Aux power limit

[Bob 5th Wheel]

On the 2021 Silverado 2500 HD with trailing package and heavy duty alternator - what is the max watts or amps supplied to pin 4 of the trailing plug? I tested it and it seems "Hot" all the time unlike the 115v plugs in the cargo bed. 

[sgordon99]

i’m pretty sure that’s exactly what it is, I have a pigtail on my transfer tank so if it’s on a trailer I can just plug it into the 7 pin. 

[Another JR]

My truck (gas) has dual batteries and one 220 amp alternator.  It has a 30 amp fuse at the aux battery that supplies pin 4 on the trailer connections, and that pin is always hot. 

[Bob 5th Wheel]

On 4/24/2021 at 11:13 AM, Another JR said:

My truck (gas) has dual batteries and one 220 amp alternator.  It has a 30 amp fuse at the aux battery that supplies pin 4 on the trailer connections, and that pin is always hot. 

Why dual batteries?

[Another JR]

It allows you to have an isolated battery for accessory loads when the truck is not running without running down your starting battery.  It charges when the truck is running.  People run various things off of them, such as a winch.  I bought the option thinking I may use it to power a refrigerator/freezer in the back seat and an air compressor for adding air to the tires after airing down.  It was one of those options that's cheap to order with the truck but more expensive to add later.  It cost about $40 more than a battery alone would cost.