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I found my dad's old HP45 calculator, it works on AC power but of course the battery pack is long dead. I modified it to use a cordless phone NiCd pack, however I am unhappy with this, as the pack fits quite tightly and puts some pressure on the battery cover.

I want to take apart the original battery pack and replace the cells in it (with NiCds), I am however having a hard time cracking the original pack open. Does anyone have any experience with the disassembly of the original HP battery pack?


You just need to work at the seem. Use the widest, thinnest blade you have. It is fused together, but will usually pop apart. Alternatively you may need to cut through where the fused tabs are.

Working along the longer sides I was easily able to pop the seams, however it still didn't come apart. Is it also fused along the shorter sides? I have worked at these with a blade, no luck. I am considering just cutting the thing. I never expected this to be so challenging!

It's not connected along the longer sides, just the ends. Packs differ greatly in how difficult they are to take apart. In the worst case you need to cut almost all the way through.

"Packs differ greatly in how difficult they are to take apart."

I had to cut it, after inspecting it opened up, there was no other way, each side had 3 little tabs that were glued/fused to the other half. I soldered in 3 AA NiCds and closed everything up. Works nicely and fits well.

Now I will be the envy of my lab :).

Thanks Katie and Aj for the info.

Edited: 11 May 2011, 11:46 p.m.