HP Forum Archive 17

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Could I use AA alkaline batteries in a HP 35? Message #1 Posted by Miguel Toro on 14 Sept 2007, 3:57 p.m. I think of using NiMHs but I just wanted to know if it is safe for the calculator. Thanks, Miguel

Re: Could I use AA alkaline batteries in a HP 35? Message #2 Posted by Stefan Vorkoetter on 14 Sept 2007, 4:54 p.m., in response to message #1 by Miguel Toro Where would you put them?

Re: Could I use AA alkaline batteries in a HP 35? Message #3 Posted by Miguel Toro on 14 Sept 2007, 6:10 p.m., in response to message #2 by Stefan Vorkoetter The original Battery Pack was dead so I opened it (cuting by the seam, as the curator says) and arranged it so now I am able to put in and take out NiMh batteries easily. So now I want to try some alkalines if that is safe. Maybe I can show a picture of what I did (it is ugly but it works).

Re: Could I use AA alkaline batteries in a HP 35? Message #4 Posted by Stefan Vorkoetter on 14 Sept 2007, 10:43 p.m., in response to message #3 by Miguel Toro Oh, sorry. I thought you meant HP 35s. I wouldn't use alkalines in an HP-35 because their voltage is higher. Good NiMH batteries (like Sanyo Eneloops) will far outlast the original NiCds.

Re: Could I use AA alkaline batteries in a HP 35? Message #5 Posted by Miguel Toro on 15 Sept 2007, 7:47 a.m., in response to message #4 by Stefan Vorkoetter Ok. Thank you. So 4.5v can indeed damage the calculator. Regards, Miguel

Re: Could I use AA alkaline batteries in a HP 35? Message #6 Posted by Jeff O. on 15 Sept 2007, 7:54 p.m., in response to message #5 by Miguel Toro If I recall correctly*, a fully charged nicad puts out about 1.5 Volts. If you check the schematic of the classic charger, it indicates that the logic supply voltage is 4.2 Volts. Based on this information, it is hard to believe that 4.5 Volts would present any danger. However, better safe than sorry, so unless you have a strong need to use alkalines, why take the risk. It would also be bad if you happened to plug the charger into your calculator with alkalines installed. *-which I apparently do not, see below Edited: 15 Sept 2007, 9:04 p.m. after one or more responses were posted

Re: Could I use AA alkaline batteries in a HP 35? Message #7 Posted by Stefan Vorkoetter on 15 Sept 2007, 8:05 p.m., in response to message #6 by Jeff O. A fully charged NiCd puts out about 1.3V which quickly drops to 1.2V and then stays there for a long time. At 1.1V, it's almost dead. Stefan

Re: Could I use AA alkaline batteries in a HP 35? Message #8 Posted by JoeFrisco on 17 Sept 2007, 7:45 p.m., in response to message #6 by Jeff O. NiCads are 1.2 V. . . But I will accept the 1.3 V potential as offered by Stefan NiH are 1.2 V . . So you should be able to drop NiH cells for NiCad cells Alkaline Cells are 1.5 V. Edited: 17 Sept 2007, 7:47 p.m.

Re: Could I use AA alkaline batteries in a HP 35? Message #9 Posted by Mad Dog ebaycalcnut on 15 Sept 2007, 8:19 p.m., in response to message #1 by Miguel Toro No.

Re: Could I use AA alkaline batteries in a HP 35? Message #10 Posted by Miguel Toro on 15 Sept 2007, 10:21 p.m., in response to message #9 by Mad Dog ebaycalcnut Clear as water (as we say in Spanish)!. Thank you all for yours answers. Miguel

Re: Could I use AA alkaline batteries in a HP 35? Message #11 Posted by Chuck Sommer on 16 Sept 2007, 2:48 p.m., in response to message #1 by Miguel Toro I agree that using alkaline batteries is not a good idea. The first problem is that a really new alkaline battery can put out 1.6 volts or higher, but I suspect the calculator would be OK with that (4.8 volts). The more important problems are (as stated earlier) what if you put your charger to the calculator with the alkaline batteries, and if the alkaline batteries are left in the calculator long enough they will LEAK. For the last reason I would not try alkaline batteries as I can imagine putting them in and forgetting about it for a few years... and then being very unhappy. Chuck

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