Capacity Test @ 25% of 304ah?!?

[Shep]

I tried my first capacity test yesterday and it shut off way earlier than expected. In the capacity configuration "my cell minimal voltage" is actually 2550 mV or 2.5v. My under voltage cutoff is 2550 so I don't understand why I have zero triggers and power supply that won't deliver power to this battery?
I have the fan's load ready to cut off at 2.5v as well.
One issue I had this time around with these bms settings - is that it was showing me 0% SOC the whole time, even though the whole pack was charged up and at 14.26v.

Did I do something wrong here? How would you troubleshoot this? I feel like it's gotta be my newbness. Thanks for looking and reading!

Trevor

 

[Shep]

My minimal voltage hit was only 13.08v, around a 50% depletion. So confused! Oh And that single cell undervoltage was there before I started the test actually! So ignore that at the bottom of my bms reading for this test.
It couldn't be that the balancing cells always function is on, or could it? I changed that and didn't think of it's effect on capacity testing.

 

[Shep]

Bonehead mistake! The capacities were off somehow. I checked after I did a reading from the bms! I believe it was around the 50-70% range, which would likely explain why my battery stopped charging right there! Not sure how with happened, but likely from the way I input it or that it was received by the bms when writing it to the bms.

Had a whole new issue come up though as well! My fancy heater didn't give me any juice! It recognized that I had a battery hooked up to it showing it's voltage, but it wouldn't turn on! What the heck.
Now I'm running a desk fan and work lamp at 40a from a 1200 watt inverter with the ground stuck to a metal stake in the ground outside. Should be getting some accurate results in about 4 hours! ? Bummer that I don't have the readings from that little machine, but it's nothing I can't calculate myself. To bad the Amazon return window is closed! I suppose it's worth the price to try these little do-dads to make sure we get our setups up and running to our liking.

Hoping all of these cells check out fine. It seems that they are good so far, within .005 of each other and spanning .01 in their total range ( at the moment which is at 58% capacity). We'll see!

 

[Super Dave]

Hi Shep. I came across your post regarding your capacity test and thought I'd piggy back off of your experience thus far if you don't mind.
I just received a 400ah battery from china and want to get an accurate capacity test as lifepo4 batteries bought from china can be a hit and miss sometimes with respect to getting what you paid for. I bought a capacity tester similar to yours and did 2 tests but I'm questioning the results as I'm not entirely sure I had my bms configured properly. It's funny how many videos there are showing capacity testers and how to use them but I couldn't for the life of me find a video on what to set the bms parameters to achieve an accurate result. And of course, the bms parameters are critical as you indicated.
Were you able to ultimately set your bms and achieve an accurate result. If you wouldn't mind sharing the settings you used I'd appreciate it.

Thanks, Dave.