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Re-Use, Individual Cells from 18V NiCad Answered

Seems that with a bit of randomnity in mfging, some cells in an 18V battery might fail before others. With that in mind, I'm trying to re-use individual cells after a pack craps out. 

Test 1  Battery pack from a "drill master" which I got for  ~$2 at a thrift store. Google informs that this is a harborfreight tool, so expectations are low.  Upon disassembly of the pack, 1 of the spot-weld connections between cells had broken.  Since I don't currently have a 1.5v source, I'm using a 3v  source to charge 2 cells in series. Only charging for a few minutes at a time. Currently, this 2 cell set will light a couple xmas lites for a few minutes after charging for a few min. I'm uncertain of the calibration of my v-meter, but it currently indicates 2.65v for these 2 cells. Depending upon the source, NiCads should max out at 1.45 to 1.65 v per cell.

Test 2: Pending- Ryobi drill batteries

I'm uncertain how to get a good read on the accuracy of my meter without a high-end meter to compare against. Suggestions?

Hopefully, I can find a proper 1 cell nicad charging device. 

Thoughts? concerns? insights?


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6 years ago

First thing I try is to measure the cell voltages.
Batteries that are much lower tha other are most likely dead.

You can charge the single cells with a normal battery charger by soldering the wires directly to the battery (in case they can't be inserted because of open design or size).
An electronic charger is good for this as it takes all the guessing out for you.
Mine shows the charging state for each cell, so if after a set time some cell still reads far below the other I found another one for the bin.

Everything else requires more or less complicated setups and a lot of time to monitor the performance of the cell.