SOC not always accurate on Pace Bms ( maybe others too ? )

[Lardino]

I made a video showing my evaluation of SOC readings from Pace Bms used on my Jakiper / Orient Power batteries. My observation is that after a few days where the batteries don't totally fill up all the way the SOC gets off and should not be relied on. It could also be caused because the Pace Bms does not see smaller current around half an amp. It isn't such and issue if the batteries fill up every day. But last winter , my first time using the lithium batteries I wondered which SOC was accurate - the SOC reported by the batteries, or the SOC reported by my Midnite Solar Charge controller. My conclusion is that the Midnite is very accurate looking at all 4 batteries compared to BMS reported SOC. My batteries shut down last winter on UVP under volt protection because I was believing the bms SOC. Had I understood more at the time I would have seen the batteries cells were low because the differential began to spread apart . This year after much reading and watching lots of Off Grid Garage videos I have a much better understanding of how lifepo4 cells behave. I tried to explain in this video why the SOC is off based on the voltage and current .

 

[SeaGal]

My observation is that after a few days where the batteries don't totally fill up all the way the SOC gets off and should not be relied on.

TADTS

 

[BentleyJ]

OMG, had to Google that one. First 5 results were for Texas Alcohol & Drug Testing Service. I knew that wasn't it.

 

[Bob B]

? ..... Reminds me of when my daughter was younger and I used to make up my own acronyms when texting here .... She would get ticked off because what I made up wasn't an official acronym .... so, of course I would make up more of them.

BYTADT and it's a common complaint. The newer JK BMS have some setting to make it easier to keep in sync, but you have already discovered the tried and true method of occasionally doing a full charge.