Display is very dark when powered on only with battery

I have an Inspiron 15R N5110 and if I boot up with just the battery the display will be very dark. Too dark to see clearly and the brightness cannot be adjusted.

So unless I connect the AC adapter to the system before booting up the display does not work properly. After it has booted up I can unplug the AC adapter and it works fine.

The system board, display assembly, display panel, VGA/power board  and AC adapter have all been replaced.

All hardware diagnostic scans have been run on this laptop and no issues have been found. The BIOS and all drivers and files are up to date.

Any help with this issue would be appreciated.