After a close encounter with a hedge last Sunday night due to my Deal Extreme light going out unexpectedly, I thought I'd take a look at the batteries to see if there was a problem.
This may apply to other brands as well.....
The light uses a 2s2p config of 18650 cells for 8.2v, I found a cell in each of the series pair to be low at 3.66 volt and the other two to be high at 4.25 volt. A large imbalance that if left alone would damage the cells further or may be worse under charge. I was suspicious that something was up during charge as it seemed to finish very quickly.
I charged the low cells to 4.1v using an RC Turnigy charger and then discharged the pack to 50% using the light. Then I fully charged the two banks of cells but used the parallel pairs to do so.
So as I can check for imbalance in the future I've added a JST 'balance' lead wired so I can charge the parallel pairs separately if needed....
Pack and 'common lead' wired in:
There's a cct board at one end that seems to provide LVC detection for the pack but no balancing for the cells, I tapped into the B- and B+ tabs to create to charge flying leads to be used in conjunction with the common connection.
Wrapped it all up with insulation tape and put it back in the velcro bag:
Cells are now at 4.1v, will note if they become unbalanced again.
This may apply to other brands as well.....
The light uses a 2s2p config of 18650 cells for 8.2v, I found a cell in each of the series pair to be low at 3.66 volt and the other two to be high at 4.25 volt. A large imbalance that if left alone would damage the cells further or may be worse under charge. I was suspicious that something was up during charge as it seemed to finish very quickly.
I charged the low cells to 4.1v using an RC Turnigy charger and then discharged the pack to 50% using the light. Then I fully charged the two banks of cells but used the parallel pairs to do so.
So as I can check for imbalance in the future I've added a JST 'balance' lead wired so I can charge the parallel pairs separately if needed....
Pack and 'common lead' wired in:
There's a cct board at one end that seems to provide LVC detection for the pack but no balancing for the cells, I tapped into the B- and B+ tabs to create to charge flying leads to be used in conjunction with the common connection.
Wrapped it all up with insulation tape and put it back in the velcro bag:
Cells are now at 4.1v, will note if they become unbalanced again.
