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Some time ago I recovered a 12v 1700mAH Ni-CD battery from an ancient Commodore Amiga black and white display laptop. The laptop works perfectly when powered by a 1.5a 12v adapter, but unfortunately the battery is in very bad shape.

Testing it with a multimeter, I got 0.011v from the battery. To verify the multimeter was in the correct mode, I tested a single zinc-chloride AA battery and got 1.652v.

Since the case is sealed and the voltage is so low it's pointless to test the cells. Is it possible to revive the battery?

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  • \$\begingroup\$ Extremely unlikely. NiCd is out of common applications for a reason. Some people claim that lead acid battery desulfators work on NiCd too, but I never saw any real evidence for that. \$\endgroup\$ – PlasmaHH Mar 19 '15 at 22:19
  • \$\begingroup\$ Just throw it in the bin appropriate for recycling this type of hardware. \$\endgroup\$ – Andy aka Mar 19 '15 at 23:07
  • \$\begingroup\$ Alternative option is to dismantle the battery and replace every cell with a brand new one of the same size and rating. This isn't viable with most new "intelligent" Li-Ion cells but if you can get into the battery it's an option here. \$\endgroup\$ – Brian Drummond Mar 20 '15 at 0:06
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Possibly. You first need to check each individual cell to see if it is shorted. Shorted NiCd cells are the most common failure when they are allowed to remain fully discharged for long periods of time.

If you do have shorted cells, do a Google search for "NiCd zapper" or "nicad zapper". This is a very simple apparatus consisting of a large, low-voltage capacitor and largish SCR. The idea is to burn open the dendrites causing the short inside the cells.

Then start putting charge into each cell individually. Anywhere from 100 to 250 mA is good to start. Continue charging until the terminal voltage gets above 1V.

Do each of the cells as I have described above. Once all the cells have some charge in them, put the entire battery pack on the charger and see what happens.

If you had an appropriate charger and enough time, my preference is to actually do a rejuvenate cycle on each individual cell. However, this process takes a lot of time and you have to do each cell individually. Even if you have a multi-cell charger, that means doing one cell at a time unless you split the battery pack apart into the individual cells.

I've had good luck recovering dead NiCd cells this way. One word of warning: the dendrites that cause shorts will begin to grow back if you allow the battery to discharge deeply. Always keep the cells charged.

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