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HP Forum Archive 09

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Alcaline Battery for vintage HP calculators ?
Message #1 Posted by Pyerre L. on 27 Nov 2002, 11:57 a.m.

Hello,

I just start collecting vintage HP calculators and get five of those : the HP-25, HP-34C, HP-33E, HP-34C and the 41C. All original rechargeable batteries have been long gone. Can I use normal Alcaline batteries to power them without problems ?

Many thanks, Pyerre

      
Re: Alcaline Battery for vintage HP calculators ?
Message #2 Posted by Emmanuel, France on 27 Nov 2002, 12:54 p.m.,
in response to message #1 by Pyerre L.

You can use 2 x 1.5V on HP-33E and HP-34C,
and 4 x 1.5V on HP-41C.
But please no alcaline battery on HP-25C, it's too fragile.
You can easily replace their batteries.
Use 2 x Cadnica N-450AA 1.2V 450mAh for instance
(HP-3X and HP-25C),
and 4 x Cadnica N-50AAA (HP-41C).
            
Re: Alcaline Battery for vintage HP calculators ?
Message #3 Posted by Pyerre L. on 27 Nov 2002, 1:33 p.m.,
in response to message #2 by Emmanuel, France

Hi, Many thanks for helps. Since you've mentionned about the HP-25C, I've verified and mine is the HP-25. I guess the alcaline batteries should work for this too ?

Thanks again, Pyerre

                  
Re: Alcaline Battery for vintage HP calculators ?
Message #4 Posted by Emmanuel, France on 27 Nov 2002, 4:33 p.m.,
in response to message #3 by Pyerre L.

Take care. Don't plug the adapter w/o battery inside! Don't use alcaline battery for this one too. Too fragile!

                        
Re: Alcaline Battery for vintage HP calculators ?
Message #5 Posted by Andrés C. Rodríguez (Argentina) on 28 Nov 2002, 7:30 a.m.,
in response to message #4 by Emmanuel, France

Many years ago, I used regular, alkaline batteries in my HP25 (not C) without problems. Of course, don't use alkalines and the AC Adapter/Recharger at the same time! It's just my experience, but be very cautious; a working 25 is a treasure you should protect.

Rebuilding the battery pack with new NiCd batteries is a good idea, or eventually with NiMH modern rechargeables.

In any of these cases, please recharge your batteries in an appropriate EXTERNAL charger. NiMH recharging requirements are different from NiCd. Even with NiCd, there is a very high chance that any bad contacts (oxide, corrossion, dirt, etc) or other circumstances, will cause excessive voltage from the AC adapter to be applied to very delicate (unreplaceable) parts of your calculator, killing it in a fraction of a second. I have not enough time for a detailed explanation now, but please avoid any use of the AC adapter in your valuable machines.

Also, with a modern, external charger, it will be much faster to recharge the batteries.

      
Re: Alcaline Battery for vintage HP calculators ?
Message #6 Posted by Pyerre L. on 28 Nov 2002, 9:28 a.m.,
in response to message #1 by Pyerre L.

Hi,

Many thanks for all of advices. The HP-25 came with the original battery pack (long died, of course) & its own AC adapter. No, I did not tried to use it with the calculator yet. I've built a small 2.5VDC power supply for the HP-25, test it and it works perfect. A real marvel. The HP-25 is my favorite (not the 25C). I don't know why.

Thanks, Pyerre

            
http://www.batteriesplus.com/
Message #7 Posted by Glen Kilpatrick on 28 Nov 2002, 10:42 a.m.,
in response to message #6 by Pyerre L.

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=254 (*Thanks*, Katie Wasserman) describes "battery surgery", but http://www.hpmuseum.org/repair.htm may have an alternative that lets someone else do the sweat, look for the "Having Someone Else Repair It" section.

There's a Batteries Plus in Sacramento, a friend with a 19C "Sting" and I should be trying out their "Battery pacs are sometimes repaired while you wait" stuff sometime in December. Note that NiCads are easy to get, spot welding may be harder (I haven't a clue, sorry), but the plastic that comprises the rest of the battery pack is most likely irreplaceable (thus our decision to leave this to the professionals).

                  
Re: http://www.batteriesplus.com/
Message #8 Posted by db(martinez,california) on 28 Nov 2002, 6:26 p.m.,
in response to message #7 by Glen Kilpatrick

just a general note: instead of spot welding i have had good luck with using a low heat solder that i got at radio shack. it comes in a squeeze tube and the paste contains its own flux. i have not overheated any batteries yet when using it.

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