HP Forum Archive 14

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HP-31E Battery Pak Message #1 Posted by Trent Moseley on 26 Dec 2003, 4:53 p.m. Dear Forum, One of my sons, knowing of my interest in old HP calcs, gave back to me for Christmas the 31E that I had given him in 1981. It is in excellent condition with Owners Manual, AC adaptor, but minus the battery pak. My son says it works fine with just the adaptor. But I remember reading in the Forum as to the 25C, never to use the calc on the adaptor without the pak in place. Questions: Is this true for the 31E and can I somehow rig up a pak using two AA rechargable batteries? tm

Re: HP-31E Battery Pak Message #2 Posted by Randy Sloyer on 26 Dec 2003, 5:05 p.m., in response to message #1 by Trent Moseley Two AA ni-cad/ni-mh cells and a bit of foil opposite the connector to complete the connection will do in a pinch. Long-term it's best to get two cells with a strap welded on to make the connection. Don't have the cells glued together, best to have them loose so they can make proper contact. It's the same arangement for Woodstock batteries.

Re: HP-31E Battery Pak Message #3 Posted by Katie on 26 Dec 2003, 10:13 p.m., in response to message #2 by Randy Sloyer There's next to nothing to do to make a 3x (Spice) series battery pack from scratch. Just order part number P253-F021 from Digikey http://www.digikey.com and put a piece of tape across the gap (between the cells) on one side of the pack to prevent you from inserting it into the calculator the wrong way. Take a look at these pictures to see the right orientation: http://www.hpmuseum.org/batts/batt30.jpg http://www.hpmuseum.org/batts/bc30.jpg

Re: HP-31E Battery Pak Message #4 Posted by David Smith on 29 Dec 2003, 1:22 p.m., in response to message #2 by Randy Sloyer The woodstock machines need the batteries to not be glued together for proper contact. The spice machines have those spring contacts in the battery compartment that work best with cells that are glued together.

Re: HP-31E Battery Pak Message #5 Posted by Emmanuel, France on 27 Dec 2003, 3:43 a.m., in response to message #1 by Trent Moseley Dear Trent, It also works without adapter. Just use two 1.5V batteries instead of rechargeable 1.28V batteries. Yours.

Re: HP-31E Battery Pak Message #6 Posted by Trent Moseley on 27 Dec 2003, 12:49 p.m., in response to message #5 by Emmanuel, France Thank you all so much. It works! tm

Re: HP-31E Battery Pak Message #7 Posted by Emmanuel, France on 27 Dec 2003, 2:34 p.m., in response to message #6 by Trent Moseley Don't forget that you cannot use 1.5V batteries with charger!!!

Re: HP-31E Battery Pak Message #8 Posted by Trent Moseley on 27 Dec 2003, 11:25 p.m., in response to message #7 by Emmanuel, France Thank you Emmanuel. I'm using 1.2V Nickel-Metal Hydride. tm

Re: HP-31E Battery Pak Message #9 Posted by db(martinez,california) on 29 Dec 2003, 10:55 a.m., in response to message #8 by Trent Moseley I've used loose NIMHs too and it works great. I've also used alkaline cells and since i was not sure if the calc wanted a full 1.5v i fed it slightly used batteries.

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