Hello, I have a Dell Precision M70 laptop. My question is about my battery. The battery is brand new and it holds a 3 hour charge for quite a while. My question is that when I shutdown my system and then try to start it up using the battery and no AC power it won't turn on. If I plug the AC power cord in with power, then the laptop will boot up. While in windows I can unplug the AC cord and run on the battery which has a full 3 hour charge. Should I take the battery out and use an eraser on the contact points? Or is there some setting I have overlooked? Or should I shutdown the laptop with the AC cord unplugged to boot up with the battery? I am lost at this point because the battery is good. Any advice would be appreciated. Thank you, Peter

If the battery is kinda old, I would suspect that it's not capable of putting out the amount of current that it used to. Startup draws much more current then normal running.

Thanks for your help.

Follow up - The motherboard was going bad. I bought a new Dell Vostro.