Classics losing power...


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



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.


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




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


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.


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.



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

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