When Not To Let Your AIO Communicate With The Batteries

[Ellcon123]

Voltage is a good gauge of SOC. You know when the battery is full or empty. Everything in between is a bit of guesswork and requires coulomb counting. BMS settings high and low should be last resort fail-safe settings. If the battery didn't charge after LVD then I'd say it's a dodgy BMS. BMS should reconnect if charge current is present.

As for potential ageing issues with full charge, I'll worry about that when someone reports they've reached 5000+ cycles. My system is there to be used so future problems are just that.

 

[Kornbread]

Since it appears most bms passively balance the cells, I can see it taking longer to balance at a lower voltage. After several days of partly cloudy weather and shade due to Mr. Sun moving South for the winter, one of my batteries went into LV warning even though the aio was set 10% above the battery's LV alarm. SOC for the battery bank was something like 38% when the one battery alarmed out, which should't happen till 25%. Pretty sure if I hooked the laptop to the battery bank and looked at individual cells, there would be some rather large imbalances. Don't think the battery bank has been over 54v long enough to get a good cell balance.

To further extrapolate this train of thought. As far as the eg4 LiFePo4 is concerned, it is said they do not use grade A cells, although, they are advertised as using grade A cells. It has also been discussed on many threads here, very few of the advertised grade A cells are actually, grade A as most are seized by the EV market.

1 + 1 = 3 right?

It is my opinion that due to the 1) eg4 not using grade A cells, 2) combined with poor matching between cells in a battery pack, 3) and the advertising lure of more is always better, the high voltage settings in the bms are there to help compensate (balance) for poorly matched cells ... and of course, advertising copy.

YMMV