[corvettetonybone]

im relocating my battery box to the rear and underneath my truck. can i run my negative cable directly to the frame or do i need to run it back to the engine block for proper installation.

[boatbob2]

Hi,Yes,you can run the neg cable to the chassis at rear of truck,THEN at front (by engine) run another cable to the engine,also another to the firewall.

[302 Z28]

It is common practice to use the frame for grounding purposes, but for maximum electrical conductivity you should run a ground cable from the battery directly to the engine block. Also use a Ford solenoid in the trunk so that your positive cable is hot only when cranking.

Vince

[corvettetonybone]

just to make sure i understand..... neg. from batt. to frame, from frame to engine, from firewall to engine.

[302 Z28]

Originally Posted by corvettetonybone

just to make sure i understand..... neg. from batt. to frame, from frame to engine, from firewall to engine.

Yes, if that is what you want to do. I would not do it that way. You asked if you need to run a negative cable all the way to the engine, and that is the best way to do it.

Vince

[Big Don]

You can ground the battery to the frame... Period. Thats what it is. The ground or electrical bond to complete the circuit. The frame becomes part of the ground circuit and will act the same as running the wire to someplace you were thinking about. Whatever that place was???? The ground is the ground the frame around.

Bonding shunts, grounding straps are needed between the body and the engine block to the frame. One from the engine to the frame, one from the engine to the firewall and one from the firewall to the frame.

Aside: Why are you thinking about putting the battery source so far away from the point of use? Electrical performance is greatly diminished by the distance of current transmission. In other words, the closer you put the battery to the mainload, the better the system will work.

The idea you are using for battery location will cause you to increase the positive wire size by at least two sizes so it can carry the additional current demands because of the load of transmission over such a long distance. Keep lots of starters handy.

Jag and Audi and other car manufacturers have tried this practice for many years... It didn't work for them and they eventually learned to put it up front near the STARTER, which is the major load demand device, correct? I have always mounted the battery as close to the starter as possible, within reason, so I can use as short of cable as possible. Just makes good electrical sense. As far as mounting in the system a remote solenoid to the equation and then additional wiring to activate it,,,, say what?? Thats kinda like putting the light switch to your bedroom on the breaker panel out in the breezeway. I don't get it.

Probably sorry you asked this question?

[302 Z28]

BigDon, the practice of placing a battery in the trunk or rear of a vehicle has been done by rodders for eons and has worked. Battery cables should be of sufficient size regardless of where the battery is located. The voltage drop involved with a trunk or rear mounted battery vs an engine compartment mounted battery is negligible when proper cable sizing is practiced. Granted some of the marginal battery cable sizes we have seen on cars today is questionable if used to place the battery in the trunk. We really should not be using any cable smaller than 1/0 wherever the battery is located. To say that rear battery installations never work is very misleading. The applications of proper rear battery locations has been discussed in great detail on this site and others and it is a proven practice. Having said that, just to clear up some possible misinformation, ground straps from engine to frame, battery to frame, and from body to frame are still required. The use of a dedicated positive ground cable eliminates any electrical resistance the frame has and will enhance the operation of the starter, not degrade it.

And why would he be sorry he asked the question?

Vince

[fast68]

more grounds the better, cant have too many grounds!

run cable from frame to engine and engine or frame to firewall and you'll be more than plenty good to go forever and ever

i have done this to many daily drivers i have had in the past

it helps things to work better

including the starter and lights and so on

[Big Don]

[QUOTE=302 Z28]BigDon, the practice of placing a battery in the trunk or rear of a vehicle has been done by rodders for eons and has worked. Battery cables should be of sufficient size regardless of where the battery is located. The voltage drop involved with a trunk or rear mounted battery vs an engine compartment mounted battery is negligible when proper cable sizing is practiced. Granted some of the marginal battery cable sizes we have seen on cars today is questionable if used to place the battery in the trunk. We really should not be using any cable smaller than 1/0 wherever the battery is located. To say that rear battery installations never work is very misleading. The applications of proper rear battery locations has been discussed in great detail on this site and others and it is a proven practice. Having said that, just to clear up some possible misinformation, ground straps from engine to frame, battery to frame, and from body to frame are still required. The use of a dedicated positive ground cable eliminates any electrical resistance the frame has and will enhance the operation of the starter, not degrade it.

*******************************
My thoughtful reply:-)

I thought he might be sorry he asked the question because of the myriad of opinions he might get. It looks like I was right.

After building cars for over 35 years one begins to learn things that do work well and things that do not. True, lots of rodders etc. do mount the battery in the rear, agreed. The only fact I was trying to point out was the amount of resistence there was in a few feet of braided extra wire needed to get the B+ power to the starter (the red wire). Granted the idea will work and many people have used this setup. Having been a industrial and control electrician for many years, now retired, the understanding of the ohms law becomes a major concern in this application because it is a DC circuit;

A dedicated ground lead???? The only way this could be considered would be to isolated the engine from the rest of the car electrically and you just stated that you suggested that he add ground leads from everywhere else, and this simply defeats the idea of an isolated, or dedicated ground lead. The frame is a very large low resistence buss bar, far better then any copper stranded wire run directly to the engine block. That idea may sound clever, but the electricity will not simply shortcut too that wire. The circuit will use the whole of the chassis anyway. The dedicated ground (as you have labeled it) won't do anything to enhance the performance of the electrical circuit. Take a deep breath, count to ten, and then think about what you are saying in regards to this so called dedicated ground wire. Common sense and simple logic would dictate that the idea is just plain incorrect. Again, a ground is a ground is a ground.

