Wire size for 24 volt starter system

I received my new 24 volt starter today that I will use in the 720 D and I was wondering what gauge wire I should be using?

This was a pony motor tractor originally so it has no wiring for a 24 volt system. I do have all the original JD mounting brackets from an original JD 720 electric start. Also in the starter kit came a LIT-200 12-24 parallel switch.

I am not electrically inclined, so I have no idea how this parallel switch works, so can someone explain this to me. When I push the starter button, does everything switch automatically internal in the switch? How does it know which battery to charge. Also where do I connect my amp meter?

I don't have a generator , but plan on getting a one wire alternator.

A simple wiring diagram would also help. Nothing came with the starter or switch.

On a 24 volt system one can get by with smaller battery cables like the common #2 used for cars and trucks.

Glad you are squared away.

As discussed, smaller cable is fine, but I would probably go with a #1 on that.

I've recently been working on a genuine from-the-factory 24 volt electric start 730 diesel with four 6 V batteries. All the battery cables are 2/0.

Are you planning to set it up as "original" with the 24 volt stuff floating with respect to tractor chassis? May be an interesting challenge to use an alternator!

Being not electrically inclined, I'd suggest finding someone local who is electrically inclined to give you first hand help. As others have said concerning the 24 volt system, it can be tough trying to help remotely through a medium such as a YT forum

The original 24 volt systems didn't have an ammeter.

Where are you located?

I like welding cable. Even though it?s big it?s easy to work with and bend. I buy the ends in an auto electric shop and solder them.

I am in upstate NY. I am not trying to be original with the tractor to restore it. I just want a wiring plan that is simple to build and understand for starting the 24V starter motor and charging the two 12v batteries. Nothing more. The only other electrical item is the fuel gage.

If the originals didn't have an amp meter, how did you know you were charging?

Eventually you will be wishing that you sent the starting engine long block out for a rebuild and used it instead.
I see sparks, melted insulation and dead batterie sin your future. And a pull chain for starting in cold weather.

The original 12/24 system had an idiot light for charging indicator but you won't be able to have one of those if you insist on a one wire alternator. The three wire alternator can be wired for an idiot light indicator and you can add an ammeter to either system as you like.

Yes, everything switches automatically when you press the starter button and when you let off it too. At that time then both batteries are then re-connected in parallel to charge at 12 volts.

I'm in favor of the welding cable comment, bigger is better with the ground going to a starter mounting bolt too.

<image src="http://photos.yesterdaystractors.com/gallery/uptest/a273059.jpg"/>

There are a couple of jumpers used on the relay above, these can be made of flattened copper pipe perhaps two or more together to ensure amperage capacity is only limited by what the batteries can generate internally. These two jumpers are at terminal E to C and another one at terminals A to F. Battery A should be thought of as the system power source while Battery B is to never be used except for this relay and the starter cable source. So the ammeter would be connected to terminal E or C for - ammeter terminal and the alternator for + ammeter terminal ( I think ). Not a problem if it indicates discharge instead of charge, just reverse the leads on the ammeter to show a charge.

Internally, for running/charging terminal A is connected to B terminal while C is connected to D and E is NOT connected to F. Press the starter button and A-B connection opens up, C-D connection opens up, while E-F connection is made. H terminal is the starter button which also needs to go to the starter solenoid to activate it at the same time as this relay. Terminal G can be grounded to terminal B. Power to the starter comes from terminal D which is also always connected to positive post of Battery B.

Above diagram shamelessly stolen from
<a href="http://www.texasindustrialelectric.com/T_114_12_series_parallel_switch.asp target="_blank">T_114_12 Series Parallel Switch</a> site for further study.

Can't find your relay number which has me worried a little, except it came with a starter for use with that starter, we can only hope it's a capable and similar series/parallel relay and not a cheap 200 amp ripoff. The one shown above is rated for 1500 amps with call us for pricing. The lack of a diagram is another source of worry, best of luck.