locked Re: Batteries starting to get weak - MMM - What to do -

Ken Powers SV Aquarius

Hi Scott,

Actually, I only run the AC for 3 to 4 hours because I don't want to cycle the batteries too low, and I also want to save battery for the next day.  If the batteries are full,  I could run the AC all night long.  But, it is still a game changer just to get the cabin cooled down, so I can get to sleep.  40Amps x 10 hours, should not be a problem.

My batteries cost $1800 each, so I spent $3600 on the batteries (plus $500 shipping totaling $4100).  But, for 600AH at 24V, that is an amazing price.  It is almost as cheep as building the batteries yourself out of single cells, and buying a good BMS.  O, and this is cheaper than getting good AGM's.   I would consider using single cells next time where I get to choose the BMS.

I have done a lot of research on LiFePO4 batteries, and catastrophic failure of a LiFePO4 battery is probably rarer than that of lead acid.  You can short them, shoot them, or overcharge them and though they will be destroyed, they are not going to burn.  Today, the weak link in the LiFePO4 batteries is the BMS.  Almost all cells used by any reputable battery manufacturers are, 1) made in China, and 2) pretty dam good.  They should all last about 5000 cycles if used and maintained properly.  



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