Battery grounding questions

[colorado51]

Hey all,

I have a few simple questions on battery grounding.

My battery is mounted in the trunk of my 51 Chev, is it best to ground it to the frame, or the trunk floor (or both)? Also, is it best to run a ground strap from the engine to the frame?

Thanks!

[skipperman]

The BEST way ( and reccommended by ALL wiring companies AND done by ALL OEM...) is to run the ground directly to the MOTOR .....NOT the frame .....

Jersey Skip

[Petejoe]

You must ground your battery to the engine. Run welding cable size wire for that distance. Also use the same wire for the positive cable.
Yes, be sure to run a ground strap from the engine to the frame

[Digger_Dave]

[ QUOTE ]
You must ground your battery to the engine. Run welding cable size wire for that distance. Also use the same wire for the positive cable.
Yes, be sure to run a ground strap from the engine to the frame

[/ QUOTE ]

AND a ground strap to the body. Either from the battery OR the engine.
Without a GOOD ground on the body, accesories tend to "act up."

[Bruce Lancaster]

Also, parenthetically, grounding is the root of all evil on olde cars. I have a shotgun approach to grounding troubles that has successfully cleared up multiple problems on elderly cars: Get some 10 gauge wire, terminals, and a hatful of star washers. Run ground wires from instrument cluster, generetor case, voltage reg base, distributor case, and grounding screws for headlights back to a central location that can be tied to your battery ground directly. Also do any other bits you consider troublesome or important, and include ground wires in things like head or tail lights that are mounted on stands that force the ground through a maze of painted or rusted bolt connections. I do this in preference to attacking individual ground problems, and usually manage to run the ground wires taped under existing harnesses to avoid clutter.
On older cars, an additional trick is to add star washers under bolts and screws in things like tail lights and to create some extra bite in ball-joint headlight mounts by making chisel or punch indentations that can bite through paint or crud when tightened. This is of course in addition to the battery ground connections mentioned above. Remember, ALL old cars have ground issues--if they are finished, there is too much paint on all junctures; if unfinished, all the grounding points are rusted/dirty/loose or whatever.

[Digger_Dave]

Bruce, maybe the best way to get people to see how important "GROUNDS" are; is to explain that ANYTHING electrical needs TWO "paths." In a 12 volt system most manufacturers do/did ground things like gauges, lights, horn and even the starter by relying on the engine, frame or body for the second PATH.

With the introduction of "tough" paints, (and finishes like powder coating) it has become difficult to just "bolt things in" and expect them to be grounded.

Like you I now use a "GROUND COLLECTION WIRE" in any wiring jobs that I do. It runs to the front and the back and is directly connected to the ground post of the battery.
This also includes a ground cable (equal in size to the main cable) to the engine block.

Most so called "hot start" problems are usually caused by poor grounding at the engine or poor connections between the battery, frame and engine.

The scraping away paint from the frame or the body only introduces a possible corrosion point that in turn becomes a "resistance" connection. Especially if you drive your vehicle on any roads that use salt. (or Bonneville, if you go!)

[AnimalAin]

As noted above, it cannot be overemphasized how important good grounding is. My roadster just about drove me nuts trying to find a charging problem. Turned out to be a bad battery ground. It made a believer out of me......

[Bruce Lancaster]

One of the interesting things is how electricity SEEKS a ground when there isn't one where there should be--this is why you get totally weird stuff, like seemingly unrelated lights coming on, instrument lights trying to flash with the turn signals, and so on. Even Detroit forgets--seventies GM cars had nearly ungrounded engines due to the same idiot cost cutting that produced all those aluminum battery cables, and became famous for odd things like MELTING their trans kickdown cables as starter juice went looking for a way home. If you have anything going on that isn't simply a dead bulb or broken wire, think ground first. Troubles that arrive in multiples are almost always related to a common ground. If you like totally reliable electrics, one key is to pretend the whole car is plastic and give everything you care about a real ground. There is grease available for electrical stuff, I forget its designation, that should go on when you have to go to bare unplated metal, as on engine block and frame. This stuff is also good insurance for exposed light sockets, especially if you live in the salt/rust belt.

