Testing/Fixing Cree T6 battery packs

[103Alex1]

Readings doing that are as above :

1st & 2nd - 3.77V

3rd & 4th - 4.22V

 

[Deleted member 4366]

It's possible that the short in the wires has knocked it out of balance, or maybe even damaged the BMS. Whatever, you need to charge it up manually to get it back in balance. If you haven't got a 4.2v charger, try an old 5v phone charger, but keep an eye on the voltage, which will climb faster as it goes past 4.2v.

 

[103Alex1]

It's possible that the short in the wires has knocked it out of balance, or maybe even damaged the BMS. Whatever, you need to charge it up manually to get it back in balance. If you haven't got a 4.2v charger, try an old 5v phone charger, but keep an eye on the voltage, which will climb faster as it goes past 4.2v.

I've got a 2 channel 3.7V charger for 18650 batteries from Ultrafire which charges cells to 4.2V and then cuts off... but you have to insert the cells into the slots - which I guess means dismantling the whole pack and unsoldering all the tabs / PCB ?

Is dismantling the pack the only way to do it ? The cells seem glued together and also I can;t see what has been used to attach tabs to ends of cells to put it back together. Still seems to work to power the light but I guess will cut out prematurely when the undervolt pair reach LVC ?

 

[103Alex1]

I've just looked up about the tabs and seems I'd need a tab welder to fix them back :

Battery Tab Welding | Model Flying

So am I right in thinking I cannot charge the individual cells any other way than removing the tabs to allow them to be individually charged and then having a special tool to fix them back ?

 

[Deleted member 4366]

Is it possible to squeeze the pack into the charger so that two parallel cells are in. If not, make a dummy battery, and run two wires to the low cells. Cut a bit of a tree branch or something similar of the right length and diameter, and jam the wires at the top and bottom of it in the charger, then you can jam the other ends behind the appropriate strips on the pack.

 

[103Alex1]

Is it possible to squeeze the pack into the charger so that two parallel cells are in.

I can squeeze 2 cells at a time into the charger. Should it be the pair which are each reading the low voltage when measured individually with probes on the cell contacts behind the contact strips ? (get confused by the parallel thing !)

... but of course I can't help the charger making contact with the contact strips as these run right across each end of the cells ....

 

[103Alex1]

Gave it a go inserting the 2 duff cells into the 2-channel 4.2V charger but the contact strips made contact with the charger terminals and blew the charger.

Think I may just ditch this pack and replace it ... getting at the cells and reinstating is not straightforward.

Had a think about those nickel strips - can they be soldered back on to the battery ends of some decent new cells or are the batteries too much of a heat sink for this to work ?

It's probably easier in the long run just wiring in your lights to main battery for fit-and-forget. A benefit of riding self-builds or out-of-warranty bikes !