HP Forums
Classics losing power... - Printable Version

+- HP Forums (https://archived.hpcalc.org/museumforum)
+-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html)
+--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html)
+--- Thread: Classics losing power... (/thread-61257.html)



Classics losing power... - Arnaud Amiel - 07-29-2004

I have recently rebuilt 2 battery packs for my 45.

I have discharged and recharged them only a couple of times since I rebuilt them.

Recently, when I turn on my 45, after a couple of seconds the low power indicator comes up and a few seconds later the leds turn off.

I measured voltage on the pack 3.75 V, I tried the same pack on an other 45 and a 55 and the same happens.

Did this already happen to anyone? Any idea of what the problem could be and how to fix it?

Thanks for your help

Arnaud


Re: Classics losing power... - Emmanuel, France - 07-29-2004

Dear Arnaud,
This problem occurs when you use low quality rechargeable batteries.
Before recharging them, you have to fully discharge them.
I used three Sanyo Cadnica N-600AA in my previous HP-67 and TI-59.
It was working well but not for a long time. Their value was 600mAh only.
Please test 1000mAh or more and let us know if it is better.
Kind regards from Normandy. Sincerely yours.

Edited: 29 July 2004, 7:54 a.m.


Re: Classics losing power... - Arnaud Amiel - 07-29-2004

Thanks for that. Any idea what should be the voltage of a fully discharged battery pack and how I can ensure it is discharged?

Thanks

Arnaud


Re: Classics losing power... - Emmanuel, France - 07-29-2004

You can use a bulb or a led. When light is weak, not far from 0V but not 0V!


Re: Classics losing power... - David Smith - 07-29-2004

I nicad cell is fully discharged at 1.0V per cell. Your problem may be due to a bad charger or problem in the intenal wiring chain though.


Re: Classics losing power... - Jon - 07-30-2004

I use NiMH cells. They are free of memory effect.
If you can charge them outside with an intelligent charger (should detect the fully charged condition) they will last a lot.
I built one charger, with the max712 chip, that charges these packs in one hour aprox. The result is just excellent. I can send the documentation of the charger.


Re: Classics losing power... - Ronald - 07-30-2004

Hi,

If you are sending the details of the charger I am intersted also. Could I ask you to send me the details to ?

Thank you