Trying to revive an old AED battery pack

This is my first blog post in ACC and is about a battery of an old FR2+ AED machine that I had laying around. The battery is not rechargeable thus after gone low it is practically useless so I tried to give back some life to it.

At first, I had to make an opening since the pack was sealed thus I cut the sides with a rotary saw. In the inside the battery pack is welded together in 3 rows of 4 3V LiMnO2 cells. The bottom side is connected through a wire to the PCB that has the pins going into the AED machine and the top side connects the 3 rows with 3 diodes and then a thermal fuse and a component that I wasn't able to identify, and then it connects to the pin breakout PCB.

Finally trying to revive the AED machine I removed the battery pack and circuit from the PCB and connected two cables on + and - side of the board of which then I passed out of the other side of the battery pack through a small hole I drill.

By connecting to the cables to the power supply I managed to get the device working again with the voltage input of 12V-13V, however I keep getting a "low battery" notification which is quite annoying.

The pictures of the tear-down are shown below and if anyone has a suggestion on what to do in order to remove the "low battery" notification please leave a commend!








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