when my computer goes in sleep mode it turns itself off
When I put my Imac into sleep mode, after a while it turns itself off. Soem one told me it may be the battery? Can you confirm?
iMac G5 (17-inch), Mac OS X (10.5.8)
The only way to confirm that the battery is still good, is to remove it and check it with a voltmeter. Or just replace it, since it's not very expensive (and commonly available). It looks like this
http://eshop.macsales.com/item/Newer%20Technology/CR2032/
But before you do that, the procedure to reset SMU (power management) may fix the problem. First, reset the PRAM, if you have not already
http://support.apple.com/kb/HT1379
and if that does not help, reset SMU (follow procedure precisely)
http://support.apple.com/kb/HT1767
When you connect it to back to power, everything else should be disconnected. Start it up with nothing but the power cord connected, then add only a standard USB keyboard and mouse. Use it that way for a while to see if the problem still occurs. If it does not, add USB and FireWire peripherals one at a time to see if the problem comes back.