Solved- shutdown problem with NiMH battery on Sandisk m240

Using a several -year old NiMH battery, I had a problem when trying to turn on the player. After a few seconds, it would shut down ( with no message on screen). I solved the problem by adding a a capacitor in parallel with the battery. The capacitor I used has a value of about 600uf at 10volts. Evidently, during the turn on process, there is a large current spike that overwhelms the battery. Adding a capacitor helps to keep the voltage stable during this high current draw, which allows the mp3 player to turn on properly.

Message Edited by jimdagys on 08-21-2009 01:53 AM

Your information about this concern is highly appreciated but in laymans term how does it happen? my apology because I am not to technically savvy. :wink:

I am sorry, I can’t explain any better than I already did. One thing, I have never opened my mp3 player. I tried once, and gave up (I realize there are directions on this website on how to open up the player). Therefore, the capacitor (that I added) is soldered directly to the battery and consequently, this does not allow me to install the battery cover because of the space that the capacitor occupies. The capacitor is small (smaller than medicine capsule for curing colds).

Unrelated to this topic, I have also soldered and glued several other tiny things directly to the battery that allow me to charge the battery.

  1. charge jack - I can charge the battery with or without removing it from the mp3 player. I can charge the battery while the mp3 player is turned on or off. If desired, I can remove the battery from the mp3 player and charge the battery.

  2. current limiting resistor - because my AC charger is used to charge other things ( 1,2 or 3 batteries in series), it was necessary to add a current limiting resistor. This way I don’t have to use different chargers. One charger will charge several different things

  3. Diode stack voltage limiter- Because the charger I use is a very cheap lightweight 120/220volt type, it produces voltage spikes which could ruin the mp3 player. Therefore I added 3 diodes in series that will limit any possible voltage spike to less than 2.2 volts (.73V per diode X 3).

Message Edited by jimdagys on 08-20-2009 05:55 PM

Message Edited by jimdagys on 08-20-2009 06:00 PM

wow…hands up for you man, well thanks for the information, i hope some with same issue will have the guts to do this and again thanks for the information I will surely check this post every now and then to try it. :wink: