I completed assembling my ebike and made the first road test on 13July (http://ebike.ourpix.biz). Then, for four days the following week, made the 31km round trip to work.
Battery charging issue (for details refer: http://det-hem.ourpix.biz/v/places/vehicles/ebike/charger/ )
Symptoms. System cuts out under medium load (earlier than expected). After recharging the battery for the third time, the BMS cut-outs on even light load. (could be BMS or Controller? low current or low voltage?). As soon as cut-out, battery voltage indicator shows high (unloaded) and recovery is within a couple of seconds. (can leave throttle on full and motor drives again after 2 seconds, cutting out again 3-5 seconds later when on load).
Problem Description. Before recharging, I removed the cover from the battery and measured the unloaded voltage across each cell. All except two registered between 3.27v and 3.31v. Cells 9 & 10 both registered only 2.98v.
Test Procedure.
I connected the charger and allowed charging for 10 hour. The images at http://det-hem.ourpix.biz/v/places/vehicles/ebike/charger/ record the voltage across each cell.
Cell 07 was overcharging whilst cell 08 is undercharging. Cell09 and cell10 don't appear to be charging at all. During this charging cycle, they lost charge, dropping voltage from 2.98v to 2.56v and 2.53v.
When I applied 3.7v to cell 09 it drew 3A, and 5A at 4.4v. After 1 hour at 5A cell voltage was at 3.4v from 2.6v. I brought cell 09 and 10 up to 3.4v each and then applied 12v across cell 08 to 10 which charged all three cells at 4A. After 20 min the voltage across cell08 was 3.7v whilst cell09 3.51v and cell10 3.47v. I removed cell08 from the circuit and applied 4A to Cell09 & 10. 10 minutes later, cell09 was at 3.65v. I then applied 3.7v to cell10 for another 30 min bringing it to 3.65v.
When charged on their own, cells 09 & 10 appeared to charge OK. Next test - drain battery.
I loaded the battery with 4 23watt 12v globes in series (ie: approx 2A).
0 hrs: Loaded cell voltages ranged from 3.27v to 3.15v.
2 hrs: Loaded cell voltages ranged from 3.24v to 3.09v.
At approx 4hrs one globe blew and without a spare I was unable to measure the loaded voltage. The battery had drained approx 7-8AH. Unloaded voltage of all the cells was 3.29v.
The charger. The charger is effectively 16 little switch mode supplies in series with connection to each cell via a 17 pin plug.
http://det-hem.ourpix.biz/d/33927-2/P7190255.jpg
http://det-hem.ourpix.biz/d/33924-2/P7190252.jpg
* Unloaded voltage across each stage of the charger was 3.64v.
* Continuity checked OK between charger PCB and plug pins.
* Continuity checked OK between charger PCB and BMS.
Root Cause: ??
- suspect charger cutting out too early on cells 09 & 10
What next?
Battery charging issue (for details refer: http://det-hem.ourpix.biz/v/places/vehicles/ebike/charger/ )
Symptoms. System cuts out under medium load (earlier than expected). After recharging the battery for the third time, the BMS cut-outs on even light load. (could be BMS or Controller? low current or low voltage?). As soon as cut-out, battery voltage indicator shows high (unloaded) and recovery is within a couple of seconds. (can leave throttle on full and motor drives again after 2 seconds, cutting out again 3-5 seconds later when on load).
Problem Description. Before recharging, I removed the cover from the battery and measured the unloaded voltage across each cell. All except two registered between 3.27v and 3.31v. Cells 9 & 10 both registered only 2.98v.
Test Procedure.
I connected the charger and allowed charging for 10 hour. The images at http://det-hem.ourpix.biz/v/places/vehicles/ebike/charger/ record the voltage across each cell.
Cell 07 was overcharging whilst cell 08 is undercharging. Cell09 and cell10 don't appear to be charging at all. During this charging cycle, they lost charge, dropping voltage from 2.98v to 2.56v and 2.53v.
When I applied 3.7v to cell 09 it drew 3A, and 5A at 4.4v. After 1 hour at 5A cell voltage was at 3.4v from 2.6v. I brought cell 09 and 10 up to 3.4v each and then applied 12v across cell 08 to 10 which charged all three cells at 4A. After 20 min the voltage across cell08 was 3.7v whilst cell09 3.51v and cell10 3.47v. I removed cell08 from the circuit and applied 4A to Cell09 & 10. 10 minutes later, cell09 was at 3.65v. I then applied 3.7v to cell10 for another 30 min bringing it to 3.65v.
When charged on their own, cells 09 & 10 appeared to charge OK. Next test - drain battery.
I loaded the battery with 4 23watt 12v globes in series (ie: approx 2A).
0 hrs: Loaded cell voltages ranged from 3.27v to 3.15v.
2 hrs: Loaded cell voltages ranged from 3.24v to 3.09v.
At approx 4hrs one globe blew and without a spare I was unable to measure the loaded voltage. The battery had drained approx 7-8AH. Unloaded voltage of all the cells was 3.29v.
The charger. The charger is effectively 16 little switch mode supplies in series with connection to each cell via a 17 pin plug.
http://det-hem.ourpix.biz/d/33927-2/P7190255.jpg
http://det-hem.ourpix.biz/d/33924-2/P7190252.jpg
* Unloaded voltage across each stage of the charger was 3.64v.
* Continuity checked OK between charger PCB and plug pins.
* Continuity checked OK between charger PCB and BMS.
Root Cause: ??
- suspect charger cutting out too early on cells 09 & 10
What next?
