Originally Posted by tom @ eas
While it should be ok, it's better to be safe than sorry. We use a power supply whenever possible, it's not worth the risk if it's easily accessible.
Proper precautions have to be taken during coding, we even require customers to turn off Bluetooth on their phones in case a call comes in during the coding process.
I'll bet the local shop was just going to let the engine idle while coding the lights to the car. Does that sound safe?