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12Volt battery cable on 6volt system

Started by JohnWNY, June 03, 2019, 09:55:43 PM

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JohnWNY

Has anyone used 12 volt battery cables on a 6 volt battery for better starting?  I have a 1939 LaSalle.

LaSalle5019

It will definitely crank much slower with 12 volt cables since they are a larger numerical gauge which corresponds to a smaller diameter wire size. You want 1-0 or larger diameter wire.
Scott

TJ Hopland

I'm no expert on the subject but I would think '12v' cables would just make things worse.   Reason is typically higher voltage means less amps for the same amount of work so assuming all else the same it takes less amps to spin a 12v starter.  Amps is what determines the cable size, more amps means you need thicker wire.   If the wire is too thin it gets hot that is wasted power that isn't going to the starter plus makes the resistance go up which takes more amps.  If this goes on too long something is going to give in a melted metal sort of way. 

So because of this 12v cables will typically be smaller than 6v cables especially the more modern you get because of the saving money and weight thing. 

If you are not concerned about an all original look I would get as fat of cables as is practical.   You can often buy fairly universal fairly heavy duty cables fairly cheap from places that specialize in heavy trucks and equipment.   Some of the farm and fleet sorts of places are often a good source.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Abe Lugo

My wife had this issue on here ‘33 Plymouth. Slow cranking.

I measured the cables needed. Went down to Napa auto and found 00 sized cables. I bought the proper lengths and ends, proceeded to make new cables. 
We also changed a the battery out to an Optima 6 volt gel battery.  Now it cranks like a 12 volt!

From what I have read you may not want to get the fattest cables but the next size smaller should work also.  We used the 00 because we had the Optima.  But if you  have a conventional battery. It may pull too much amps while cranking and not allow the coil to get power. I happen to read that someplace, so test it out.

One think to note new cables(original size) will still be better than old crusty cables. 
Abe Lugo  CLC#31763  Sunny Los Angeles,CA @abelugo IG

39LaSalleDriver

Here's what I measured and put on my 39 LaSalle:

Description: 45 in, 2/0 ga SGT Black, std 3/8 lug , std 3/8 lug

Description: 55 in, 2/0 ga SGT Black, neg top post term , std 3/8 lug

I had them made up by custombatterycables.com and have been very pleased with them. I had extra length put into the negative cable because I was running it to an additional stud I mounted into the commutator endplate of my starter. Oh, and I also run an Optima 6v battery too.
Jon Isaacson

1939 LaSalle 5019

Jay Friedman

My advice, for all reasons mentioned above, is to not use thin 12v battery cables on a 6v car like your '39 LaSalle.  My 6v '49 has a thick OEM Delco positive cable.  Like Jon's, my negative cable runs to a stud I installed on the commutator endplate of my starter.  I use a conventional Interstate 6v Group 2 battery, but like Abe's the motor starts as if it's being turned by 12 volts.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Steve Rinaldo

I agree with the above. The best cable to use is 00 welding cable used on the old buzz box welders. It is very fine wire and flexible. You can get this at any welding supply store. Steve

39LaSalleDriver

Quote from: Steve Rinaldo on June 04, 2019, 07:28:49 AM
I agree with the above. The best cable to use is 00 welding cable used on the old buzz box welders. It is very fine wire and flexible. You can get this at any welding supply store. Steve

I did some reading and studying on this. While a lot of folks use welding cable with success I'm sure, I encountered information that suggested it was not ideal for use as battery cables. Main reason being that the insulation on welding cables is fairly soft and not overly resistant to oil and such. I have found this to be true as the cables that came with my car were welding cables which had broken down with the insulation separating from the wires. To me they felt very "mushy" and potentially unreliable. On the 39 LaSalles they run under the car where they are exposed to a lot of crud, and in my case, some degree of oil flying loose from the rear main seal and draft tube. So I guess I'm not saying don't use welding cables, but be aware that they may not be the best solution. With my circumstances, I felt it best to spend the extra money and get a larger gauge with oil resistant insulation which I couldn't get with standard welding cables.
Jon Isaacson

1939 LaSalle 5019

Caddy Wizard

Quote from: USNTar on June 03, 2019, 11:54:35 PM
Here's what I measured and put on my 39 LaSalle:

Description: 45 in, 2/0 ga SGT Black, std 3/8 lug , std 3/8 lug

Description: 55 in, 2/0 ga SGT Black, neg top post term , std 3/8 lug

I had them made up by custombatterycables.com and have been very pleased with them. I had extra length put into the negative cable because I was running it to an additional stud I mounted into the commutator endplate of my starter. Oh, and I also run an Optima 6v battery too.


That sounds about right for a 6v Cadillac.  Better than welding cables.  Much, much better than 12v cables from the corner parts store...
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

JohnWNY


fishnjim

What thing of "better starting" are you trying to fix?   
There's more to starting than just speed of turning over the crank.   If should fire right off, if it's all correct.  Hand cranks worked.   Cranking until the oil pressure comes up should be enough to get gas to the carb.   Low compression, poor; electrical, plugs, dist, timing off, fuel ratio, etc. retard starting.

V=IR, so half the volts, doubles the amps.   Cable diam determines ampacity.   
So 12 V cables - smaller diam - are in the wrong direction and would heat up if cranked very long.   Hotter the cable, the higher the resistance, so it's a double negative.   
Bad hearsay at best.





LaSalle5019

I purchased my cable from Rhode Island Wire along with the battery and lug terminals and made up my own.  Correct gauge, good insulation and period correct.  Costs a bit more but I wanted the right stuff on my '39 LaSalle.
Scott

bcroe

Quote from: Abe Lugo
From what I have read you may not want to get the fattest cables but the next size smaller should work also.  We used the 00 because we had the Optima.  But if you  have a conventional battery. It may pull too much amps while cranking and not allow the coil to get power. I happen to read that someplace, so test it out. 

THAT has to be an old wives tale.  Bruce Roe