The Stovebolt Site Forums The Shop Area The Electrical Bay 6V grounding question????

I read through the Tech Tips and found some useful info but not the exact answer to a question I now have.

Due to some lackluster starting power I decided to take a stab at fixing the problem yesterday. I made a trip to the FLAPS and bought a new 4 ga grounding cable that I installed, replacing the original woven negative strap coming off the battery to the frame. I sanded off the rust at the point of contact on the frame while at it. Unable to find a positive cable any larger than the 4 ga that I already had, I simply cut off the end of the original and attached it nicely to a brand new battery connector, then reattached it to the starter. I just returned from NAPA where they ordered an original style braided grounding strap which I will install between the engine block and the frame. ($14.95) The Tech Tip article emphasized the need for a 6V system to be well grounded, so my question is this........ should I install the old, replaced grounding strap for additional grounding? There are two threaded holes just behind the downdraft tube I could use and run the strap to the frame easily. I know it "won't hurt anything to do it", but want to know if it would provide superior grounding and make my starting easier?

Many thanks!

The standard ground routes on Advance-Design trucks were:

- negative battery post to frame (behind battery). I prefer to run a long ground cable from the battery to a starter-to-clutch housing mounting bolt.
- frame to a bolt on the clutch housing (a bolt that holds the foot-starter mechanism to the clutch housing)
- (not sure if this is standard) other side of the clutch housing to the other side of the frame
- (1954 spec for use with radio) head bolt (behind coil) to firewall (bolt on firewall-to-fender rod).

Also, to stop rust and corrosion AND to enhance electrical conduction, an anti-oxidant conductive grease is beneficial. NAPA: BK 7652569

If there is a welding supply store in your area, check into getting a ground cable made up from #0 or larger welding cable. The #4 cable you can get from the FLAPS is going to be a bit under-capacity for good operation with a 6V system. Most welding supply places will have a way of doing a very low-resistance crimp connection of terminal lugs onto the cable, and welding cable is made from hundreds of strands of hair-fine wire that will have lower resistance than a similar-diameter piece of battery cable. For the absolute lowest-resistance terminal connections, use a Propane torch and lots of rosin-core solder to attach the terminal lugs. That's how we built battery cables for the race cars with 11:1 compression or higher.
Jerry

Most FLAPS can order a "0" gauge cable if the counter person want's to take the time to do so. I got mine at the local Bumper To Bumper.

Thanks for the comments so far, but I'm still curious to know if by adding the additional ground strap I've helped my 6V electrical system perform better?

Also, didn't the original system setup use 4 ga material (strap or cables)? O size cable might carry more load but the new 4 ga strap I installed today should be adequate, correct?

Thanks.

The bugaboo in 6 volt systems is something called "voltage drop". Think of a piece of wire as a water hose, with the voltage being the pressure that forces the water through it, and the current being the gallons per hour of water flow. A big hose with the same pressure against it will flow more water than a small one, right? By the same logic, losing a little pressure on the big hose will have less of an effect on total flow than if the small hose lost the same amount of pressure.

Current flow (amperes) is what makes a starter do its job, and whatever voltage is consumed pushing current through a too-small wire isn't there to push the current through the starter windings. Bigger is always better where wire size is concerned, and 4 gauge is just TOO SMALL to work with a 6 volt system if it's the only path for the current to get from the starter housing back to the battery. That's why people opt for a ground cable attached directly to the engine/transmission castings, rather than do it the factory way with two cables, one grounded to the frame, and another one frame to engine. That's twice as many connections to get loose or dirty, and more places to lose voltage. Run the 0 gauge battery ground to the engine, and let the little 4 gauge engine-to-frame jumper be the ground for the headlights, horn, heater blower, and other body-mounted accessories.
Jerry

Thanks to Tim, Tiny, and Jerry for your good responses. I've now learned that "bigger is better" when it comes to wiring cables, so when it's time to replace I'll go bigger than 4 ga.
I'm trying to keep the 6V system intact rather than converting to 12 but sometimes I wonder why. Switching would really solve a lot of problems.

