Battery Relocation: How to Ground

[Gary RV_Wizard]

A pair of 8 gauge wires in parallel have much greater ampacity than a single 6 gauge, so YES as long as the end pairs are properly fitted to the terminals. Paralleling the wires just adds a bit of complication and potential failure points.

 

[RayIN]

re: 6ga wire and charging rate for the lithium battery. I suggest you look into this closely. Search here and irv2.com for proper methods to charge a lithium battery in an RV.

 

[Mark_K5LXP]

RayIN makes a good point, even if the loads are minimal I suspect there's a "typical" converter in place that could be upwards of 55A. Through some number of feet of 6ga plus unknown path of steel frame the voltage drop could be an issue. That's why I would not be using the steel frame for a current path, the copper will be limiting enough as it is. Depending on the converter it might just translate to increased recharge time but if it's doing any kind of sensing, it will not be measuring battery state correctly. My take on it would be to fully test things in whatever configuration is implemented before calling it done.

Mark B.
Albuquerque, NM

 

[Gary RV_Wizard]

The steel frame may not be a the best conductor but it's at least a 20/0 gauge path. I don't think you need to worry about its ampacity. The bottleneck is always the point where the battery cable attaches to the steel frame.

The converter/charge is limited by the hot side cable too, so whatever limit the 6 ga imposes, it affects charging as well as load.

 

[Mark_K5LXP]

Steel frames can exhibit quite a bit of voltage drop. Back in my radio install days I used to have to sell the idea of running a negative lead from the equipment to the battery ground point vs just poking a hole in the body or existing hole frame. Even at a tepid 20 or 30 amps a volt or more of drop could be observed between battery negative and the load. So at a minimum I would at least test it first to see if it was within a useable range. Even half a volt error would be enough to confuse a "smart" charger.

Mark B.
Albuquerque, NM

 

[Zulu Kono]

Thanks for all the replies! Ended up taking the two original 8 gauge wires and going straight down through the floor and onto the frame with them. Drilled a hole and ground off the paint around it, then repainted it when I was done. Working great so far. Those wires are red and white so I taped them together with black tape so a future owner might not be confused about a red wire coming off the negative terminal. The battery isn't yet secured in it's new compartment because I'm gonna put some foam cushioning under and around it first, which I don't have yet.