Steppers cause lcd to flash

I was fiddling around with the extruder and I noticed that when I spun the extruder stepper the lcd backlight flashed on. Then I went on the move the y axis and again the backlight flashed, finally I tried the x and it did not flash. Is it bad that current from the steppers is somehow flowing back into the lcd backlight power supply? The steppers are wired through the drivers normally ( pins next to the drivers). I'm using an lcd kit that has a mini little "shield" ie it's own small pcb that plugs into the RAMPS

It is normal. Turning the motor generates an AC voltage. The drives have clamping diodes that clamp the back EMF voltage to the supply rails, so in this case they form a bridge rectifier that puts DC voltage onto the 12V rail.

It shouldn't cause a problem provided that the brown out fuses of the atmega are configured correctly.

---

[www.hydraraptor.blogspot.com]