82033A Peripheral batteries?


I have 5 toasted 82033A battery packs and no spares left. Has anyone figured out a way to open 'em up to replace the cells yet? I've done this with my HP-29C battery recently and brought it back to life, but these battery packs look a little more challenging and I'd like any advice before tackling it.

Alternatively, does anyone know where they can be rebuilt or where I can find fresh packs? My 41C peripherals are now idle until I can fix this.

Thanks. Cheers.


Easy as pie.

Just get a sharp knife and cut along the join. Take out the old cells and get some new ones (sub-C) made up into a pack and replace them.

I havn't even bothered to stick the two halves back together again, they hold together in the printer (or whatever) and make it easier to replace in another 10 to 20 years :-)

I wish I had 5 dead ones. I only have one that I've rebuilt, and it gets moved from the 97 to the printer, to the other printer, to the cassette drive, ...

you want to sell one?


Batteries Plus will rebuild for ~ $15


Seeing as how 98% of the time I use the printers and cassette drives while within reach of power, I'm wondering if the batteries can be replaced with large electrolitic (or even small tantalum) capacitors (if indeed they are used as part of the filtering or peak power handling). I have the manuals stashed in a box somewhere safe (where I can't find them currently ), and I'm not sure whether it is safe to use them without the batteries (or capacitors in their place). Has anyone tried any of these ideas?

I used to treat these batteries the way we were all trained to treat ni-cads (by running them down on full cycles mostly, without going to far to reverse cells etc.), always having a spare to swap in. Even then they had a dissappointing lifetime.

Assuming that the capacitor idea might not cut it, what about the NiMH cells? Would the normal charging wall-warts work with these and would they handle long periods of being plugged in when power was available (without exploding or something)?

Thanks for the advice.



The following is based on personal experience, so use it with caution...

Capacitors alone will not work. These will stabilize the voltage alright, but won't regulate it like a NiCd battery does, so your device will receive excess voltage. A simple circuit with a capacitor and a resistor (and perhaps a Zener, for more accurate control of the voltage) will, however, do the trick.

NiMH batteries seem to work fine. It takes longer to charge them, but of course they also last longer.

Keeping the machine plugged in all the time is a very bad idea regardless of what type of rechargeables you use. Since the charging circuit is not smart (i.e., it doesn't detect when the batteries are fully charged and doesn't turn off the charging current) your batteries will be overcharged, and although they won't necessarily explode, they will die a premature death.



The batteries died on both my Tape Drive and Printer. They must have batteries in them to run with the AC charger plugged in.

I took 5 Radio Shack AA 1.2 volt Ni-Cads, soldered them together and made a contact base from the Shack's Dual Mini Board #276-148.

The AA's fit perfectly within the battery compartment space although they are aligned perpendicular to the original batteries...

...and it works. The parts are easy to obtain and reasonably priced.

The downside is that my 41C sometimes shows some intermittent display problems which usually stabilizes. This might be due my using five 1.2V/1600mAh batteries.

Does anyone know how much mAh is enough? Radio Shack AA NiCads come rated at 1.25 V/600mAh or 850mAh, or 1.2V/1600mAh.

The AAA's rate at 1.25V/180mAh or 1.2V/550mAh.


I think it doesn't really matter what capacity batteries you use, that only affects the time that the batteries last before they need to be recharged.

However, I think that it is a mistake to use five NiCd cells instead of four. You're subjecting your devices to permanent overvoltage, which may explain the flickering display, and may cause other damage in the long run.



I tried four at first, but they seemed to die quickly even when plugged in to AC. 4 * 1.2 volts = 4.8 v and I think the HP battery is 6v.

But I think you are right. Maybe I should add a resistor.



I agree with Viktor, NiCds usually offer 1.25 V, and may even approach 1.3 V while just charged. (You can measure yours easily to see if this is the case).

Alkalines may be a little over 1.5 V when new, but a HP41 will run for months with a new set, and in average will be powered by 1.4 V on each cell.

So I would prefer four than five NiCd.

If you still think five is better, you may (at your own decision and risk) connect one standard silicon diode (1N4001, for instance) in series (forward biased) with the pack. The diode will in fact provide a voltage drop in the range of 0.65 V to 0.7 V.

The final voltage will be around 5.5 V, quite appropriate.

CAUTION: Of course, this suggestions are no guarantted to work, take them just as ideas on the matter.


You guys are right. I will measure the voltage and either cut out one cell or add the diode. Most of the time, my 41C is not plugged in to the HP-IL loop, so I am not too concerned, except when I do plug in. I was kind of amazed that the HP41 gets such a charge from the peripherals.

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