MF 1080 Alternator and Voltage Regulator

[BCMac]

Hey folks,

So the charging system on the MF 1080 I recently purchased doesn't charge the battery. I knew it going in, and the previous owner used the tractor sparingly and kept the battery topped up with some small solar panels. I would like to fix it properly.

It has a relatively new rebuilt alternator on it. But still doesnt charge. Previous owner figured it was probably the voltage regulator but since as I said it got used minimally, didn't bother to fix it. I have purchased the voltage regulator, but in going through my shop manual, it mentions there is some sort of fuse washer that can burn out and will cause the battery to stop charging. It says to check that first. In searching for a replacement, I can't find it. The only place I can seem to see it referenced at all is in the shop manual.



Anyone know of these? Also, any tips or tricks to replacing the voltage regulator?

 

[BCMac]

I swapped out the voltage regulator today, and it's helped, but its not quite there. Not running I sit at about 12.89-12.9v at the battery terminals. Where before it either didn't change or went down when running, now it creeps up, but only slightly - at running speed it gets up to about 13.0-13.1v.

Being as I think it should be up around 14v, I am guessing there is something else not right. What other things should I be looking for?

I was told the alternator was relatively new (couple of years) but I haven't tested to check. Is there an easy way to check the alternator is functioning as it should?

Could it be old corroded wires not passing enough juice through them?

Any thoughts as to where to troubleshoot is greatly appreciated.

 

[Kenneth S]

AGCO part number 513983M91 (Fuse Assembly) for alternator.

 

[BCMac]

Spectacular, thanks! I couldn't figure out that part number for anything. Perhaps I need more practice in the Agco parts book.

 

[Kenneth S]

On some parts you really have to look closely in the parts book, sometimes some parts aren't in the section that you would think it should be in. The fuse is listed in the electrical wiring section instead of the alternator section.

 

[BCMac]

It looks like I have managed to get this working...to a certain extent. With cleaning some terminals, swapping the regulator and such, it now gets up to just over 13.5v and the ammeter actually ticks to the upside for the first time in who knows how long.

Still, I feel like it should be up closer to 14v. Any thoughts as to where else I might be experiencing some leakage?

 

[Kenneth S]

It should charge in the 13.5 - 14.4 volt range. How old is the battery? Clean battery terminals? The + wire from the alternator in good shape (not corroded, or loose connections)? When the battery drops to less than 12 volts if it sits for awhile the battery is starting to go away. While the GM one wire, internal regulator alternator makes the wiring simple it's really better to also hook up a sensing wire from the one terminal on the alternator directly to the positive battery terminal on the battery so the alternator knows what voltage the battery is at (which could be why your only seeing 13.5 volts when it's charging). Here's something you should read it explains a lot Delco SI Alternator 1-Wire vs 3-Wire Explained.

 

[BCMac]

Batteries are just a year or two old. The terminals are pretty clean, but I will give them another once over. The battery cables are a bit tired and tattered in spots and could probably stand to be swapped out. I'll read that over. Thanks.

 

[Xfaxman]

Did you clean both ends of both battery cables?

Also check for voltage drop across the cables, they may be corroded under the insulation.