Dual Battery System Grounding Question

[jupp0r]

Probably a good idea to measure the resistance from your frame ground point to the negative terminal of the starter battery. Should be essentially zero, everything else will cause major headaches and/or be dangerous.

 

[Steve_P]

Always connect auxiliary batteries in parallel with the OEM battery.

Parallel simply means that the batteries are connected positive to positive and negative to negative, the length or composition of the conductors is not mentioned.

To minimize electrical resistance and maintain full output voltage at electrical devices, auxiliary batteries should be securely grounded to the vehicle engine block."

On my 208 Silverado the positive of the starter battery is directly connected to the master fuse on the firewall and the negative is directly connected to the engine block.
The positive of the auxiliary battery under the hood is directly connected to the master fuse on the firewall, through an isolator, and the negative is directly connected to the opposite side of the engine block.
The positive of the battery on my trailer is connected through the trailer connector to the power box stud under the hood of the truck which is connected to the master fuse. The negative of the trailer is connected through the trailer connector to the frame at the rear of my truck. The frame is bolted to the body and the body is connected to the engine block by a ground strap from fire wall.
All three batteries are connected in parallel.
The weak spot of the frame/body/engine block side of the circuit is the puny oem ground strap between the body and engine block. Some people will replace or double up that strap to lower resistance. It would probably be better to add a ground strap directly from the frame to the engine block.

 

[broncobowsher]

Also remember that the frame isn't a good ground. The engine is sitting on rubber mounts to the frame. The body is sitting on rubber mounts to the frame. You can get a good ground checking with a meter if you ground the frame to the engine with a scrap of 18 gauge wire. Meter shows continuity. But it will never pass any respectable amount of current.

I once installed a winch and it was grounded to the frame. Took about 2 weeks of chasing it down to find the frame ground really sucks. Then thought about it. There really isn't any electrical load on the frame, and it is all rubber mounted.

 

[Nailhead]

I’m planning on running a ground cable from the threaded stud on the truck battery directly to the negative post on the camper battery bank through a military-type terminal clamp. Might as well go right from the source.


Sent from my iPad using Tapatalk