Well, did another capacity test with 8 of my Xuba 280Ah EVE cells. Staying on topic, ha ha.
Was aiming for an upper limit of 26.80V. Took some doing again to charge the battery to a steady resting voltage. I'm learning how frustrating CC/ CV charging can be, time consuming when trying to get to a final resting voltage (somewhere in the middle). I let the battery rest overnight and it still dropped to 26.76V. I went with it anyway, close enough. Start of my morning, working from home.
Lower limit was 24V under some load. Got about 61% capacity usage (4,420Wh / 7,168Wh or 172Ah / 280Ah). Was expecting closer to 80% (5,734Wh / 7168Wh). Perhaps it's my testing method. Trying to be more real-world as opposed to perfect testing conditions. The C-rate was up & down throughout the day (183W - 1,500W), averaging ~440W/h (<0.1C) in about 10 hours. Fridge would kick on & off, brief coffee warm-ups with the microwave, lunch break, etc....
1st Pic - Begin test, Inverter off, resting voltage, 26.76V, cells reasonably balanced
2nd Pic - Inverter on, minor drop in voltage
3rd Pic - Running home office, Frig, & coffee maker, 1.5Kw peak for a few minutes
4th Pic - Hit lower limit of 24V under load
5th Pic - Powered everything off, Inverter still on, voltage recovers a bit
6th Pic - Inverter off, resting voltage 24.29V after half an hour or so
I was using the ISDT BattGo meter (right) voltage as reference, as it matched closest to my hand-held multi-meter (not-shown). Using Drok meter (middle) for total Wh or Ah. There's a little voltage offset between meters, but all are in the same time-line. Perhaps I should use the inverter voltage instead. It tends to be the lowest compared to the rest.
