LCD 128X64 ST7920 Powered By Lipo VS Power Supply Issue

OK guys!

This is weird issue that came up with some of my 128x64 ST7920 LCD's. I have the LCD 5v running off of the nano and the back light running off of the 3.3v on the nano. When I run the nano & LCD's off of my power supply or USB from the computer they work fine but when I hook them up to a 3s 12.4v lipo something changes. When first turning it on from the battery the lcd pixels will all light up white(blue background lcd). Then when I turn it off and back on it will be dim and I have to readjust the intensity control on the back. This seems really weird. Any ideas why display would do this?

Thanks,
Kevin

Anybody have an idea on this? Maybe someone that has used this type of lcd with batteries and especially lipo's?

Thanks,
Kevin