Battery cables for 6v. starter w/12v. battery

BoatBuoy

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I’m trying to put a 1956 30hp Johnson back into service. The old wiring was brittle and unusable so I’m having to fabricate a new harness. Since the starter is 6 volt and I’ll be using a 12 volt battery, what gauge wire should I use for the battery cables?<br /><br />BTW, I'm aware of possible problems w/6v. solenoid and mercury safety switch.
 
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DJ

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Re: Battery cables for 6v. starter w/12v. battery

Are you sure it is 6 Volt?
 

BoatBuoy

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Re: Battery cables for 6v. starter w/12v. battery

Yep, verified by starter shop.
 
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DJ

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Re: Battery cables for 6v. starter w/12v. battery

That's a new one on me.<br /><br />I do know that 6V cables need to be heavier. A couple sizes larger (in guage) should be OK. That always worked for 6V cars/trucks.
 

Paul Moir

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Re: Battery cables for 6v. starter w/12v. battery

I would be tempted to actually undersize the battery cables with the intention of dropping the voltage at the starter a bit. Have them act like a resistor.<br /><br />But I've never tried that before. I think the 6v cables were #1 or #2, and the 12v cables were mostly #4 or #6 depending on year & length.
 
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DJ

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Re: Battery cables for 6v. starter w/12v. battery

Paul,<br /><br />I hear what you're saying. But, resistance makes heat. 6V's can create allot of amps.<br /><br />If it truly is a 6V starter, it should handle all that is available. It will only use what it needs.
 

tommays

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Re: Battery cables for 6v. starter w/12v. battery

Why not just but a 6 volt battery ? i cant see that starter being very happy running 12 volts :( <br /><br /><br />tommays
 

BoatBuoy

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Re: Battery cables for 6v. starter w/12v. battery

Originally posted by tommays:<br /> Why not just but a 6 volt battery ?
1. Ever toot a 12v. horn w/ a 6v. battery? Or turn on a 12v. depthfinder?<br /><br />2. Motor has no generator/alternator. Not sure what would happen if I needed a “jump” from other 12v. vehicle.<br /><br />3. Available/choices of 6v. batteries is not the best.(try to find a 6v. marine battery)<br /><br />4. Usually end up having to swap batteries around among various vehicles.<br /><br />5. Old timers tell me they always used 12v. on 6v. motors. Just don’t sit on it too long at a time.
 

Dunaruna

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Re: Battery cables for 6v. starter w/12v. battery

Originally posted by BoatBuoy:<br />
<br />3. Available/choices of 6v. batteries is not the best.(try to find a 6v. marine battery)<br /><br />
2 x 6volt deeps connected in series for the toys, pull 6volts off one of them for the starter. readily available.
 

jlinder

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Re: Battery cables for 6v. starter w/12v. battery

12 volt to a 6 volt starter? I know you say old timers say this is OK, but that sounds really wrong.<br /><br />Anyone out there (old-timer I guess) who can comment?
 

BoatBuoy

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Re: Battery cables for 6v. starter w/12v. battery

I can't believe outboards are that much different. The guy at the starter/generator shop told me to only crank 10-15 seconds at a time and let it cool a few seconds in between. Unless engine has a problem, this should be enough.<br /><br />VW's : "Most folks leave the 6V starter in place and run it on 12V. It will survive this for a surprisingly long time if you keep the duration of cranking short."<br /><br />Tractors : "The existing 6-volt starter not only can be reused but most often is your only option. It is improbable that you will be able to locate a 12-volt starter that will match your drive gears and mounts. Still, real caution must be used to avoid burning out your starter. The starter will get hot under 12-volt use so you should avoid cranking for long periods and let it rest between attempts. Keep your tractor tuned up and this should not be a problem."<br /><br />Chevy's : "In most cases you will not have to change the starter. If a starting solenoid is used to engage the starter, it will need to be changed. If the starter is in poor condition with worn bushings and brushes, the upgrade to 12 volt may hasten it’s failure. In most cases it improves starting."<br /><br />Trucks : "The starter is perhaps the easiest of the lot, it will survive quite nicely on a diet of 12 volts. Believe it or not, 6 volt starters are designed to handle a bundle more current than their 12 volt counterparts."
 
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