Thanks again fellas!!

Chuck

If you were further north, a conversion to 12 volts would make a lot more sense. Since you don't have to contend with starting in sub-zero temps like some of our Canuck buddies, or the guys in Alaska, all you really need to do is use big cables, keep the connections clean and tight, and keep the engine tuned up. I ran a 47 Mercury with an 11:1 compression flathead V-8 on 6 volts for 13 years, and as long as I did my homework, it was very reliable. There's no reason a stovebolt with half that much compression shouldn't work OK.
Jerry

An update on my electrical upgrade.......

I bought and installed the new braided ground strap between the block and frame. I also went ahead and reused the old one.
I bolted it to the block just behind the downdraft tube and ran it over to the frame. Bolted up nicely. I can't report that the starting is greatly improved, but it does crank a bit faster since replacing all the old cables and ground strap. Had the battery checked and it showed it didn't have a lot of reserve cold crank amps in it after a full charge, so I suspect that the battery is adding to the poor starting performance. It spins the starter pretty good but if the engine doesn't start in the first few seconds then I don't have any reserve power to continue cranking on subsequent trys. It's good for now, but I see a new battery in my future.

Thanks everyone for your input.

Chuck

There's something called a "series resistance test" which involves measuring the voltage drop at every connection from the positive battery post to the starter, to the negative post. By using a low-reading voltmeter and connecting to each side of every connection, it's easy to spot the dirty, high-resistance connections. No connection anywhere in a 6-volt starting system should have over 1/10 volt drop, and the ground side voltage drop should be almost zero at every connection. All it takes is one high-resistance connection to kill the cranking speed.
Jerry

I have sometimes been lucky enough to find bad connections when I touch em. Most of time I do not get burned.

The voltage drop method is more accurate.
Dan Bentler

Jerry, After reading posts from guys like yourself I feel like a total idiot. I am a self trained shade mechanic and don't know squat about electrical. I always shy'd away from learning about it because it seemed too complicated. I favored wrenches. Anyway, I was in HF one day and picked up a little volt meter, or such, they had on sale and have it in my tool box. I wouldn't even know know how to go about checking the voltage drop you talked about although I'm willing to try. I think I've repaired or replaced all the obvious cables and grounds on the truck, so don't know there's anything else I could fix, but if you think checking all the connections with the volt meter is a good idea I'll learn how to do it. Like I said, I think the battery is beginning to show it's age and should be replaced.

Chuck

Checking voltage drop isn't rocket science. Just touch the meter leads to both sides of a connection with current flowing. For instance, put one voltmeter lead to the battery post, and the other one to the cable terminal while someone spins the starter. The meter will read the fraction of a volt that is required to push the current through that particular connection. If the connection is loose or dirty, it uses up too much voltage. Several of those bad connections in series with each other use up voltage that would normally be available to run the starter. If you use a wire brush and scrub the terminals before bolting them together tightly, the resistance will be minimized. It's also possible to check for internally corroded cables, etc. by touching the voltmeter leads to both ends of the cable with current flowing. Cables should have virtually no voltage drop. If voltage loss can be measured, replace the cable.
Jerry

Make sure you have good grounds in the electrical system.

I have a good 6 volt battery that passes the load test. I was showing that (6 volts) across the battery but at the end of the positive cable it was showing 2-3 volts. I thought it was the ground at the engine. I was wrong it was the battery ground.

Lesson learned

On a 55 2nd I used to have I could not get the tail lights to work properly. I found grounding the bed to the frame was the problem.

Make sure you always have good grounds.

Best of luck

Thanks Jerry for the instructions on how to check for voltage drop. I'll tinker with that this weekend. I'm hoping there won't be any drops noticed due to the fact that after cleaning off all paint, dirt and rust at points of connection, I replaced the grounding strap, negative cable and the positive cable battery connector. Connections are good and tight. Even reinstalled the old ground strap as an additional negative ground between the engine and frame.

