Ni cads for FLUKE 8600a

[rickjl]

I have an old FLUKE 8600a DMM.

The way the power supply works is there is a 5 uF cap in series with the AC primary to a transformer and the secondary has a half wave bridge that charges 4 D Cell nicads hooked in series. I assume these spikes are something like a trickle charger. This battery provides the 5 volt logic supply and then the 5 volts drives a self resonant switcher that provides +/- 15.

Two of the 13 year old ni cads are shorted (does interesting things to the operation). Sounds simple, so I need 4 D Cell ni-cads with solder tabs. I find D Cell ni cads are considered obsolete and are no longer available.

So I look and they have Ni MH batteries with the solder tabs now ($19 each???). I figure all is well until I look at the product description in Digi-Key it says "FLAT TRICKLE CHARGE CANNOT BE USED".

Does anyone have any ideas or better yet a source for D Cell ni cads with solder tabs welded on?

[Netlist]

Why not solder the tabs or some wire to the batteries yourself?
D cells are pretty big and with a good soldering iron I wouldn't be afraid to overheat them. Assuming you can get normal NiCad D cells of course.

/Hugo

[mrmodemhead]

Batteryspace.com has them.

[dangus]

Have you tried "zapping" the shorted NiCads?
My technique:
Get a car battery or some similar 12V source.

Attach wires to the 1.2V nicad, and put the nicad behind some kind of safety barrier. Connect 12V to the nicad through a hundred ohm resistor (to limit it to a normal charging current).
Monitor the voltage across the nicad with a (wait for it) voltmeter.
If the cell is shorted, voltage will be very low.

Now the fun part: take a length of say 18 gauge wire (to provide a little resistance), and very briefly (just brush the end of the wire) short across that dropping resistor. Watch the voltmeter. If it shows that the nicad is beginning to take a charge (steadily rising voltage), leave it to charge (or use a proper charger). If not, zap it again.

This worked on a couple of old Fluke bench meters I picked up surplus. I don't suppose the batteries have full capacity, but the meters are usable.

[rickjl]

Originally posted by dangus
Have you tried "zapping" the shorted NiCads?
My technique:
Get a car battery or some similar 12V source.

Forgot about that trick, I'll give it a try. The batteries are 13 years old.

This is also a surplus find.