Yep, needs to come straight off the main battery supply after the link and not through any circuitry.

One option is to run a few LEDs in series to drop the voltage. In Coyote, I used off the shelf 12V LEDs but was running the robot on 6S/22.2V. Wired up in series, they each see 11.1V which is plenty to illuminate them. Saves faffing about with resistors and such.