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My first 14s11p battery charging stopped before reaching 58.8V  

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danlupas
(@danlupas)
Street cred = 10 mAh
Joined:4 months  ago
Posts: 4
29/11/2018 10:40 pm  

Guys, I am charging for the first time the 14s11p battery that I built. The charger stopped at 53.7V instead of 58.8V. I am using a Vruzend 52V charger and matching Vruzend BMS. All the batteries are new and of same type. A few were full and the rest at 3.6V when I started charging. What could be the problem? I measured the voltage from the negative charging cable to +1, +2 .. +14 balancing leads connection and the voltage increases for every measurement with the expected amount so I don't think a series group is interrupted. How can I troubleshoot this? Did a hard BMS reset and it resumed charging for a few minutes and then the charger stopped againand the led turned green. Thanks for any suggestion you may have


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Micah (Vruzend Rep)
(@admin)
Street cred = 5 Ah Admin
Joined:2 years  ago
Posts: 433
02/12/2018 11:03 am  

Could you please measure the 14 parallel group voltages and share them? That can help us diagnose the issue better. I suspect its a balance issue but it is impossible to know without seeing the voltage of each group.


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danlupas
(@danlupas)
Street cred = 10 mAh
Joined:4 months  ago
Posts: 4
03/12/2018 9:17 pm  

Thanks Micah for the reply. The voltage of one parallel group was way higher than the others (4.17V) and the others were like 3.7V. I discharged that parallel group to match the others with a battery discharger/tester with low voltage cut-off and the charging resumed.

It stopped again at 57.1V pack voltage still short of 58.8V. The situation is now the following for each parallel group voltages:

  1. 4.04V
  2. 4.04V
  3. 4.04V
  4. 4.04V 
  5. 4.12V
  6. 4.12V
  7. 4.14V
  8. 4.15V
  9. 4.27V
  10. 4.12V
  11. 4.4V 
  12. 4.12V
  13. 4.20V
  14. 4.4 V

The question is will the BMS take care of  this in a few days by bleeding the higher parallel groups ? The balancing must be triggered since one of the cells at least reached the threshold voltage.

What should I do ? Leave the charger connected ?  I don't like the idea to leave the pack unattended or can I force the cells into balance somehow ( bulk charging to less than max voltage to avoid overcharging any parallel cell ?). Need some sort of 60V+ DC power supply, like from a 3D printer + I have a 5A variable DC step down converter. 

Thanks again for your answer and for your contributions to DIY battery pack community,

Dan

 


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