amps (continous vs peak load) before he BMS cuts power.
more and more are coming out with higher numbers now. 5 years ago this would have been true, but as more retail are going into the 200, 300 and larger banks the BMS are getting quite a bit higher. and the peaks are not just double the continuous anymore. I just watched a test where the Over current functioned to 700A mind you it was a less than 1 second shutdown but the 100a bms did 220 amps continuously. so that was a little different.
take Battleborn or dragonfly or over priced batteries, what ever you want to call them there 270AH battery is rated for 300A continuous.
look at the cheep redodo its 100amp battery is rated for 100 amp continuous but 300A for 5 seconds.
To get the high amp batteries, you will be paying 3-5 times the price. Of course, the 300A 270ah battleborn is going to be roughly what 3 100a 100ah generic batteries can supply (balancing between batteries might drop the total a bit).
But even 2 of the battle born batteries are going to peak around 600amps...not enough to turn over a big diesel engine.
I would never buy a battle born myself, way over priced. I picked them as an example because I was looking at it in the rv shop while I was looking for something else. its less AH as mine and over 2 times the size. it does have a larger capacity BMS though but that's because I chose mine so I could not go over 0.5C on the discharge my point was that you could buy say a 300amp redodo and it is less the cost of three 100am redodo's and has a 200A BMS so for the average unit that has a 2000watt inverter or less this will do just fin and give them three times the usable capacity of a couple GC2 batteries and they are not much larger than a standard battery if you find the right brand that is making the new 300AH mini's
The point is even top of the line very expensive batteries will struggle starting a big diesel.
A couple of cheap and cheerful 12v 100amp lithium should handle a 2000w inverter even with a surge load. They may be a bit weak in terms of how long they will support the load but most people aren't running loads in excess of 1000w for more than a couple minutes (aka: warming something in the microwave). If you are trying to run aircon for hours, you are going to need a bigger battery bank.