Thanks Dennis for the reminder to always have good grounds. I hope I have done that.

Chuck

tim, i thought you were on to something big here . i called my napa and gave them the part # and they said yup we got it. so after work i rush up there only to see a little bottle of copper anti sieze. i walked out with dielectric grease instead in case i end up with a cold blister

Hello, Mike,

That NAPA copper anti-seize is an antioxidant and is conductive. Eastwoods used to sell a similar product (at 5x the cost) called Kopr-Shield.

A regular dielectric grease acts as an anti-oxidant but is non conductive. I would not use a dielectric grease on ground cable connections.

Here is what NAPA showed as a product description:

Description of NAPA product:

(Conductive) Anti-Seize Compound & Lubricant, 4 oz

NAPA Part: BK 7652569
Product Line: Balkamp

Features_&_Benefits

Premium Quality Copper Anti-Seize & Thread Lubricant That May Be Used to Prevent Seizing, Corrosion & Galling Where High Temperature Conditions Exist, Contains High Percentage Of Micro-Fine Copper Flakes, Provides Good Electrical Conductivity

I've always made it a practice to assemble electrical connections clean, tight, and DRY, then coat them with anti-corrosive compounds or paint if necessary. Nothing beats a solid metal-to-metal connection, with nothing whatsoever between the conductors. Isolating the outside of the connection from corrosive influence is great, but don't put anything between the pieces that carry the current.
Jerry

Howdee, lots of good information here.
I have a problem with me 53 GMC 228, 6V Pos. gnd. When I start it from cold, 107deg outside, it will start and run and charge. When I turn it off after it is up to temp and try to re-start it doesn't have enough umph to barely turn over the engine. Volt drop across the battery while cranking is 4.2 volts. I thought that the armature was bad so I had it rebuilt. Same story after rebuild.
Any ideas ?
thanks

Did you read any of the above post before posting your question?

I read all of it. All ground circuits are solid with original cabling. V drops <.1V
thats why I'm asking.

It sounds like the engine is tightening up a little when it's hot. Have somebody load test the battery to 4.2 volts and see how much current it's drawing from the battery. If the current draw is over about 300 amps, the problem is with the engine, not the starter. Also, try pumping the gas pedal a few times before a hot start to create a momentary flooding condition. If it cranks faster while clearing the flood, your ignition timing is advanced too far. If it's got a stomp start, try checking cranking speed with the ignition off.
Jerry

What is meant by "original cabling"?

Are you referring to the cabling you found on the truck when you bought the truck? If so, that cable is suspect.

However, if you referring to cabling that meets "original" specifications, then it is probably 4 gauge or smaller and should be OK (the thicker the cable, meaning the smaller the gauge number, the better).

Jerry's advice is good, if everything else checks out OK (good battery, cable gauge on both leads, clean grounds/connections, and good starter). I had an engine that "tightened up" when hot - the solution, unfortunately, was a rebuild.

Hello, Please describe "stomp start". I just replaced the battery. < 1 year old. The previous battery had a damaged positive cell, closest to the post.
when cold it started the second I pressed the button.
After warming to >180deg I turned it off and waited 10 min. and the draw at the battery was 2 volts, didn't want to start.
Engine has original 83K miles.
thanks ya'll

foot operated (foot operated, direct contact type starter switch), foot start, or foot-actuated start, or foot-pedal start.

Mechanical Shift Starter (I have only seen this term in the Master Parts Catalog).

Maybe some people stomp on it when they have too small battery cables and they think that stomping on the foot-starter mechanism will give them more power?

Ok, thanks the "flooding" makes no difference. Original cabling is 1 AWG, a replacement apparently. I have new 2AWG cables will install this week end.
ideas welcome, timing advanced too far, weights in dist. not functioning,...?
Rich