Using non-rechargeable batteries on old HP calculators

[James P.G. Sterbenz]

This thread us is quite old, but appears to be the most recent in-depth discussion of voltage for HP battery packs. Having just received three of Bob Wolfson's battery adapters, and only owning 2 HP NiCd packs to share across my HP-35, HP-45, and HP-55, I wonder if there are any updates to this?

In http://www.hpmuseum.org/forum/thread-5570.html Bob suggests that it is safe to use 1.5V Alkaline cells. Do people still think it safe to run a classic on 4.5V? Did anyone ever manage to check against original schematics?

I've got some NiMH cells charging now, but would like to know if Alkalines or Li-ion cells are safe. I certainly don't want to damage my classics!