Project 018 – Reverse engineering and simplifying

Battery Charge Indicator

The battery pack of the Arjo Trixie patient lift has a single LED indicator. When operating the patient lift, the LED will flash when the battery needs charging.

The manufacturer of this patient lift wanted to have a more affordable battery pack as the original battery pack was quite expensive. He asked what was possible.

I inspected the battery pack to see what was possible to reduce cost.

Apart from the the batteries themselves, there were two PCBs inside the battery pack, a large one and a smaller one. The larger PCB did the actual the battery voltage measurement and the smaller PCB was only used to mount the LED. The costs of the battery pack could be reduced by looking for cheaper batteries, but also by replacing the two PCBs by one single new PCB with the same functionality.

I made a replacement design for the small PCB around the Microchip PIC10F204 microcontroller. The larger PCB could now be omitted and the smaller new PCB with the LED simply replaced the old one.

Additionally, I built a basic programmer/tester for the production of these PCBs.

Replacing the two PCBs by just one turned out to be a major cost saver.