Craftsman NiCd Battery Packs

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
I am trying to rehabilitate some old Craftsman battery packs for 19.2 V and 14.4 V tools. They all contain NiCd, SubC cells. My chargers are only for NiCd. The oldest packs have almost no built-in protection. The newer ones have two devices. One is a thermal fuse/switch labeled 115°C that is taped to an outside battery. This device was stuck in the center of the pack between cells and is in the negative lead of the charging supply. It is not a diode so far as I can tell. It has a resistance of about 13 K in either direction. Diode function reads open in both directions.

upload_2018-12-23_15-1-50.png

As it turns out, 19.2 V packs are available after market for less than the cost of new cells, and I bought a pair. The prices for replacement 14.4V packs NiMH are about twice the cost of the 19.2 V ones. The NiCd versions of the 14.4 V packs are even more expensive.

Any ideas on what that device is?

Thanks, John
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
Here is the circuit as I see it. Maybe that will help. I looked for zener's with built in resistors and found none, but since it is apparently an unsophisticated charger for multiple battery voltages , that is still my best guess, except the 13K resistance is a bummer (its a 1-hour charger for 2200 mAh batteries) as are the diode readings. So, I am at a loss.
upload_2018-12-23_17-20-35.png
 

oz93666

Joined Sep 7, 2010
737
NiCd is stone age battery tech... convert over to Li-ion , get three and a half times more storage for the same weight and price ...and a longer life

 

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
Thank you for the advice. I am aware of those battery types and also use LiFe(PO4) and NiZn. I have 4 cordless tools that I do not use all that frequently, 4 chargers, and 3 locations where I keep chargers. Three of the tools are 19.2V and one is 14.4V. The 14.4V tool is a 1/4" impact driver that I almost never use. I don't like to use an impact tool when a hand wrench will suffice.

From a value-to-me perspective, I decided to stay with NiCd for the time being. A pair of replacement batteries for the 19.2V tools was about $30. I have a battery tab welder and will probably just build a pack for the 14.4V tool, if I decide to keep it. I suspect the cordless tool market will eventually settle on just one or two types.

As for that mystery part, I found a couple of comments that called it a "thyristor" with no further description. I suspect it is one of the versions without a gate, such as a BOD.
 

shortbus

Joined Sep 30, 2009
8,482
I have a battery tab welder and will probably just build a pack for the 14.4V tool, if I decide to keep it
The 14.4 volt tool would probably be very happy and live on a 19.2 battery, if the 19.2 battery 'stalk' (the part that plugs into the tool) will fit in the 14.4 tool.
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
I have tried it with the "stalk" cover removed, and it worked fine. It did have pep. (The stalks on the 19.2 V have a ridged key on them that prevents insertion in the 14.4V tool.) Of course, the 19.2v packs have 4 more cells and the pack is longer. I considered clipping those cells off (3 off the long end and one off the short end) and jumpering to fit my 14.4 battery case. The series connections are different, so that scheme requires a jumper wire on the long end. The short end can just be done with a new welded tab. I am concerned about the function of the "diode" thing. If it is something with a set breakdown voltage, that may be related to the charge voltage. Of course, I could also switch over "diodes."

It's a toss up between cheap and how much hacking I want to do. The bummer is that 15 Tenergy cells cost $34.50 and a two pack of 19.2V NiCd's costs $32.58. I previously bought that pair of 19.2 V packs. They seem to work and have held a charge for the past week. I don't know how long that will last, though. The Tenergy are maybe better cells.
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
I got a working 14.4 V pack by removing 4 cells from a marginal 19.2V pack and re-positioning the "stem." The stem fits, but needs to be re-positioned backward about 1/2". I just cut the existing connector bar and spliced in a piece of nickel tab material that I have. Not pretty, but it works.

Those new packs I bought for 19.2V are pretty cheaply made on the inside. If they hold up, I might buy another pair just for the batteries. If not, making a new pack from bare cells is probably easier, but a little more expensive.

BTW, the equivalent device in the new packs looks much more like a very cheap NTC versus the tryristor mentioned by others. I will test its resistance vs. temperature later.
 

beatsal

Joined Jan 21, 2018
213
Thank you for the advice. I am aware of those battery types and also use LiFe(PO4) and NiZn. I have 4 cordless tools that I do not use all that frequently, 4 chargers, and 3 locations where I keep chargers. Three of the tools are 19.2V and one is 14.4V. The 14.4V tool is a 1/4" impact driver that I almost never use. I don't like to use an impact tool when a hand wrench will suffice.

From a value-to-me perspective, I decided to stay with NiCd for the time being. A pair of replacement batteries for the 19.2V tools was about $30. I have a battery tab welder and will probably just build a pack for the 14.4V tool, if I decide to keep it. I suspect the cordless tool market will eventually settle on just one or two types.

As for that mystery part, I found a couple of comments that called it a "thyristor" with no further description. I suspect it is one of the versions without a gate, such as a BOD.
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
11,088
Those 19.2V packs I bought have held up so far. Multiple recharging and hold a charge quite well. Can't comment on the current status for buying any of them.
 
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