The alternator on my case is only putting out 12.2V. After using the tractor all day, the next day I have start issues. Check the battery and voltage is 12.1 or 12.2 and just won't crank the engine. After charging the battery, it fires right up. So, is this alternator toast or is there anything I should do to see if I can get the output up to 14.2 volts?? Thanks, Ron
Batteries that are good will crank an engine at 12.2 volts. You can have that voltage but not the amps. Check the battery voltage while cranking the engine over. The reading at the alternator you are getting is battery voltage, not charge voltage.
You get up too early, or stay up too late Vetech? If it's only got 12.2V running and starts fine after you put a charger on it, then your alternator is the issue. Typically an alternator will have three or more wires connected to the back of it. The biggest one is connected to the battery + directly, all the time. One of the smaller ones will supply +voltage from the ignition switch, through a warning light in the instrument cluster sometimes, to the voltage. If the alternator doesn't get this voltage, because the warning light is burned out or whatever other reason, then the alternator won't charge. You can check the wires for voltage when the engine is running, or take the alternator off and have it tested. Don't worry about your batteries yet.
I noticed that the positive alternator line only runs to the positive terminal of the starter. Should that be changed and removed from the starter and routed back to the battery???
No, that part is correct. I meant that the alternator is connected to the battery all the time, hooking it to the starter terminal keeps that connection away from the battery, so it's safer from damage. What I should have said is check the wires on the back of the alternator for voltage with the key ON, but the engine off. The key should send +voltage/power to one of the small wires with the key on. There will be +voltage to the big one all the time, but you need to find out if the alternator is getting that voltage signal to start up from the key switch, if not, figure out why not. Do you have a red idiot light in the shape of a battery? that should light up with the key on, but without starting the engine, does it?
Yes, the red idiot lights up with the key on. Thanks for the clarification. Ron
Yeah, I misread the post. I’m blaming that last beer I had.
Regulator?? Cheap and super easy to change on the back of the alternator. New brushes come with it. Good PM. Should look like this... https://www.ebay.com/itm/VOLTAGE-RE...750929?hash=item3f6fb01751:g:nPgAAOSwux5YMejG
Update: I purchased the voltage regulator off ebay. Pulled the old one out and the brushes were worn down about half way. Installed the new brushes and checked voltage output. Got the same value of 12.3V. Anything else I could do to see about getting that voltage up around 13.5V without buying a new alternator? Thanks, Ron
Does the light stay on after it is running?? First change out the battery dash bulb, just to be sure, it is part of the exciter circuit for the alternator and needs to be good. Confirm that the alternator case has a good ground. You should have power at the exciter terminal (blue wire in diagram) with the key on, not running. If you think the exciter wire circuit may be faulty, make up a similar wire with bulb and install like the diagram to bypass the original wire. Now while running, check the charge terminal (red wire) for voltage. This can be done with the terminal disconnected from the alternator to prevent seeing the battery voltage. Only connect and disconnect wires when not running, key off, use tape to insulate loose wire ends to prevent shorts.
you can just put 12volts to the D+ terminal. If the alternator starts charging then you have an issue with that circuit. It uses to filament of the bulb to provide voltage to excite the field. Very small amount of current flows. The light will light up if there is a ground at the D+ terminal. Easiest way to check that light circuit is to bypass it. Jump 12V to the D+ and see what happens. If it does not charge your alternator is the issue.