CHINS 12V 300ah LiFePO4 reading over 17 volts

[RFLOYD99]

Hello everyone, just finished upgrading to a 48V solar system for my off-grid home after running for the past two years on 24V. I have a mixture of 12V 300ah batteries, some are LiTime and some are CHINS. After completing the setup programming on the SP6548 boxes, sun was out and the batteries were doing well. I measured each of the 4 batteries in series... three were at 13.5V and fourth was reading at 17.5V. I nearly had a heart attack!

My guess is the BMS has failed, maybe partially? I thought the cutoff was 15V. Not sure. It's out of its 1 year warranty but still within the 5 years that CHINS says they will service it. I guess for some huge amount of money?

What are my options on this one? Continue to use it but monitor the system closely? Or will I have to move it to the experiment pile and salvage some of the parts?

Thanks.

 

[740GLE]

Can you remove the battery from the string and individually measure it?

What was you’re system voltage when you measured that battery?

Any chance your DMM battery is running low? I had a fluke read 5.3v when measuring a cell and the battery was practically dead.

 

[Robbert]

Hello everyone, just finished upgrading to a 48V solar system for my off-grid home after running for the past two years on 24V. I have a mixture of 12V 300ah batteries, some are LiTime and some are CHINS. After completing the setup programming on the SP6548 boxes, sun was out and the batteries were doing well. I measured each of the 4 batteries in series... three were at 13.5V and fourth was reading at 17.5V. I nearly had a heart attack!

My guess is the BMS has failed, maybe partially? I thought the cutoff was 15V. Not sure. It's out of its 1 year warranty but still within the 5 years that CHINS says they will service it. I guess for some huge amount of money?

What are my options on this one? Continue to use it but monitor the system closely? Or will I have to move it to the experiment pile and salvage some of the parts?

Thanks.

I would not use that battery. That's over 4 volts per cell and ready to fail.

 

[mikefitz]

If the batteries were measured whilst still in series it's probable the BMS in the high volt battery was in protection mode.
Four 12v batteries is series will eventually cause issues unless the batteries are balanced with battery balancers.
My guess it your charge voltage is too high and the problem battery detected cell overvolts and disabled the charge path.

https://www.amazon.com/Battery-Equalizer-Balancer-Supports-Trolling/dp/B0CLTZ2XQX/ref=sr_1_1_sspa?crid=1F9U83HZJJNTG&keywords=Battery+balancer&qid=1707084302&sprefix=battery+balancer%2Caps%2C408&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

 

[CJLDAD]

The BMS was probably in cell over voltage protection.. Take it out of series and check it.. I would guess it will drop right back down to a "normal" voltage..

 

[RFLOYD99]

Thanks for the replies. I've been using this battery in the 24V system for a couple of years. The string of batteries appears to work fine when I turn on the loads at the breaker panel, so I was thinking in a protection mode the battery would not contribute.

Thanks for that link to the Battery balancer. I'll take a look.

 

[RFLOYD99]

Just a follow-on ... the suspect battery does seem to be a little higher than the other three while operating, but only by about 0.15 Volts. The others are almost exact +/- a few millivolts.

During the daylight charge today, I noticed the same issue. That battery was going above 15 volts while the other three were within nominal, about 13.5V. So definitely some issue with the BMS. A replacement will set me back $800-$900 so I am going to set the max charge to 56V and the float to 54V. Have to report back in a few days. It will likely hit 15V each day. Still high and probably knocking days off its lifespan but poor folks have poor ways.

 

[740GLE]

A battery balancer should help that out as well.

 

[WorldwideDave]

report back - did the battery balancer solve your issue @RFLOYD99 ?