This instructable deals with replacing the Ni-Cd battery pack in 15+ years old dremel Free Wheeler. Despite its age it's a capable little tool the first job I used it for was cutting the outer roller races from the rear swinging arms of a citroen CX. As it is my father's and he told me to change like for like that is what I've done. There is however plenty of space in the case and it could quite easily have accommodated a 1500mAh 2s Li-po the charging board and a new electronic speed control board, but that's not what he wanted.
An option that has only just come to my attention is there might just be space for a pair of 18650 Li-ion batteries and the necessary charging and speed controller boards, something I am adding here as a reminder to myself for next time.
Step 1: Disassemble
Step 2: Inside
Step 3: The New Battery
My father was insistent that he wanted like for like for replacement if possible, or at a pinch would have gone for nickle metal hydride cells instead of Ni-Cd.
I found a company online www.batteriesplus.co.uk that supplied tagged Ni-Cd cells of the right size (in hind sight I should have paid them a little extra to make a welded pack up)
Using the old pack as reference I arranged the cells in the correct order held them in place with a rubber band then rotated the cells so the tags needed the least bending to make contact. Using a strip of thin card as insulation to avoid burning the plastic sleeves of the cells I then soldered the tags together.
I then cycled the new pack several times using a commercially available battery charger. I've since made a lead to use this charger with the dremel instead of the so called trickle charger which is nothing more than a wall wart.
Step 4: Tag Salvage
No photos available as this entailed tool abuse. I had to salvage the connector tags from the old pack, I did this by working a shall wood working chisel between the tags and the battery case deforming both in the process then once positioned tight against the spot welds a sharp blow with a mallet cut the tag free.
The tags then needed straightening out, and the weld dimples filing off. They were then tinned and soldered into place on the new pack.
Step 5: Refitting
The rubber band was replaced with packing tape, and new side plates cut from a thin card box and stuck in place with hot glue. the new pack was then placed in the case the cables refitted (note the cables are made with next to no free play the tags had to be soldered in the right place in the right orientation for the his to work)
Making sure the switch was in the off position the motor and drive assembly were fitted in position and the other half of the case refitted.