I have two sets of BYD 13.8s with a 15000 Quattro and today have noticed the state of health of the batteries at only 66%. This is not a figure a looked at before but with the batteries being only 7 months old is there anything I should be doing to get them back to 100%?
I have solar and a generator to charge them. They were charging at the time I took these screenshots, initially at about 5kw (first pic) then higher current 10.7kw.
Maybe the cells are out of balance?!
I would try to charge the batteries to 100%.
It has just finished charge to 100% but still showing 66% state of health ?
Let it charge a while longer, it takes a while to balance the cells (if it is the problem).
If that doesn't solve the problem you should get in touch with the seller of the battery.
I asked Freedomwon the question 'when should I be worried about SOH' and their reply to me basically boils down to the fact that it looks at a few variables and the biggest contributors seem to be cell balance and how often you charge to 100% or not. Just give it a few days to balance properly and do a few proper cycles back to 100% and I am sure the SOH will increase. Oh, according to Freedomwon, anything below 70% they would start looking at why that happens, perhaps BYD is similar.
A quick update regarding this issue, I have been working with Anthony at Bimble Solar and BYD and found that one of the BMS units was faulty which is why my SOH was down at 66%.
The faulty BMS unit has now been replaced and all is well, back to 99% SOH.
Massive thank you to Anthony Brennan who contacted me directly about this issue and helped diagnose the fault. BYD support is fantastic and very efficient .
It would be good to have the process of finding the issue is public in case of someone running into the same problem.
It was simply a case of isolating each battery bank individually and reviewing the SOH on each bank, one bank was reading 100% and the other 32%. We ran individual banks for a couple of days and monitored SOH. It was clear which battery bank was at fault.
BYD actually diagnosed the fault with the help of Anthony @Bimble Solar.
