I thought I remembered reading something about not hooking accessories directly to the battery so that the battery management system could accurately measure charge, but now I can't seem to find it. Am I misremembering, or do I need to use a different point for constant 12V?

(This is for winch hookup, so near the front of the vehicle and high-current)

 

Are you going with a dual battery set-up?

 

I am not. I'm hoping that for my occasional use, planning to have the vehicle running while winching will be sufficient.

 

For the battery management, you have to run the negative through the chassis ground point. Be careful, the chassis point may not be able to handle the current needed for a winch.

 

Put it on a relay fired by a switch on an ACC circuit. Make sure the relay is rated for the high current draw.

 

The ACC circuit can not handle the amps no matter what relay you use.

 

I am sure the poster would run power for the high current circuit from the battery, not accessory power.

 

I'm not sure how your advice would be helpful. That would be the same as connecting it directly to the battery.

 

My winch is wired direclty up to the battery. Winches use some thick cables so they need to be hardwired to the battery. If you have a switch/relay it should go into whatever control box your winch has. In my case, no remote control box, I hookup the control cable whenever I need to use it.

 

The high current circuit in a relay (they do make them that handle up to 75 amps) does not run off the accessory. The accessory wire would be used to trip the high current circuit. Basics of relays. To state the accessory power can not handle the amps is a false statement if the relay is wired properly. The winch would not be running off the accessory power, only the relay would, which only draws well under 1 amp.

SPST Relay:
30 - Winch
87 - Battery
85- Ground
86 - Accessory Wire