Acer Aspire One D257 Battery Isuue

Hello,

i have issue with my AOD257, initially it was not charging battery, updated the bios, now I can charge the? battery but the battery time is not realistic, sometime it shows 7hrs remaining with 70% battery and sometime with 100% battery shows 4hrs remaining,
it keeps changing Randomly.

and occasionally won't boot up after shutdown, only low battery light flashes & Silence, I have to take out batter and then put it back again, and then it will run smoothly, can any 1 help??