Electronics > Beginners
Solder directly to NiCds?
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CarsonReidDavis:
@David Hess

Unfortunately, there are 4 batteries soldered, two on the negative terminal and two on the positive terminal. The one in the photo looks as if it has only been soldered once, but that is because I had to desolder the negative wire to remove a faulty inline fuse.
james_s:

--- Quote from: CarsonReidDavis on June 16, 2018, 01:53:32 pm ---@james_s

Do you have any information on how you built your unit and what the cost was? I might be interested in building one for myself.

--- End quote ---

I think I spent about $100, most of which was for ~1F worth of 22,000uF capacitors. There's not much to it, a variable power supply based around an LM317, relying on the short circuit protection to limit the current, lazy but works fine. I used the biggest stud mount SCR I could find for a few dollars on ebay to dump the capacitor bank into the welding probes. For the probe assembly I used pieces of #6 solid copper wire sharpened to a point and lengths of 2AWG car stereo power cable to the box.

Since you might be tempted to try, I'll mention that prior to this design, I tried using one of those big 1F car stereo capacitors and it worked for about 10 shots then failed.
Audioguru:
I stopped using AA size Ni-Cad batteries about 20 years ago when Ni-MH cells were introduced. I can't find anywhere today that still sells old fashioned Ni-Cads but modern Ni-MH cells are sold everywhere.
Ni-MH cells have a much higher capacity, hold a charge for 1 year instead of just a month or two and do not have the Ni-Cad "memory" problem.
Even my cheap solar garden lights use Ni-MH cells. They used Ni-Cads years ago.
Ni-Cad packs might still be used in high current RC toy cars but your 'scope does not use a high current. 
james_s:
NiCds are still occasionally used for replacing cells in devices designed for NiCd. In many cases a charger designed for NiCd will work fine for charging NiMH but this is not always the case.
mikerj:

--- Quote from: Audioguru on June 16, 2018, 05:16:28 pm ---Ni-MH cells have a much higher capacity, hold a charge for 1 year instead of just a month or two

--- End quote ---

This is only true for the low self-discharge types such as Eneloop.  Standard high capacity NiMH can have very high levels of self discharge.
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