questions about calculator battery and memory


The battery life of my 42s seems to be shorter than normal. I kept the batteries in the battery compartment and seldom use the calculator. Ocassionaly (around a month) I would switch on the calculator and do some calculation or calculator test for several minutes. Last week, as usual, I switched on the calculator only to find out the battery was used up, and I remembered the battery lasted for only around 1.5 year. I also had my 32sII which I used much more frequently and the batteries had been used for more than 3 years without any sign of reaching the end of their life. I also remembered the days when I used my 42s extensively (especially lauching programs which required long time to run) the battery life would be rather short. So what's the real problem? Note: I didn't use the "fast" mode of the calculator.

Also last week, I switched on my 48G, and it displayed the "low battery" message. I switched the calculator off, took the old batteries out, only to find out that I didn't have any new ones. So I just let the calculator without its batteries, and installed the new ones three hours later. Expecting the memory to have been cleared, lo and behold, no memory was lost! Is it normal?


I've had the batteries out of my 41CX for up to 6 hours with no memory loss, and it seems like my 29C will go for a couple of hours with no memory loss as well. The CMOS circiutry draws very little current, and/or the capacitors are big, I guess.

Best regards, Hal


I have seen 41CX's hold their memory for a month without batteries. Most HP41CV's seem to be able to go at least a week.


You might want to measure the voltage on each of the three button cells in the 42s. You'll probally find that two test good and one tests very low. I've had the experience of buying three new batteries only to find out that the last one had been on the store shelf for many years. The store clerk had just kept adding new batteries to the front of the rack and the older batteries would stay around for a long time until a customer finally purchased a large enough quantity to buy from the rear of the rack.

I'd just throw three new cells in and you'll probally find they'll last a long time just like you remember they used to.

I make a point of testing each new battery before I install then just to make sure I don't install an obivious bad or low battery.


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