Macbook won't run on battery! HELP!

Hi,

I have a Macbook that won't run on the battery.

When it is plugged in, the battery charges and the computer runs fine, but as soon as the battery is plugged out, the Macbook will switch off. It is a 2009 Macbook A1181.

I tried a friends battery in my Mac and it still wouldn't work, and when I put mine into my friends Macbook, it worked perfectly so I don't think it is the battery.

Can anyone help?

remove all power from the computer and press and hold on the power button for 10sec. after 10sec put the power back to the computer and try again.

Taking the battery out and holding the power button for ten secconds works for macs too... I had to do that for our old (gag) HP laptop we had. Just asking.

Taking the battery out and holding the power button for ten seconds works on on macbooks, too?