Battery wire size (gauge)

[save_old_iron]

See that little braided wire on the generator brush ?

Regardless of how big a welding cable you use or think you need to use to crank over the SG motor,

ALL THE CURRENT IN OR OUT OF THE SG HAS TO GO THRU 2 OF THOSE LITTLE BRAIDED WIRES.

If you do choose to hang a 4 gauge welding wire and terminal off the SG, as soon as the current flowing thru the starter wire passes thru the mounting stud on the SG housing, it must travel thru those little braided brush wires.

Just something to keep in perspective when arguing (or discussing) what size welding cable to start need to start a 10 Hp engine. Unless you are running a high compression engine and an automotive type starter to crank the high compression engine, 6 awg is more than enough to keep you out of the clutches of any "sexed - up" starter stories.

I'll take new and properly assembled 8 awg over poorly made or corroded 6 / 4awg any day of the week.

[PaulS]

Last evening I sat down and had a serious talk with that 2072 with the #2 battery cables. I said that if it did not behave and become an easy starter I would take the positive cable which runs the length of the machine and use it as a whip. The machine did not reply so I presume silence was concent. I was impressed with the flexibility of that big cable and know it was a little overkill but the price was really good and if it is good enough for a welder it is good enough for my cub(s). My son was able to borrow the crimping tool for the ends so the job was actually an easy one. I have no idea why the engineers placed the battery so far away from where the most power is needed.

[CADplans]

Originally Posted by save_old_iron

See that little braided wire on the generator brush ?

Regardless of how big a welding cable you use or think you need to use to crank over the SG motor,

ALL THE CURRENT IN OR OUT OF THE SG HAS TO GO THRU 2 OF THOSE LITTLE BRAIDED WIRES.

If you do choose to hang a 4 gauge welding wire and terminal off the SG, as soon as the current flowing thru the starter wire passes thru the mounting stud on the SG housing, it must travel thru those little braided brush wires.

Just something to keep in perspective when arguing (or discussing) what size welding cable to start need to start a 10 Hp engine. Unless you are running a high compression engine and an automotive type starter to crank the high compression engine, 6 awg is more than enough to keep you out of the clutches of any "sexed - up" starter stories.

I'll take new and properly assembled 8 awg over poorly made or corroded 6 / 4awg any day of the week.

That little wire is not the culprit, in most cases. That little wire is one of many culprits.

What you are trying to accomplish is getting voltage AND amperage to the starter.
EVERY wire will reduce the available voltage, EVERY foot (or inch) of length of wire has an effect.

First off, after too long of a winter, there is insufficient voltage at the battery. That 6awg wire you recommend will further reduce the voltage. The starter has to work with what gets there. AND the engine has been setting, it does not want to start in the first place.

Then take into account that the starter is 30-40 years old, EVERY volt and EVERY amp matter.

Then there is the battery, how many of us try to get an extra two months out of that battery?
During the last two months (typically the end of the mowing season!! ) that battery is low on voltage, and way down on amps. The heavy cable is gonna deliver a start, where a #6 cable will fail.

My #2 twenty foot long jumper cables will start the tractor right now, in cases where the #6 jumper cables fail. I hate the #2 jumpers - they are just too heavy.
BUT, they get the job done. ALL THE TIME.

In a perfect world, 6awg is fine. My world is less than perfect, ALWAYS!!

The heavy cable is the lowest cost insurance you can add to make sure that little wire in the pic gets every amp and volt possible.

[J-Mech]

I'm going to add to what CAD said. Yes, the wire on the brush is small, but if the S/G is in good working order it will only draw the amps it requires. It won't overload itself just because it is supplied with ability to do so. Think of it like a fluid system. At the end of the garden hose there is a sprinkler. Attach a 1/2" garden hose to it and it sprays. Attach a 1" garden hose to it and it sprays higher. The sprinkler doesn't blow apart with a bigger hose, just sprays "better". Electricity and fluid power are EXACTLY the same concept. If the little brush wire burns up, it's not because you supplied too much voltage/amperage to it, it's because the S/G was drawing more amps than it was made for. Either as a result of wear, or corrosion. Voltage is supplied, amps are drawn based on load.

[save_old_iron]

Before I add an additional reply / explanation of my view on this subject,

I would like a consensus on what the average amperage draw of the starter is believed to be during the cranking process. Let's go with the more common 10 - 12hp SG based Kolhers.

With an accepted amp draw thru the SG, I can do a "buy the numbers" dissection of why I believe wire gauge in that range is inconsequential and why I believe good integrity of the wiring and connectors FAR OUTWEIGHS any gain for a 2 step increase in wire gauge. The "buy the book" calculations will surprise and hopefully enlighten.

p.s. I can't offer the group a lifetime of Cub experience but I will base my statements on 40 years experience with electronics engineering in the medical field. Let's see how they compare in the real world.

[R Bedell]

Well, there are some variables to the application(s). But I would venture to say, the Delco-Remy S/G's draw somewhere 60-80 Amps DC. That seems to stick in my head from somewhere else.

[CADplans]

Originally Posted by save_old_iron

Before I add an additional reply / explanation of my view on this subject,

I would like a consensus on what the average amperage draw of the starter is believed to be during the cranking process. Let's go with the more common 10 - 12hp SG based Kolhers.

With an accepted amp draw thru the SG, I can do a "buy the numbers" dissection of why I believe wire gauge in that range is inconsequential and why I believe good integrity of the wiring and connectors FAR OUTWEIGHS any gain for a 2 step increase in wire gauge. The "buy the book" calculations will surprise and hopefully enlighten.

p.s. I can't offer the group a lifetime of Cub experience but I will base my statements on 40 years experience with electronics engineering in the medical field. Let's see how they compare in the real world.

Originally Posted by R Bedell

Well, there are some variables to the application(s). But I would venture to say, the Delco-Remy S/G's draw somewhere 60-80 Amps DC. That seems to stick in my head from somewhere else.

I would not doubt that number,

Even half that is still a lot.

Go back and look at that pic of the brush, and the wire size, WOW, the wire is small.

But, the wire is short, with DC electricity, length matters. Lengthen that wire to 3 feet, hit the starter, and watch the smoke fly.

Steel is a horrible conductor. To use it, you need LOTS of steel (the entire GT tractor frame) or a very short conduction path ( the screws on the S/G).

There is no answer that is perfect. Yes, S_O_I, the small wire will work, IF everything is perfect.

BUT, if you are gonna replace a 40+ year old wire, why not use the biggest that is reasonable, when the cost is almost the same?

Remember, some of us prefer our steel rusty, but, working!!



They can not all be trailer queens!!