6 Volt......Shouldn't You Need Big Fat Ground Wire?

L

leon bee

Well-known member
I can wire most anything, but don't always understand the physics of it. From my Studebaker and tractor days, I know to use real heavy wire all the way to the starter. And it's always good if you can get the ground attached near the starter. I was looking at Brillman, and every one of those braided battery ground straps says 2 gauge. But you wouldn't run 2 gauge to the starter. I haven't seen a heavier ground strap than that- and never really paid attention before.

So, after the electricity has gotten to the starter is it not so important how easy it gets back to the battery? Any thoughts appreciated. Thanks!
 
I use two OEM style 6V flat braided ground straps connected together and an OEM positive battery cable. One flat braided strap ground strap goes from the (-) battery to the body where it is bolted to another flat braided ground strap that goes to a bolt on the bellhousing. A black positive cable goes from the + side of the solenoid to the starter and the + black battery cable also bolts to that same solenoid terminal. Keep in mind my car has been converted to 12V, negative ground. I used the same cables when it was 6V, + ground.
https://cgfordparts.com/wwwsectionf...ground cables. Maybe something could be made.
 

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It´s about lenght to so a short 2 gauge ground have same resistance as a longer thick wire needed to feed the current from battery to starter.
The longer wire the thicker it needs to be...or the losses in the cable will be to big.
 
You are correct, the current flow to the starter needs to equal the current flow from the starter to ground and back to the battery. But as flatheadmurre pointed out, length plays a part. And 6v requires approximately twice the current flow as 12v.
 
With a new solenoid, rebuilt starter (converted to 12v) and new ring gear on the flywheel, I was still having the occasional problem getting the starter to spin the engine. The starter would often crank only half a revolution and then stall. After repeated attempts it would make it past the stall point and spin the engine to start. I attributed the problem to a new rebuild being a bit tight, and 9.5 compression. I added a #2 cable directly from the battery negative (ground) terminal to under the starter mounting bolt, and the problem cleared up.

So that confirms your notion that the ground path is as important as the power path, which on the early Ford must get through the starter to bell housing connection, through a cast iron block, and through cable connections from block to firewall to battery. A few tenths of an Ohm electrical resistance anywhere in that path would kill starter performance.
 
I always replace all my battery/starter cables with 2/0 (00) welding cable.

I also use asphalt cloth wire looms over the cable to give it a "more" old car friendly look. Just make sure to put the loom on before putting both ends on.
 
My '51 is original enough to have the factory cables and ground strap. With an Optima and clean connections, it turns over as good as any car I've had.
 
This is interesting, thanks guys.

What's the latest on the Optimas? I read old posts all the time, and a while back some were disappointed in them. I already bought me a 6v battery tender, but haven't sprung for a battery yet.
 
Haven't had issues with my 6volt Optimas. One bought about 8yrs ago the other 4yrs ago. But I always disconnect them when sitting or even when I park for a bit. Also charge them often.

Your starter grounds to the engine. Sometime on a new rebuilt the paint can effect the conductivity. Same with with an older unit that may have some dirt or grime between the contact surfaces. Personally I like to have a ground running to frame, frame to body and engine.

Most electrical issues are due to ground issues.
 
Re : Optima's. The word is that they moved their manufacturing operation to Mexico about 20 years ago. There were problems that arose from the move that caused some of the batteries to be defective. From what I know, the batteries now are as good as they used to be. I have had two over the last 15 or so years; the first lasted about 12 years and I'm on my fourth or fifth year on my current one. One thing that did impress me is that a representative from Johnson Controls was on the H.A.M.B. when they had problems who tried to field complaints and explain the company's position. The guy took a lot of heat and handled it well. The only other problem is that the U.S. Military uses them and they were in short supply during the Iraq "conflagration". Because of the requirements of the military, the 6 volt batteries grew a little taller and are harder to fit into the faux Ford cases we love to use.

I wouldn't consider using anything else for 6 volt applications.
 
I also have had very good service from my 6V Optimas. The first one was replaced after 13 years-it never died, just got weaker, and is still used in the shop for testing. The new one is 3 years old and doing great.
I also have a 12V red top that's going on 12 years and still strong.
 
I have a red top 12 volt optima in my 1988 Hi-Lux Toyota ute which is 18 years old. Many emergency services use optima batteries. I use 6 volt ones in old cars and they are the best. Regards. Kevin.
 
I have a 6 volt in my 48 going on 3 years, no problems yet, I put a 12 volt in my frontier and it lasted a year and no longer would hold a charge. I was given a full refund and opted for another brand.
 
drolston said:
With a new solenoid, rebuilt starter (converted to 12v) and new ring gear on the flywheel, I was still having the occasional problem getting the starter to spin the engine. The starter would often crank only half a revolution and then stall. After repeated attempts it would make it past the stall point and spin the engine to start. I attributed the problem to a new rebuild being a bit tight, and 9.5 compression. I added a #2 cable directly from the battery negative (ground) terminal to under the starter mounting bolt, and the problem cleared up.

So that confirms your notion that the ground path is as important as the power path, which on the early Ford must get through the starter to bell housing connection, through a cast iron block, and through cable connections from block to firewall to battery. A few tenths of an Ohm electrical resistance anywhere in that path would kill starter performance.
Click to expand...


A good ground may be one of the most important parts of an electrical system. Many issues can be traced back to a poor grounding system.
 
Well, I got me a nice new Optima. Bought it off Ebay..........and it came to me from Amazon. I'm having a hard time keeping up with these things.
 
My stock cable from 6v Batt to Solenoid was #1. I keep it after converting to 12v. My ground goes directly to one of the two bolts on the starter motor, which was converted to 12v; cranks-over great even at -10 degree (I use 10w-30). Then two grounds engine to both body and frame.
 
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