Rewrapping a battery


The above battery cannot be used anymore, it will short and might explode.
The wrapping will sometimes break, luckily it is a fairly simple operation to fix it.

Tools and parts needed


I am using shrink wrap to repair the battery, due to the heat gun I uses, I have selected a low temperature type.
When flat it is 29.5 mm wide, the inner diameter is 18.5 mm, it will shrink at 80 Deg. C.
I bought a roll with 25 feet (7.6 meter) on ebay for $11 (Sellers name is atop_authentic_auction). This roll will last for more than 80 batteries. Fasttech has heat shrink in 1 meter pieces for less than $1.
This heatshrink is also fairly thin, this is an advantage for some lights.
Often heat shrink is specified in width of the flat tube, the table below shows the minimum sizes for different battery sizes.


As a heat gun I uses a hair dryer, it is not the perfect tool for the job, but it can be used.


I do also need something to measure with, my digital caliper is fine for that (A ordinary ruler could also be used).
With a caliper, remember to cover the jaws or it will short the battery.


To cut the heat shrink I uses scissors.



I want the heat shrink tube to be about 3 mm longer than the battery at both ends, with a 68 mm battery this means 74 mm tube.


The new tube for the battery has been cut of the roll.


I uses the fingers to removing the old heat shrink, using a knife or scissors is unsafe.
If there is two layers of heat shrink, only remove the outer layer.


The "naked" battery, do not try to bend the protection pcb out to get a look.


Putting the new heat shrink onto the battery.


There will be about 3 mm extra at each end.

Shrinking Shrinking2

Applying heat, rotate the battery and swipe the heat gun back and forth. If using a real heat gun, be careful with the fingers holding the battery!
It is possible to increase the temperature by covering part of the air intake on the heat gun (This might also melt the gun if overdone).
The battery must not be heated much (As long as it is possible to hold it, the temperature is fine). This is usual not a problem, the heat shrink will shrink long time before the battery is heated.

Final result

DSC_1798 DSC_1797



With a new covering, the capacity information is gone, to fix that I have added a label with capacity. I also included the date I got the battery.