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Battery cable size

A

Anonymous-0

Well-known Member
what is the best cable size for the 6 volt battery set up on the farmall M. Iwant the cable to be large enough to supply power to the starter at a rate that it will work good.
 
Mkirsch is right. We have used 1 guage on our Ford model A, which is a 6 volt, and it also seemed to work fine( cranking, charging etc.).
 
This would be a time that Hugh MacKay would chime in with the 0 or 00 cables. The biggest that you can get from a truck repair shop.
 

#1 will do just fine. If you want to pay the price difference, you can go to #0 or even #00. Shoot, you could move clear up to #0000, but that ol' M won't start any better than it will with #1.
 
On most old 6 volt tractor applications (Especially for larger such as Farmall M or John Deere A etc) I recommend AT LEAST 0 WHILE OO IS EVEN BETTER...........

When you only have 6.3 volts to begin with and heavy current draw can reduce battery voltage even further YOU CANT AFFORD TO BE DROPPING TOO MANY VOLTS ACROSS THE CABLE, the starter motor needs all it can get and the heat energy (I squared R losses) wasted and dissipATED ACROSS A TOO SMALL CABLE does NOT help matters.

Sure, 1 or 2 gauge will work and not do as much harm when its warm BUT let the temp drop to zero and the battery efficiency drops plus the engine is hard to crank OUCH you will be wishing you had 0 or 00 gauge cables

John T
 
(quoted from post at 08:18:32 01/27/11) On most old 6 volt tractor applications (Especially for larger such as Farmall M or John Deere A etc) I recommend AT LEAST 0 WHILE OO IS EVEN BETTER...........

When you only have 6.3 volts to begin with and heavy current draw can reduce battery voltage even further YOU CANT AFFORD TO BE DROPPING TOO MANY VOLTS ACROSS THE CABLE, the starter motor needs all it can get and the heat energy (I squared R losses) wasted and dissipATED ACROSS A TOO SMALL CABLE does NOT help matters.

Sure, 1 or 2 gauge will work and not do as much harm when its warm BUT let the temp drop to zero and the battery efficiency drops plus the engine is hard to crank OUCH you will be wishing you had 0 or 00 gauge cables

John T
Click to expand...

I won't argue, but the length of the cable adds into the equation also, and the Farmall H and M tractors all have fairly SHORT battery cables.
 
I found this site that was kind of neat.
http://www.powerstream.com/Wire_Size.htm

I figured 2' cables and 40 amp draw. I had a tough time finding the draw so it may vary from that greatly.
00 - .013 v
0 - .016 v
1 - .02 v
I am not sure your starter will ever notice the difference.

Let's have some fun. Lets figure on crazy long 10' cables.
00 - .064 v
0 - .081 v
1 - .102 v
Things start to change there. The drop is almost double, but you would still need a pertty good MM to pick it up.

I'm not an electrical person, so please correct this data if I am way off.
 
(quoted from post at 09:58:17 01/27/11) I found this site that was kind of neat.
http://www.powerstream.com/Wire_Size.htm

I figured 2' cables and 40 amp draw. I had a tough time finding the draw so it may vary from that greatly.
00 - .013 v
0 - .016 v
1 - .02 v
I am not sure your starter will ever notice the difference.

Let's have some fun. Lets figure on crazy long 10' cables.
00 - .064 v
0 - .081 v
1 - .102 v
Things start to change there. The drop is almost double, but you would still need a pertty good MM to pick it up.

I'm not an electrical person, so please correct this data if I am way off.
Click to expand...

Yes, that's what I am talking about. With a 2 foot to 3 foot long cable, the #1 gauge wire should be sufficient, but the #0 or #00 sure won't hurt anything.
 
Like the others say, as big as you can: #0 minimum; #00 preferred.

Alternatively you can run 2 smaller size cables (AWG #1 or #2) in parallel. It's not "original" - but it will accomplish the same thing.
 
I just looked in a book I have one automotive electrical systems. Granted they are for 12 volts systems but this will be in the ball park. It says for a 4 cylinder auto starter any thing over 110amp is to many amps so yep what you say about 40 amps is 1000% correct and with 6 volts that draw might be up as high as 200 amps and that in turn mend big cables.
Also just to add more of what it said 200 amps for a 6 cylinder and 250amps for a V-8 GM auto
 
325 amps is an expected initial draw on 6v cranking an M. More is possible with a shaved head, and/or big domed pistons. Cold weather both increases the amps, and decreases the battery output. 550 Cold crank amps (CCA) is reasonable for a 4 cyl car engine at 12v. so cables are very important. 0 or 00 gauge as noted below. Jim
 
Gene isn't 1 gauge just at the edge of being to small for a 6 volt M?? Wouldn't 0 or 00 be better. I in no way am trying to hurt or harm by this question
 
(quoted from post at 10:49:43 01/27/11) I just looked in a book I have one automotive electrical systems. Granted they are for 12 volts systems but this will be in the ball park. It says for a 4 cylinder auto starter any thing over 110amp is to many amps so yep what you say about 40 amps is 1000% correct and with 6 volts that draw might be up as high as 200 amps and that in turn mend big cables.
Also just to add more of what it said 200 amps for a 6 cylinder and 250amps for a V-8 GM auto
Click to expand...

I thought 40 was low, too. The only stuff I could find in my breif web search was that normal tractor starters were 20A for 12v and 40A for 6v. The same source said that the initial draw was far more, but once it was spinning it was 40A.

BTW, I agree that bigger is better I just wondered what this magic voltage drop came out to be. It is time to go eat, but I will play with that little calculator after supper.
 
Any M on 6 volt in the middle of the winter is gonna be a pain. Thats a big engine with lots of compression and 6v is just to light for it. Practically every M around here has been switched to 12 v,and starts great anytime of the year!! Heavier cables and a good battery will help, and on an H will work great,but i would never trust an M anywhere from home with a 6 volt system!! just my 2 cents..
 
Most Ms in my area were converted to 12 volts back in fiftys. In fiftys we still used 12 volt generators instead of altenators. I think John Deere As and Gs came from factory on 12 volts in fiftys, I know they had 2 6 volt batterys but not sure if they were in series oe paralell.
 
(quoted from post at 18:46:21 01/27/11) Most Ms in my area were converted to 12 volts back in fiftys. In fiftys we still used 12 volt generators instead of altenators. I think John Deere As and Gs came from factory on 12 volts in fiftys, I know they had 2 6 volt batterys but not sure if they were in series oe paralell.
Click to expand...
I know one stage newer and they were in series. I doubt they would take a step backwards after the letter series. They were still using 2 12s in series on the 4440s.
 
Size 00 with soldered lugs and run the ground to a starter to frame bolt and that is about the best you can do. I also use those external teeth washers between the starter frame and the cable for a good electrical connection as they bit into both metals. As others have said if you are in a very cold area you may find a 12 volt conversion better suited with less issues. What I described works find on the H and smaller tractors on 6 volt systems. Good luck, Hal.
 
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