Hi guys and gals, just wanted to share an issue I just had with my Renogy LiFEPo4 batteries purchased in May of 2019. These are not the new version they just released with cold temp protection. Anyway, I use these in a parallel setup with the Victron BMS-712 in our Arctic Fox 811. I use an old modified sine wave 2KW to power our microwave and our really cool one cup Keurig maker. Anyway, I've noticed twice now that my batteries, which are usually fully charged at the end of a return trip home as I have the Redarc https://redarcelectronics.com/products/dual-input-40a-in-vehicle-dc-battery-charger powered from the truck charging system while driving. This supplies a good 40A, or 20A per battery charge while driving. Soooo, twice now, The batteries have lost their charge, I mean lost, all the way down to 10.2VDC, or just above the automatic low voltage cut off from the Renogy internal BMS. I looked for parasitic loads and found none, so I suspected one battery might be loading down the other. I went ahead and manually recharged the the pair and then watched the voltage closely and it began to drop almost immediately. To trouble shoot I disconnected them from each other and while one was at 13.2VDC, the other remained at 10.2VDC. The later would not charge as my smart charger would immediately ramp the DC voltage up as if the battery was nearing full charge I am thinking it did this because the current draw of the battery only reached 0.2A. I tried several different chargers I have and all pretty much did the same with the final voltage only 10.9VDC. Renogy just sent me a pre-paid UPS label and the battery is on its way back to them. They say they'll need to confirm my findings, but suspect an "open" cell. I really had no issue with them as far as their service, only took a day or two to get the RMA and shipping label. We'll see what they do, but I am hopeful of good service. Any ideas of what might have happened here, I am open to comments for certain! Attached is the Victron monitoring results, the start is with both batteries and the change is when I remove the good battery from the pair and leave the bad battery charging.
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