K5IP said:If you pluged into your trailer when the trailer battery was well discharged, the charge rate from your truck system can exceed 20A, especailly if the truck is running. This can be prevented by plugging in with the engine off and allowing the charge between batteries to stabalize for a few minutes before starting the engine. I monitor the carge rate on my trailer with a built in shunt/ammeter system and high initial peak surges are not uncomon.
Carry extra fuses.
Rog