Acer 8204 Battery Issue If you wanna call it that

Ive recently purchased a new mobo for my Acer 8204 it runs great on Power Supply but ive noticed i dont get much on battery ill quickly explain...

1st time I loaded up Windows I get to the Windows Boot Screen and the laptop switches itself off (this is only with the battery in. The battery which is at full charge).

2nd time i loaded it up in the bios, and kept it at the bios for about 10mins, this is still with just the battery in, no power supply. And its still at bios..

So obviously the battery is giving power to the laptop, its just not willing to run Windows.

to add to this: Ive just installed my hard drive with the OS from my previous defunct board, do you think the issue could be something as simple as, a reinstallation of the Operating System. As Ive just ran the hard drive of my previous install with the old board do you think that could be a major issue..

On Power supply the laptop runs perfectly fine its just at times i am at college no power sockets are available and id rather run off battery, ive got 2 working batteries.

Please help Acer Gods!!!!!!

 

anyone peas help