The Museum of HP Calculators

HP Forum Archive 09

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42s batteries
Message #1 Posted by Bob on 11 Jan 2003, 6:47 p.m.

Just found my old 42s and am wondering what everyone is using for batteries as the px675's (i think) do not seem to be available.

      
Re: 42s batteries
Message #2 Posted by R Lion on 11 Jan 2003, 7:01 p.m.,
in response to message #1 by Bob

LR44

            
Re: 42s batteries
Message #3 Posted by Glen Kilpatrick on 11 Jan 2003, 8:10 p.m.,
in response to message #2 by R Lion

My understanding is that Alkalines won't last as long as Silver Oxides, but that when they run out, the former will more gracefully decline, and you get a longer low-battery warning, whereas the latter will just about die on you. Others are welcome to give their impressions....

                  
Re: 42s batteries
Message #4 Posted by Katie Wasserman on 11 Jan 2003, 10:56 p.m.,
in response to message #3 by Glen Kilpatrick

The silver oxide ones (Everyday 357 or Maxell SR44) last many times longer in low drain applications like most HP calculators because they have extremely low self-discharge rates. The storage capacity of the silver oxide cells is about the same as the alkaline cells (A76 or LR44), around 160mah for each. But the self discharge rate makes a huge difference (unless you're running programs on the 42s 24 hours a day). The silver oxide cells cost about twice as much do but in calculators like the 15C and 12C they can last 20 years with nominal use while the alkaline cells will usually not last more than a year or so.

                        
Re: 42s batteries
Message #5 Posted by Bob on 12 Jan 2003, 12:25 p.m.,
in response to message #4 by Katie Wasserman

Wow! Thanks for all of the info.

Bob


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