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Will it damage a classic (HP45) to power it from alkaline batteries? I have fashioned a battery holder for a 45 I received by skeletonizing a standard 3 cell (AA) battery holder. It powers up and works fine, but I am concerned that the higher voltage might damage the calc. I am considering buying some AA nicads or NiMh batteries and a charger. I already have a 25 that has been modified to run on AA alkalines and has done so for years. I also have a 34c without a pack. It works with alkalines also, but will they damage it?

Recieved wisdom says dont do this on Classics or Woodstocks, anything else is fair game. Classic electronics are fragile enough without any help. Remember that modern hi capacity ni-cads will run machines for almost double the length of time than the original pack did.

Good NiCds to use are Sanyo 1100AAU. They are the same size as AA cells, and are 1100mAh. At the time many of the classics came out, the best AA sized NiCds could do about 475mAh (if that). So we're talking 2.3 times the capacity.


Hello, by accident I discovered that there is a classic NiCd-Batterypack available from HP today. The HP-Part# is 1420-0272 it works fine for my classic calculators.

Andreas Stockburger

Andreas, Where did you locate the battery pack? I went to the HP Web site, then searched for this part number and I could not find it. Did you order over the phone directly from HP. Please give more information. Thanks. Jerry

I used the HP parts phone number found in this forum, and the part number that Andreas provided, and ordered 3 of these, along with a battery door for my HP-28S (which masquarades as an HP-19B part, also found in this forum). I received them today, and they are the batteries, connected physically and electrically together properly, but without the plastic case around the pac. This leaves them loose in the calculator, and provides a possibility of reversing them and providing negative polarity to the calculator. I cut out some cardboard and taped it to the ends of this battery pack to keep it snug. It works well in my HP-67 and HP-75D. They cost $21.00 plus tax.