Multitool battery fix

The problem

Someone gave me this multitool as it was reportet it was a bit unreliable start wise.

-20230804

Did some random tests to see if I could replicate the problem.

Flashing light = nok ?

Teardown

Fearly straightforward, some screws and the casing could be split".

Time to split

Inside of the casing the layout is very simple, no fancy electronics.
Perhaps a voltage sensor and current sensor.
Mosfets are used instead of a relay or mechanical battery connection.

Only DC motor, almost no brains.

Some measurements

Quick continuity check to see if connections are ok.
No errors could be found.

Motor tabs and testpoints.

No PCB error or broken traces coud be found, time to check the battery.

The cell check

Assembled the halfshell and tested with battery, now the issue became clear.

Bluetooth battery tab.

PCB battery tab broken.

Seems the battery weld tab has snapped, perhaps it ha been dropped one too many times.

Bluetooth battery tab.

Removal of the cell is not possible without breaking more of it.
Perhaps fix can be done with a bypass.

Full view, broken tab.

for some current handling option, solder wick will suffice.

Solder wick, perfect as a fix.

Soldered in, 50W PTC iron used.

Carefuly reassembled, dont want to short curcuit anything.

It's alive!

Powers on and runs = ok

-20250810

Update

Used in Kitchen cabinets a lot. Still working fine.