Hi. Who could hint me what's going on with my battery NI-MH. I have a MD MZ-NF810 minidisck player. If I leave a battery inside of my MD it gets discharged, though if I charge the battery and take it out, then it is good to use. is it problem in batterry which i use for 2 years or something happened with MD. The battery works for a 8 hours. Thanks for all in advance.