Battery problem

[DYGIT]

Have had Mogul for a few weeks - the first week, the batery seemed fine and would go days without a recharge but now it is only holding a charge for a day or so....am not running wifi, bluetooth or anything and very few calls - anyone else having this problem? I did buy a car charger and backup ac charger on web for cheap - info on the charging rates on ac charger are same as factory one, but is it possible that they are not shutting off when finished charging and overloading battery? Or will the phone in effect shut off the charge from coming thru if battery is fully charged?