It sound as a bad battery or battery connection.
1. You can start by Measure the battery voltage on Controller during load and compare to total cell voltage (measure on
BMS). Large difference=bad connection. If it looks OK continue to next step.
2. Find an electric load that will operate continuously (not motor) at 2 A minimum. I use two 1000W floodlight lamps for 220 V in parallel but ovens also work but do not operate switches or thermostats as DC will damage contacts if opened during load.
3. Fully charge battery at room temperature, not in warm air.
4. Measure voltage over each cell set (cells in parallel). This is easy using two small voltage probes on
BMS board. Write down cell voltages with room for two more sets of measurements.
5. Connect fixed load and wait five minutes. Then repeat measure and write down cell voltages in a second column.
6. Then wait until the
BMS disconnects load. This indicate that a cellset has reached minimum voltage.
7. Disconnect load and measure cell voltages a final time.
You will likely see that one or more cell sets need replacement. If not, post your findings here.
Good luck!
8. See if the voltage goes below the average on one or more cell sets.
minimum the controller require.
