YM2000 - alternator

sls · Nov 14, 2005

Checked the batt. w/ a new digital multi-meter and the batt. check 12.8-13.0 dc. Started the tractor and checked at 1800 rpms and it read 16.0 dc. Is this ok or is the volt. regulator not working? Thought it should read around 14.0 but not really sure.

Thanks for the help.

elarson · Nov 14, 2005

16 volts is a bit high, but it might be because the battery just delivered the power to crank over the engine. Give it a few minutes and see if the voltage hasn't come down to something more reasonable. I wouldn't think that 16 volts for a short time would damage the battery. The Yanmar mechanical regulator doesn't seem like the most precise piece of equipment, and I think that others have posted about it's strange operation.

Mickey_Fx · Nov 14, 2005

Your voltage is OK for the battery at rest S/B 12.7v. Personally I wouldn't be happy with a charge voltage of 16.

Don't know anything about your model tractor so don't have anything specific to offer.

California · Nov 14, 2005

</font><font color="blue" class="small">( Checked the batt. w/ a new digital multi-meter and the batt. check 12.8-13.0 dc. Started the tractor and checked at 1800 rpms and it read 16.0 dc. Is this ok or is the volt. regulator not working? Thought it should read around 14.0 )</font>

Relax. I think this is an application of a rocket-science diagnostic tool (new digital multi-meter) where the mfr expected the user to judge alternator output by watching a test lamp glow brighter when rpm increases.

That battery voltage is right on, so whatever charges it seems to have worked correctly for the past 25 years.

Welcome!

sls · Nov 14, 2005

Just replaced the batt. and didn't know if the higher voltage would damage it. The original battery would not hold a charge and looked to be very old. I replaced the battery and cables.

I asked my tractor dealer and he said that volt. output differs from tractor to tractor. Was going to buy a new voltage reg and he said not to waste my money.

normde2001 · Nov 15, 2005

According to the YM240, (YM2000), service manual there is an adjusting screw in the voltage regulator for adjusting the voltage output, (Lefty-loosey=less output). There is only 1 screw there, with a locknut, however I have not tried this adjustment.

Soundguy · Nov 15, 2005

If the voltage doesn't drop off from 16v real fast..after a few minutes of charge.. i wouldn't like it. You don't see much over 14.7 on most systems. Try to get it down in that ballpark..

Soundguy

Mickey_Fx · Nov 15, 2005

Speaking as a former Engineer for a major Electronics Co. and someone that has studied LA batteries for a critical application, I would not be satisfied with a 16v charge voltage.

A 12v LA battery can rise to about 13.9v but anything higher than that will cause problems if battery is fully charged and source voltage is applied for extended periods. Auto's are a good example of cyclic charging and a typ charge voltage is about 14.25.

Again, I wouldn't be happy with a 16v source voltage but that's me.

sls · Nov 15, 2005

Have you ever heard of an adjust nut on a mechanical volt. reg.? If so, is it located under the cover? Just learning about this stuff and don't want to "mess it up" if it is working correctly.