41 Series Battery & Charger?

[BarryT]

Hi all,
. I have a question regarding the 41c Battery Pack. I've noticed some of the batteries have 2 prongs and some have 3. Does anyone know why there was a difference? Was one version more stable than the other? Do they both use the same charger? I would 'assume' they use different chargers, but perhaps the gap in the split plug of the 2 prong charger is large enough to straddle\bypass the middle prong?

. The connector on the 3 prong one resembles that of the Classic series, but on those, one of the outer prongs is power to the calculator, whereas the other is the charging circuit for the battery, and the center pin is the ground. Is this also true of the 41c's 3 prong battery pack, or is that middle prong just "there", and of no real use? Again I "assume" that it's there for a reason and not just for the moral support of the other two pins , but, I could be mistaken.

. Anyway... if I were to look for a battery pack to refurbish, should I look for a 2 or 3 prong? Is either more rare\valuable than the other? Not that I'm looking to pick one up to sell, I want it for my 41cv ... but it's always fun to have something that's rare when you can.

Thanks in advance.
. -=Barry

[rprosperi]

(01-25-2018 11:23 PM)BarryT Wrote:  Hi all,
. I have a question regarding the 41c Battery Pack. I've noticed some of the batteries have 2 prongs and some have 3. Does anyone know why there was a difference? Was one version more stable than the other? Do they both use the same charger? I would 'assume' they use different chargers, but perhaps the gap in the split plug of the 2 prong charger is large enough to straddle\bypass the middle prong?

. The connector on the 3 prong one resembles that of the Classic series, but on those, one of the outer prongs is power to the calculator, whereas the other is the charging circuit for the battery, and the center pin is the ground. Is this also true of the 41c's 3 prong battery pack, or is that middle prong just "there", and of no real use? Again I "assume" that it's there for a reason and not just for the moral support of the other two pins , but, I could be mistaken.

. Anyway... if I were to look for a battery pack to refurbish, should I look for a 2 or 3 prong? Is either more rare\valuable than the other? Not that I'm looking to pick one up to sell, I want it for my 41cv ... but it's always fun to have something that's rare when you can.

Thanks in advance.
. -=Barry

I don't have a link handy, however this discussion comes up every year or two, and has been thoroughly explored and explained. Suggest searching this Forum (Google works better than the built-in search tool - add "site:hpmuseum.org" to your google search probe). From memory, I'd say the last time this was discussed was about a year ago, which may help you to narrow the results.

[AndiGer]

... or e.g. here in this forum's archive
http://www.hpmuseum.org/cgi-sys/cgiwrap/...read=47494
Or here
http://www.hpmuseum.org/cgi-sys/cgiwrap/...?read=8645
Andi

[BarryT]

Very nice

Thanks to you both, Bob and Andi !!! Great information and links.

It sounds like picking up a 3 prong battery pack and dropping a Zener across the cells at rebuild time is the best way to go