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Nate Martin · 12-01-2015, 03:02 AM

Greetings all,

I am looking for a HP41C rechargeable battery pack to disassemble for measurements and 3d modeling. Dead, broken, etc is fine so long as I can get measurements from the case (internal and external).

My intention is to make a LiPO battery for my 41's, modeled off the 82120A. These housing models would be uploaded to shapeways similar to the port covers and battery holders I did before.

PM me here with price or email zulu at zombiebunniez dot us

Thanks
Nate

TASP · 12-01-2015, 04:11 AM

If you're USA address, I'll send you one free.

It's in poor condition as a battery pack, but apparently fine for what you need.

Nate Martin · 12-01-2015, 04:15 AM

Thank-you, I got two offers pretty quick. Hopefully I will have some new models out for battery holders shortly.

TASP · 12-01-2015, 04:17 AM

K,

disregard PM

Nate Martin · 01-05-2016, 02:22 AM

Got the prototype back today for the nicad case based on the 41 rechargeable battery pack. I think it looks OK...but should have done it in black.

[Image: 41 recharge pack 1.jpg]

The LiPO pack is still a work in progress with also the first prototype today, looks like everything fits so now I just need to lay out the circuit.

quantalume · 01-05-2016, 06:28 AM

(01-05-2016 02:22 AM)Nate Martin Wrote: The LiPO pack is still a work in progress with also the first prototype today, looks like everything fits so now I just need to lay out the circuit.

Sounds interesting. Tell us more. I'm just about to rebuild one of those packs with 1/3 AAA NiMHs. Do you plan to have a DC-DC converter or run it straight from the LiPO? I thought about a LiPO, but the problem is that it doesn't have enough voltage to run the calc straight from the battery, and with a DC-DC converter, you need a separate power switch.

Sadsilence · 01-05-2016, 02:06 PM

Genius project.Really interested in the result. Maybe use oft 2S LiFePO4 pack makes DC converter obsolete. But then you do not have a capacity profit against 170 mAh NiMH 1/3 AAA cells.

Nate Martin · 01-27-2016, 06:03 AM

Completed rebuild of 41C NiCad case using new model, works ok and the model will be available on shapeways and thingiverse (http://www.thingiverse.com/thing:1296674). This allows use of legacy charging circuit with new batteries (1/3 AAA NiCad) and 3D printed case.

Now on to phase 2 the LiPo charging: series dischagre/ parallel charging in one case with a micro usb balance charging circuit.

damaltor · 01-27-2016, 06:47 AM

I wonder if i really am the only one with a rechargeable battery pack with a weird three-pin connector. All pictures i found so far have only two pins, including this one...

Massimo Gnerucci · (This post was last modified: 01-27-2016 08:48 AM by Massimo Gnerucci.)

(01-27-2016 06:47 AM)damaltor Wrote: I wonder if i really am the only one with a rechargeable battery pack with a weird three-pin connector. All pictures i found so far have only two pins, including this one...

You're not alone.
My oldest one has 3 pins.