I'm using a Daly 20A commonport BMS for my 8s 24v LiFePo4 battery (charging it with my Rhenogy + 1 solar panel). Charging seems to go fine, and it handles my 230v inverter up to 500W as per testing.
However, when I connect it to my mobility scooter - its intended use - and try to drive, it will cut out within a second. I have to disconnect the battery and reconnect, and it comes back alive.
Did some measurements to see if I'm not spiking the inrush current (even though the spec-sheet says 60A sparkle current), and my findings are:
- Voltage doesn't drop more than 0.2v before the BMS cuts out. From 26.3 to 26.1. I see no transients
- Amperage drawn is 0.7A when the BMS cuts out
- If i feather the throttle so it stays below 0.5A, it sloooowly starts to move but as soon as it picks up speed and exceeds 0.7A, it cuts power.
- If I connect the battery such that I bypass the BMS (directly on the battery -+ clamps), the scooter works absolutely fine for the entire day
- When it cuts, the battery voltage drops from 26.3 to 0 and then 0.5v, until I disconnect the battery upon which it jumps back to 26
Also, when connected to an inverter, the BMS runs >10A comfortably to my power drill. Haven't managed to cut it out, so it seems to be something the scooter is doing to trip the BMS up.
Which things can make a Daly low-power BMS cut out? My understanding is either low voltage on one of the cells (not applicable) or overcurrent (>60A seems much, since it's not inrush current either).
Any ideas?
However, when I connect it to my mobility scooter - its intended use - and try to drive, it will cut out within a second. I have to disconnect the battery and reconnect, and it comes back alive.
Did some measurements to see if I'm not spiking the inrush current (even though the spec-sheet says 60A sparkle current), and my findings are:
- Voltage doesn't drop more than 0.2v before the BMS cuts out. From 26.3 to 26.1. I see no transients
- Amperage drawn is 0.7A when the BMS cuts out
- If i feather the throttle so it stays below 0.5A, it sloooowly starts to move but as soon as it picks up speed and exceeds 0.7A, it cuts power.
- If I connect the battery such that I bypass the BMS (directly on the battery -+ clamps), the scooter works absolutely fine for the entire day
- When it cuts, the battery voltage drops from 26.3 to 0 and then 0.5v, until I disconnect the battery upon which it jumps back to 26
Also, when connected to an inverter, the BMS runs >10A comfortably to my power drill. Haven't managed to cut it out, so it seems to be something the scooter is doing to trip the BMS up.
Which things can make a Daly low-power BMS cut out? My understanding is either low voltage on one of the cells (not applicable) or overcurrent (>60A seems much, since it's not inrush current either).
Any ideas?