HP Forum Archive 14

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Classics losing power... Message #1 Posted by Arnaud Amiel on 29 July 2004, 7:44 a.m. 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... Message #2 Posted by Emmanuel, France on 29 July 2004, 7:52 a.m., in response to message #1 by Arnaud Amiel 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... Message #3 Posted by Arnaud amiel on 29 July 2004, 9:32 a.m., in response to message #2 by Emmanuel, France 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... Message #4 Posted by Emmanuel, France on 29 July 2004, 11:00 a.m., in response to message #3 by Arnaud amiel You can use a bulb or a led. When light is weak, not far from 0V but not 0V!

Re: Classics losing power... Message #5 Posted by David Smith on 29 July 2004, 4:42 p.m., in response to message #3 by Arnaud amiel 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... Message #6 Posted by Jon on 30 July 2004, 12:11 p.m., in response to message #5 by David Smith 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... Message #7 Posted by Ronald on 30 July 2004, 4:48 p.m., in response to message #6 by Jon 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

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