Alternator is overcharging, need to rebuild it!!!

alia176 · Apr 2, 2016

Hey fellas,

My ALT is way overcharging the battery at nearly 15vdc!

Looks like the regulator is kaput. That explains the copious amount of corrosion on the terminals and on the hold down bar. In any case, I can easily rebuild it myself and need to buy a rebuild kit. Well wait a min, is it still under the 5 year warranty? Doesn't really matter a whole bunch but that thought just popped into my head.

Can anyone suggest a vendor for purchasing a rebuild kit from? My tractor has 85 hours on it so it's still a young buck

I suppose I can't just leave well enough alone and may even go for a higher output unit as there seems to be plenty of room in there. It's a 50 amp unit and I prefer to upsize the case for more output vs simply modifying the existing case for more output. Keeping these things cool is very important as you know. Anyone stuffed a larger output unit? I'd imagine we all have similar size engines so the available space should be similar as well.

Thank you.

oldpilgrim · Apr 2, 2016

alternators are supposed to put out about 14.5 volts.

The corrosion on the battery is due to a well known problem with the batteries that Mahindra used in many models, especially the xx16 series. The posts don't seal in the case and gases escape. Clean everything up and slob lots of grease around the post before you reinstall the terminals and all will be well.

SedonaDave · Apr 2, 2016

I completely agree with above post...a working 100% battery should have a voltage of 12.7 volts....The only way a battery can charge is when the incoming voltage is higher...So your good as gold!

So yes...clean, inspect, or replace any bad connections from battery to starter...and check all the grounds also..

alia176 · Apr 3, 2016

My apologies, I seemed to have created two threads by mistake and I need to delete this thread! Although, I'm not sure if I have the power to delete my own thread.

def38 · Mar 22, 2018

I just installed a new alternator on my M-F. Voltage output with a fully charged battery, engine at idle, is 14.2 volts. Your 15 VDC seems a bit high unless there is some load on the electrical system you are unaware of. Also, check the battery after it has been charging for awhile. Is it warm to the touch? Also, what is the OCV (open circuit voltage) of the battery when the ground cable is disconnected (engine NOT running)? I believe we need a bit more information before you know which part of the electrical system to condemn.

Many auto parts stores will test your alternator for free.

BTW, I used to travel through your town on the way to Tempe, AZ (ASU). That was before interstates. I travelled route 66.

dickfoster · Mar 22, 2018

alia176 said:
Hey fellas,

My ALT is way overcharging the battery at nearly 15vdc! Looks like the regulator is kaput. That explains the copious amount of corrosion on the terminals and on the hold down bar. In any case, I can easily rebuild it myself and need to buy a rebuild kit. Well wait a min, is it still under the 5 year warranty? Doesn't really matter a whole bunch but that thought just popped into my head.

Can anyone suggest a vendor for purchasing a rebuild kit from? My tractor has 85 hours on it so it's still a young buck I suppose I can't just leave well enough alone and may even go for a higher output unit as there seems to be plenty of room in there. It's a 50 amp unit and I prefer to upsize the case for more output vs simply modifying the existing case for more output. Keeping these things cool is very important as you know. Anyone stuffed a larger output unit? I'd imagine we all have similar size engines so the available space should be similar as well.

Thank you.

with only 85 hours I should think you have warranty coverage. I don't see the need for a high output alternator unless you somehow installed some kinda high amperage accessory like an electric winch.