The whole of the bonded materials of the WHOLE circuit are in play at all times on the ground side of this type of DC circuit. The amperage, ohms, and voltage load on the battery and wire are the same no matter how the ground terminal is hooked. The only thing that (your dedicated wire) will do is increase the amount of distance the load has to travel through a small long section of wire, rather then if he hooked up the ground to the frame somewhere near the battery. There is less resistence in the frame and body then there is in a battery cable.

Think of this as a water pipe. A small pipe causes the same amount of water handled in a larger pipe to take ten times the pressure to move the same amount of water, the same distance, in the same time frame... The frame of the car is a much larger water pipe then the battery cable.

How about thinking in the realm of jumper cables. Small gauge wire jumpers always get hot as soon as the load is applied, right? How about when you do the same thing with heavy duty jumpers? Better right? Now clip the ground jumper, bumper to bumper and repeat the jump start. The wires don't get hot do they? Why????

I hope this clears up my position on the subject. And I certainly do not mean to offend you in any way. Your response seemed mean spirited, as if to assume that you were somehow more in the know then the rest of us grease monkeys. I sure hope that I mis-read your tone..:-)

[302 Z28]

Originally Posted by Big Don

Your response seemed mean spirited, as if to assume that you were somehow more in the know then the rest of us grease monkeys. I sure hope that I mis-read your tone..:-)

You did, I am curious to know just what it was that I said that you took as "mean spirited".

Vince

[Crosley]

yep frames are metal , but they get rusty , dirty at joints and replated places...

I usually run a ground to the frame or uni-body section when batt is in the trunk. I also add a 8 gauge ground wire that runs from the batt up to the engine block.

As pointed out the proper ground is often over looked

[corvettetonybone]

WOW ! ok. hmmmm. thouroughly confused now. {big don} i believe everyone has made a valid point and they all seem to make since. i am relocating the battery for the added space under the hood and also to eliminate the eyesore of the battery and cables. maybe not such a good idea but thats what i need to do to prevent other complications with my project. So you are saying the shorter the neg. cable right to the frame is all i need period. everyone else says i need to ground in several places. i understand your theory but what would be the advantage or reason to all of the extra grounding ? isnt that the way they have done it from the factory or has someone just started this extra wiring fad.. i dont know. sorry everybody, sure didnt mean to start a feud but i guess this bring out all the options that will work. i appreciate all the input, thanks tony

[302 Z28]

Whichever way you go, you still need ground straps from battery (-) to frame, fame to engine, fame to body(if steel), and frame to engine. The point I was trying to make is that copper is a superior conductor to steel and an appropriately sized cable from battery (-) to engine block will enhance starter operation and eliminate any potential ground problems with using the frame as the only ground.

Vince

[malc]

I´ve had the battery relocated to the trunk in my Camaro for many years now, this is the latest setup which works just fine.
The battery ground is to the sheetmetal at the rear, I have a ground up front engine to body.

Here´s a pic taken during the installation.


For safety´s sake the solenoid should be in the rear as well so the positive cable to starter is live only during cranking.

[powerrodsmike]

Any car I wire gets a ground lead all the way from the battery to the engine, where ever it is located. I also run a dedicated ground from the fuel tank to the fuel gauge, as well as a dedicated ground from the engine to the gauges. A seperate ground from the motor to frame, from motor to body and I make sure the alternator is grounded. All connections are made to clean steel, using star washers. Fiberglass cars get even more grounds.

I have found through my experience that will remove any doubt about ground related gauge or charging issues. I own a street rod shop, and wire cars and motorcycles as part of my services. (I have been doing auto and motorcycle wiring since I was 14...and learned a few things in the last 34 years). I have found that if there is an issue, and you have an unbroken dedicated ground lead, it is usually related to the failing component, and not a poor ground. In my experience, when there is a question about a failing component, the first statement a customer service tech will tell you is to check your grounds.

I wired a steel bodied 35 Ford not too long ago and used the guys supplied gauges, a set of classic instruments...the temp gauge fluctuated badly, and customer service at classic was adamant that it was a bad ground...when I showed my customer the unbroken dedicated lead with soldered and shrinkwrapped connectors that went from the intake manifold bolt to the gauges, that I had installed as a regular part of my wiring installation, he had no more reason to blame me for the issue.

The first action you take on an OEM installation when there is a charging ,starting or electrical issue is to check the grounds...the connections corrode, at the point of connection, as well as inside the connector itself. These connections were designed by educated automotive engineers yet they still fail after time. Vibration, dissimilar metals, moisture all contribute to connector deterioration. Less connections means less can go wrong.


This is not a new fad, it is just a common sense approach to avoiding problems down the road.

You can read this thread and decide which way to wire your car, based on who's opinion you like the best.


later, mikey