Hello, I was reading a previous thread that is now closed. What I'm curious about is a simple wiring schematic. I want to charge a battery on my trailer while it's hooked to the truck from the trailer 7 pin rv connection. The rv connection has a 12v hot all the time wire that I could use to trickle charge my winch batteries while towing. The issue is the feed wire is 16ga and fused at 15amps. To avoid running heavy wires I read where you can simply install an incandescent light bulb to limit the amps. My question is- I assume just wire it in series in the positive wire? If that works it's great the bulb will show that I have juice plus charge batts and not overload wires when trailer batts are low from either use without charge and or sitting extended period of time. Here is the original post I was reading: Charging 12V from 12V, but limiting the current https://www.physicsforums.com/threads/charging-12v-from-12v-but-limiting-the-current.364343/ Thank you in advance.