I really need help. I have a 99 Dodge Diesel with a factory installed hitch and 7 pin connector for a trailer plug in. The wire that charges my trailer batteries in this 7 pin connector is no larger than #14. If my batteries in the trailer are very low and I turn on my Frig to DC 12 volt and start the vehicle it seems like the the amperage requirements for my camper would be very high. The frig is rated for 12.5 amps at 12 volts and if the batteries in the Trailer are low there would be a whole bunch of amps required to recharge. Why doesn't this big amperage requirement burn up the vehicle wire.

 

Battery isolator.

 

Travist: What is a battery isolator and how will it help me?