I tried to measure the rear light current and voltage and couldn't get anything to even register (on my garbage no-name digital meter to be fair). It should be 6v DC, right? Coming off an IQ-X front.
The power to the dynamo rear light is AC. It should be passed straight through the headlight when it’s switched on, so exactly what you’d find measuring at the dynamo.
Absolutely. Most of the rear lights draw around 30mA.