Project:Semi-Cordless Drill

ProjectInfoBox Semi-Cordless Drill
Status:	working, but not perfect
Release Date:	Sep 2017
Initiator:	Lukas
Materials Used:	old battery pack, power supply, zip ties
Tools Used:	cordless drill, soldering iron
Approx. Cost:	about 30 €

One of my cordless drill NiCd battery packs couldn't hold a charge for more than five minutes anymore so it had to go. But I kept the platic case and the push connectors and wired them to a power supply! The drill (Bosch PSR 960, but the concept can easily be transferred to any model) can still be used with a good battery pack as before, but you can easily switch from cordless to corded mode depending on your needs (or if you're just to impatient to wait for that charger to finally get its job done).

The first working version is usable, but you have to accellerate with a bit of caution or it stalls. Perhaps a capacitor can mitigate this effect, and I might also add some fancy LEDs when I open it up again...

Measure Consumption

At first I tried to find reliable information about the battery properties from the label and online, but then Patrick just helped me find out how much power the motor consumes by hooking the drill up to a adjustable power supply.

We arrived at an estimate of <?> A.

(From initial calculations: <?> A)

Removing the Battery

Only the battery pack's plastic casing and the connector plate was needed for this project, the old NiCd cells needed to go. For this model, the case was held together by four screws. One of them was hidden under a plastic plug which was carefully drilled out with a twist drill bit so I could tamper with the internals.

Once open, the case revealed 8 cells wired in series as we knew from measuring.

<More details to follow>