L400 only boots with AC but then works with battery

nextmike,

Thank you for using the Dell Community Forum.

Please check the charge directly on the battery, using the button and lights on the back of the battery.  If any of the lights flash, or if alternate lights come on, then the battery needs to be replaced.

Batteries are warranted for one year from system purchase date.  If your system is less than one year old, then you can contact Technical Support for a replacement.

Please run the Dell Diagnostics.  There may also be a problem with the motherboard.

battery is fully charged but I still experience the same problem.

Has a solution been found for this problem? Im having the same thing happen with my L400. It boots fine when plugged in to AC power and will run on the battery once booted.

Ive recently found it will boot without being plugged in if I take out the battery and then put it right back in.