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fr500c's avatar
fr500c
Explorer
May 03, 2022

Wiring battery combiner into 7 pin harness

Hey everyone. I've got my truck camper permanently on my 1998 GMC K3500 and unfortunately cannot easily access the 7pin harness to unplug when it is off the truck. I quickly realized that with it fully plugged in that the 12v charging cable from my 7pin harness will drain the truck batteries.

I have ordered a battery combiner and am looking for where to wire this in.***Link Removed***

Can I just splice this between the 12v wire going into the 7pin trailer plug? I can easily access that under the bed of the truck.

Is it that simple or am I missing something? Appreciate any help!
  • opnspaces's avatar
    opnspaces
    Navigator II
    May 03, 2022
    Aux A or Aux B were the two charge posts on my 1996 Suburban. I'll bet you you have wire on one of the two.
  • 2112's avatar
    2112
    Explorer II
    May 04, 2022
    Gdetrailer wrote:
    Instead, opt for a $8 12V relay which the coil is connected to the ignition keyed source which is powered only when engine is running.

    Common 12V relays are the "Bosch" cube style which are typically 30/40A which would be enough to cover the charge fuse.



    For overkill they do make a 70A Bosch style relay..
    I agree with this

    I used a few similar to These Cheap Chinese 80A Relays because they came with a Bosch compatible socket, thinking I would replace them with the Bosch 70A when they fail. 4 years later one is switching 120VAC ~12.5A and the other switches ~8.3A a few times a day Without issue using a 12VDC controller.

    You can use a fuse tap to access an accessory control voltage.

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