HP Forum Archive 18

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HP41 Nicad pack and Batteries Message #1 Posted by Larry Fox on 28 July 2008, 12:57 p.m. Have there been any new developments since the thread in Archive #2 (year 2000) concerning availability of replacement batteries for rebuilding the HP82120A rechargeable battery pack for the HP-41C calculator line? I have such a pack and am looking for something with at least the original capacity (80-90 mAh?) to replace the original 1/3-AA (or 1/2-N). I have been in touch with Holman's of Nevada (702-222-1818), this date; and they have apparently lost any capacity they may have had for supplying or rebuilding these packs. Thanks, L. Fox

Re: HP41 Nicad pack and Batteries Message #2 Posted by Dan Grelinger on 28 July 2008, 1:37 p.m., in response to message #1 by Larry Fox From TOS: http://hp41.claughan.com/files/HP41Battery.pdf I've not tried it, I don't know if these batteries are still available. Rated capacity is 150maH. Dan

Re: HP41 Nicad pack and Batteries Message #3 Posted by PeterP on 28 July 2008, 3:37 p.m., in response to message #1 by Larry Fox alternatively you can use rechargeable Lithium batteries, that's what I do. There is a thread here somewhere where I mentioned a site where you can buy them and a recharger. There was some discussion about how well they work, etc so I can only speak from my own experience, which is very positive. Cheers Peter

Re: HP41 Nicad pack and Batteries Message #4 Posted by Dan Grelinger on 28 July 2008, 5:50 p.m., in response to message #3 by PeterP Peter, Are you sure you are using Lithium rechargeables? Could they be Ni-Mh? I bought some Ni-Mh rechargeble N-size cells through ebay, and they work pretty good, their charge capacity is very high. There is one problem, they are the 'flat-top' version, and the contact from the batteries is not as reliable as with the 'button-top' battery we are all used to. The Lithium rechargeables are not sold to consumers outside of a package containing sophisticated charging logic. Whereas Ni-Mh batteries can be charged much like Ni-Cds, and will stay safe, lithium rechargebles will explode, catch fire, and burn ferociously if over-charged. They are very light, with very high charge densities, so they have become almost universally the only laptop battery designed today, but even in those applications, if the charge logic faults, or if the battery package gets damaged, things can get pretty exciting if the battery overcharges! There have been recalls of millions of Lithium batteries over the past 5 years as a result, and many fires. Do your batteris have the button top, where the positive contact extends significantly from the battery top? Dan

Re: HP41 Nicad pack and Batteries Message #5 Posted by PeterP on 28 July 2008, 7:17 p.m., in response to message #4 by Dan Grelinger Dan, You are absolutely right, my mistake. I use NiMh batteries, what was I thinking! They have a normal button top head so I actually do not have a problem with the contacts. Thanks for the correction Cheers Peter

Re: HP41 Nicad pack and Batteries Message #6 Posted by Tim on 29 July 2008, 6:03 p.m., in response to message #5 by PeterP I purchase a sealed battery pack NI-MH 150mAH from Onlybatterypacks.com for $13.15. I had to modify the metal contact points for the battery as the link to fix a rechargable battery pack tells you.

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