Replacing the battery in LEGO Energy meter (set 9688)

Photos and experiment from Maksym Lesenko


After some usage, the rechargeable NiMH battery starts to lose capacity (reduced working time). After that a warning  triangle starts to appear on the display unit, and working time decreases to max 2 sec

To open the battery I drilled the rivet heads and using heating iron carefully extracted the body of the rivets from the battery case.

Inside the battery box I found a typical 9v rechargeable battery inside. This battery must be changed with a battery of similar characteristics (NiMH 150mAh). 

After battery replacement the box is reassembled and secured using typical 2x10 mm screws with 4 mm heads to replace rivets.