I am mounting dual Optima yellow tops in the rear of my 4Runner, hanging somewhat where the spare used to. Seems to me its reasonable to take the grounds right to the frame at the batteries, and take the power cables up front where a solenoid will connect them in parallel only when the ignition is on. I'm running 1/0 welding cable.

Your thoughts?

I suppose that would work given a good solid, clean connection to bare steel.

I ran cables from my dual batteries up though a pair of quick disconnects (power and ground cables) and then tied the 2 ground cable to the frame up near the front shock mounts. This way I could still keep the batteries separate at the connectors so I could put them in series if needed, for example for welding.

Also, I kept all the heavy frame ground points at the same location, so the original frame ground, my two new ones and the winch all come back to one point to minimize having 100s of amps of current flowing though parts of the frame.

Hmmm. That does give one pause.

[theory mode, probably only tangentially related to reality]
I suppose the frame would provide a near 0-ohm ground plane, unless it breaks (!), so in theory it should be fine. All that steel should conduct much better than even two 1/0 cables... assuming, as you say, that the connection is the cleanest one on the truck and remains so. Unless the ground plane was broken, it seems unlikely that any current would 'look' for another path.

[contrarian mode]
On the other hand, hundreds of amps can cause odd behavior even in the presence of one ohm.

Any comment from others?

Steel only has 12% of the conductivity of copper, so "all that steel" in the frame is not quite as significant. It works out to about the same resistance for 2 parallel 1/0 copper cables as one boxed fram rail. So it would basically be a wash as far as that goes.

In my installation, the more important point was maintaining a common connection point on the frame for all the heavy ground connections. If all the ground wires are connected to the same point, there is less chance of ground loops and other elusive electrical problems related to grounding. On the other hand, at $1.50 or more per foot of 1/0 cable, you could save some money by keeping the use of it to a minimum and connecting to the frame as close as possible.

Ground is ground is ground. Bottom line you have everything grounded to the frame at one point or another. Running cable all the way to the front to keep the back of the frame from shorting on something will not gain you anything since the frame is still grounded. I would use less cable and save your money. If you break your frame, a missing ground is the least of your worries.

One common ground point has its disadvantages too. For example if you have a bad ground instead of loosing only one item you will loose everything. Or it is a lot easier to snag a wire and rip it loose than it is to snag your frame and break the connection. Eliminating 1 of those wires reduces the chances of catching one by half.

4crawler, Please do not take this the wrong way. I am not questioning your decision to run a ground cable nor am I saying that it could not be done right. Just exploring the options pros and cons.

Not sure how I would do it myself.

tangentially ????

Is that a word? If not can I add it to my Darins dictionary of backwoods mechanical knowledge? Maybe I are just a dumb.

Hehe, heck Bill....be like Nike and just do it. Remember not to create something that will get in the way of your 3.4L swap. Also make sure that stuff is installed properly so you dont leave burn marks in the flooring the shape of your feet. I learned that a professional electrician is better suited for house wiring after experiencing this one myself. <img src="/forums/images/graemlins/shiner.gif" alt="" />

~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

Agreed, if everything is connected well, ground is ground. But with my batteries near the back fo the truck, the thought of 400 amps moving through the frame, past the ECU and engine electronics to reach the winch up front was not terribly appealing. Maybe it would be alright, but I didn't want to find out it wasn't when the truck was hanging by the cable winching up a dry waterfall and finding the engine died everytime I hit the winch button or something.

My power and ground cables run together via 2-conductor disconnects, and are up inside the frame rails, so fairly well protected. And a common ground has the advantage of only having one place to fail. If I have a grounding problem, I know exactly which point it is, since there is only one. Granted, if it fails, I'll have everything die, but that is far easier to troubleshoot than figuring out which of several points might be at fault. My ground point is a 7/16" bolt through the frame, all the heavy ground lugs are stacked on it and then clamped to the frame. Never had any problems with that attachment point in 6 years, so I'm pretty happy with it.

Good discussion.


Yep, made a living for a while chasing just that sort of thing.


Until you add hundreds of amps. Its like saying glass is a solid, yeah-but, not really. Not under some conditions or perspectives.


Losing all grounds instead of some of them would actually be preferable, otherwise a high current device starts looking for a return loop - maybe through the dash. Bzzzzzzzapppp!


There's the rub.

Sounds like if I am willing to risk the downside and mitigate it by bonding with care, it would work to just cable the positives. Not like I couldn't add it later if I get odd behavior - barring fires or letting the magic smoke out of something.

I do notice Warn recommends taking the ground all the way to the battery, but then is that the engineers, accountants, or the lawyers talking? If the cost is borne by others, then darn the cost. Otherwise,...

Since my batteries are inaccessible and not located near the frame, I had to run the cables from them out to a more convenient location so that I could disconnect or reconfigure them. From that point forward to where I have the common ground point was only 1.5'-2' so it only "cost" me 3'-4' more cable to run the separate grounds. So in the whole scope of the project, saving $5-6 on a few feet of cable was just not that big a deal.

In my daily driver, I'm planning to relocate the single battery back into the bed and will be running separate power and ground cables (1/0) to the front. It is unibody construction, so no heavy steel frame to bolt the ground to.

What do you drive that has a bed but is unibody? An old Rabbit pickup or something?