HP41 battery holder, are there any CAD drawings?

[Ian Phillips]

I am fortunate enough to have two spare 41CVs and would like to make use of them but I do not have the battery holders.

Being a calculator user rather than a collector I am not bothered about originality or cosmetics so I am thinking about making some battery holders by fabricating/milling or even by SLA techniques.

As I have got one good holder I could create my own drawings but thought that if any drawings did exist (I have searched the archives) then it would make my task easier, hence my request.

Out of interest, I bought my first HP41c in the Singapore duty free shop in 1979 and it cost $670 dollars.

Ian

[Gerson W. Barbosa]

Jean-Michel made a 3D model of the HP-41 some years ago. I think it included the battery compartment, but I cannot find it right now.

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv017.cgi?read=117508

Gerson.

[Mark Hardman]

For fabrication of small lot plastic parts, Shapeways http://www.shapeways.com does miracles in the 3D printing arena.

In addition to the holder itself, you would need to source the paired battery terminal springs. Anyone have a source? I have several used battery holders with springs that have completely corroded. These could be put back in service if I could just find replacements for the springs.

Mark Hardman

[NateB]

Someone is already selling an aftermarket holder on TAS. It is not identical, but close. I think they are ~$35. I don't know if you could produce your own for less.

[Ian Phillips]

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Someone is already selling an aftermarket holder on TAS. It is not identical, but close. I think they are ~$35. I don't know if you could produce your own for less.

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Making it myself would be totally uneconomic, but it would give the satisfaction of having done it. Machining Acetal or PVC is very easy and I am sure I could fabricate the sprung contacts out of phosphor bronze or nickel silver sheet.

When I mentioned the SLA though it was because someone I know has a friend that knows someone that has the equipment as his place of work. certain favours might be exchanged without recourse to real money!

Ian P

[Marcus von Cube, Germany]

Ian, have you considered making a holder for a 6V lithium battery? The cell will work forever in a 41C. Maybe you'll find some buyers for such a holder.

[Ian Phillips]

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Ian, have you considered making a holder for a 6V lithium battery? The cell will work forever in a 41C. Maybe you'll find some buyers for such a holder.

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Its a good idea. I was going to use 'N' cells just because of simplicity and also I was not considering doing these on a commercial basis.

I got over 4 years usage out of my last set of alkaline cells (I use it frequently but only for short periods). With Lithium cells I might get 10 years!

Ian P

[Frido Bohn]

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With Lithium cells I might get 10 years!

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Well, this may be true for a 41 in its basic configuration. If you look at the old problem with the power consumption of the magnetic card reader or at the newer extensions (41CL and some modules) which drain batteries very fast, a rechargeable solution based on lithium cells would be very much appreciated.

That of course applies for the guys who want their 41s primarily running and not just in a showcase ;-)

[Dieter]

A rechargeable solution based on Li-Ion batteries would provide 7,2 Volts (two cells) nominally, right after a complete charge even 8 Volts and more. So it will not fit without additional electronics. This point has been discussed here every once in a while. ;-) Otherwise a commonly used camera battery would be a nice solution.

On the other hand, single-use Lithium-batteries with their 6 or 6,2 Volts should be fine. A common 2CR5, as found in any photo store, provides about 1500 mAh, i.e. almost twice the capacity of a regular N-size cell.

Dieter

[Ian Phillips]

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Well, this may be true for a 41 in its basic configuration. If you look at the old problem with the power consumption of the magnetic card reader or at the newer extensions (41CL and some modules) which drain batteries very fast, a rechargeable solution based on lithium cells would be very much appreciated.

That of course applies for the guys who want their 41s primarily running and not just in a showcase ;-)

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The 4 year battery life I mentioned earlier was for a 41cv with no peripherals (just Machine and Thermal Pacs).

In fact I only took the cells out when I got the 'low batt' warning when I tried the cardreader for the first time in about 5 years. I might put the cells back in now that I have fixed the gummy roller just out of curiosity.

Ian Hillips