case 540 voltage regulator

[maplesap]

discovered that the battery has been hooked up backwards and has been running negative ground. it has been like this for a while. what should be replaced to get this corrected? tractor runs fine but battery wont hold a charge...will need battery for sure.

 

[kevinthefixer]

Are you sure the battery is getting a charge to hold? If you still have a mechanical regulator on a generator it's possible all you need to do is switch the battery around again. If someone just installed the battery backwards the generator probably won't charge. If you've changed to an alternator you must stick with negative ground. If you do actually need a battery, and want to switch back to positive ground, you will need to polarize the generator: after installing the battery, jump from the battery minus to the generator armature post for one second and you're done. Make sure the ignition coil is wired right if it's coil-and-points ignition; plus side to points for a positive ground system.

 

[maplesap]

thanks for the reply Kevin! sort of undecided as how to proceed... there is an extra (third) wire coming from the generator to the voltage regulator housing, this doesn't show on any schematic. the tractor runs fine and the battery only lasts for about a year before it starts acting like it needs a charge. I would like to make this right but I am worried about opening a can of worms if I change anything. The voltage regulator mounting bolts don't want to budge nor do the screws at the terminals of the voltage regulator. Half tempted to let well enough alone but not completely comfortable with this approach.

 

[kevinthefixer]

If that extra wire just hooks to the generator case, it just means someone didn't trust the sheet metal/chassis/engine to properly ground the regulator, sometimes rust gets in between these components and won't let the juice through. I'm a believer in extra ground wires myself. Anyway I suggest you fire the tractor up and put a voltmeter on the battery, at idle you can figure you're not charging at all and just measuring the state-of-charge of the battery, then crank it up to 1500 rpm or so for a few minutes, voltage should slowly come up to 14 or 14.5 and level out. If it never comes up, or levels out at a lower voltage, you're not charging at all or not enough. If it goes higher it's overcharging and cooking the battery. I don't know the exact specs for your generator but it should be able to put out enough amperage to run all the factory lights with plenty to spare, so you should be able to hold 14 volts or so with all the lights running. If you can drive or trailer it to an auto parts store they will usually check battery/starter/generator/regulator for free in hopes they'll sell you something.