[Petejoe]

[ QUOTE ]
grease available for electrical stuff, I forget its designation, that should go on when you have to go to bare unplated metal, as on engine block and frame

[/ QUOTE ]

Dielectric Grease. From a localized rustbelter http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif
Good info Bruce! thanks

[Missing Link]

One other thing to avoid are those bullshit $5.00 quick disconnect battery hook-ups. You know those ones you always see at the swap meets, the ones with the green knob (silent "k") Supposed to hook into the negative (ground) battery terminal and cable...those things suck ass and just create more problems. If you need a disconnect switch get a good one.

[tommy]

[ QUOTE ]

Most so called "hot start" problems are usually caused by poor grounding at the engine or poor connections between the battery, frame and engine.



[/ QUOTE ]

I fought a hot start problem for a year until I moved the battery ground from a welded stud on the frame to a bolt in the trans tailshaft. After you chase that goose once you'll be convinced.

[colorado51]

Thanks for all the good info!

The previous owner of my car put the battery in the trunk and just ran the ground right to the trunk floor. And the engine isn’t grounded either.

I guess I’m lucky that the damn car has been starting & running!

Anyway, I will be doing it the right way this weekend.

Thanks!

[Digger_Dave]

[ QUOTE ]
One of the interesting things is how electricity SEEKS a ground when there isn't one where there should be--

[/ QUOTE ]

As a "post mortem" to this; I was called in on an insurance claim of a car owner who had just fired up his new rod for the first time. The insurance company hired me to investigate the cause of the damage claim.

He had forgotten to (or didn't) run a ground strap from the frame to the engine. (the battery was grounded to the frame in the trunk) He ALSO had bypassed the neutral safty switch on the auto trans. When he hit the starter for the first time, (the transmission wasn't in neutral!) the current draw melted the throttle cable (stainless steel) WIDE OPEN and the car shot through the front of the garage.

Damage; engine lunched, body suffered serious damage on the front end while going through the front wall of the garage, THEN the roof of the garage collapsed on top of the car! Car was a write off, garage $12,000 damage!

Claim denied.

[C9]

[ QUOTE ]
the current draw melted the throttle cable (stainless steel) WIDE OPEN and the car shot through the front of the garage.


[/ QUOTE ]

That's an interesting one.

Mebbe he should have used the high electrical capacity 1/4" stainless throttle rod.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/tongue.gif

Ok . . . so I'm bad . . . couldn't resist.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Bruce Lancaster]

"Claim denied."

Yeah. My path to minimal competence in auto electrics was long and bloody, filled with moments of sudden darkness, dead signals, small but pungent fires, etc.. If you don't know your way around wiring, READ, MARK, LEARN, AND INWARDLY DIGEST everything that comes up on the HAMB on this. Learning from scratch is too risky, and modern driving conditions and litigation both have zero tolerance for sudden failures in traffic.

[Digger_Dave]

[ QUOTE ]
If you don't know your way around wiring, READ, MARK, LEARN, AND INWARDLY DIGEST everything that comes up on the HAMB on this. Learning from scratch is too risky, and modern driving conditions and litigation both have zero tolerance for sudden failures in traffic.

[/ QUOTE ]

Sadly; so very true.

My one gripe is; Almost ALL safety inspections (NSRA for example) DON'T inspect WIRING. I realize how difficult inspecting wiring is; but when I see frayed wires (insulation gone) and poor conections standing out in full view, I want to take the owner aside and tell them that they are playing "Russian Roulette" with all the chambers loaded.

If there is ONE piece of advise I can give, it is DON'T USE ORIGINAL WIRING HARNESSES FOR ANY PROJECT OVER 15 YEARS OLD! REPLACE THE OLD HARNESS WITH A NEW ONE!!

I have done at least five insurance claim investigations on vehicles where old wiring was found to be the cause of a fire!