Norelco G370 Hair Trimmer

Introduction

I have a cordless Norelco beard trimmer that began to lose battery life. Eventually it reached a point where the trimmer was not useful because the battery would die so quickly. I've used this trimmer for about 10 years so its time to buy a new one. Right?

Norelco G370 operation

The G370 cuts hair using a scissor action. The blade is connected to a cam that is turned by a motor. This creates a back-and-forth motion of the blade. A Ni-Cd battery is connected to the motor through an on/off switch.

This is a view of the trimmer with the cover removed. The battery is a Ni-Cd 1.2 Volt cell. The motor turns an off-center cam which creates the scissor motion of the cutter.

Repair video

Below is a video that shows the repair process.

Repair details

Battery

The original battery had no distinguishable part number. It is a Ni-Cd cell that is AA sized. The wires are connected via 2 tack-welded tabs. I found a replacement battery from Batteries Plus. The part number is NUN1100-aaf and the price is $3.99.

Link to replacement battery

Soldering

It can be challenging to solder onto a battery because the battery has a large thermal mass. That means the heat being applied by the soldering iron is being distributed throughout the battery. Using liquid flux can help with any challenging solder joint. The flux helps to prepare the surface for accepting solder. I find it works best to first apply solder to both components then join them together. I applied flux to the battery and put some solder on the battery. Then I did the same on the wire tab. Finally I joined them together by applying more heat with the solder iron.

References:

Replacement battery:

NUN1100-aaf

Kester 186 No Clean Flux:

https://www.amazon.com/Kester-Rosin-Soldering-Bottle-Clean/dp/B01MR49JY1