c. Battery Pack Mods

Use any AA Batteries in vintage Calculators

Early calculators were power hogs. Consequently, they were equipped with NiCads that could be recharged in the calculator via its AC power converter.

In many calculators, the NiCads were built into the body, and not meant to be replaced. Since all rechargeables fade over time, these calculators were born to die. At best, repair required opening the calculator shell (not always easy), unsoldering the old batteries from their leads, and soldering new ones in their place.

In other cases, the batteries were in separate sealed packs that could be loaded into a compartment in the calculator. The vendor sold replacement packs and separate chargers, so you could always have a charged-up pack ready to go. New packs were available for many years after the calculators stopped being produced, but no longer.

Many collectors and others with dead NiCad packs figure out how to non-destructively open them up, remove the old NiCads, and seal them back up again with new rechargeables. This extends life to vintage calculators (yay!), but the old charging circuits don't deliver enough power to recharge today's high capacity batteries quickly. If you've got an uncharged pack, you may have to wait a day or two to charge it up!

I find that intolerable. I want to show off or use my calculators when I want to, and I can't manage to have charged-up packs always on hand. So I try to figure out how to make or remodel packs to use any AA batteries. This lets me use alkalines or whatever recharged batteries I have on hand. Since 15-minute-rechargeables are available these days, I'm never at a loss for calculator power.

Click the pictures below for more details.