Alternator/battery question

[handirifle]

My MF1010 has been acting up a bit lately. I have noticed for a bit that the alternator light seemed to be coming on more than usual (as in not at all before).

Then the last couple days it wouldn't turn over(on starting), or turned over very slowly, and then the usual clatter of the starter not getting enough juice. Using the jumper portion of the batt charger starts it right up.

I finally got the battery out of today, it's a real PITA to get to, and I noticed that about 3 cells were dry or nearly so. I filled them up with distilled water, and put the 10 amp charger on it for 1 1/2hrs. I then tested it with my specific gravity tester, the ones with the squeeze bulb and it gives you a reading from each cell, and I got zero readings from any of the cells. Well, I was heading into town anyway, and took it to the batt shop and he tested it under load on his machine. says batt checked out OK.

I asked about the alternator and he said to start the tractor, and when it's running pull the red lead off the battery, and if it dies, the alternator is bad. i did that, and it kept running. So I figured the alternator is OK, and since he said the battery is OK, I should be good to go.

I started using the tractor, and sure enough, the light comes back on, and stays on till about 2000 rpm. So I am thinking next, the batt might not STILL be fully charged, so I just set it up with the 1.5 amp trickle charger, to maintain it overnight.

Does it sound like I am on the right track here? The belt for the alternator is still as tight as it's ever been, so it's not slipping. If the light comes back on, what would you suspect? It's been years since I looked, but I MIGHT have an alternator tester (shunt type), but am not sure.

Suggestions?

Thanks

 

[devildog1]

Get your multi meter out and check voltage of battery after charge , should read about 12.75 to 12.90 volts. Now start your tractor and check battery once again, should read about 13.35 to 13.55 volts.
DevilDog

 

[BigBoyinMS]

I know just enough to sound like I know something, sometimes.
First, taking the cable off while it was running probably didn't harm anything but you can damage a diode doing that.
Second, an alternator has to have a little current to start charging and it also has to have a bit of resistance in the charge circuit, such as a volt meter, ammeter, or "no charge" light for it to start charging at a low RPM. I don't know about all alternators but a standard Delco internal regulator alternator hooked up as a 1-wire alternator will not start to charge till you hit around 1600-1800 rpm. But the "no charge" circuit is working on yours. Sorta sounds like a diode may be bad. I would be getting the alternator tested.
And I'm really surprised the battery tested good after being dry in half the cells.

 

[sjb]

If your charge light is only coming on sometimes, and goes out when you speed up the engine, the first thing that I would check is the alternator brushes.


Stan

 

[handirifle]

OK so it seems like most suspect the alternator. I will see what the voltages measure.

If it does the same thing as before, I will pull the alternator next and get it checked.

I will post updates. Thanks for the feedback.

 

[Soundguy]

yep.. check the voltage.. if it ranges from sub 12.7 to 14.7 then the alt may eed help. might be bad slip rings.. etc..

soundguy

 

[handirifle]

Well the static voltage was 13.07 and when running was 12.47, so I will pull the alternator and have it looked at.

 

[Soundguy]

yep.. got some issue there.

I'm surprised static was soo high.. 12.6 is about nominal on a la battery like that, unless it just came off a charge.

in any case.. see what happens with the alt..

soundguy

 

[sandman2234]

Dumb question, but is the belt tight?
David from jax

On edit,

Opps, posted that in the original description... duhhh

 

[BeeferMan]

If the tractor is a diesel with a manual shutoff, it'll most likely keep running even if you pull off the battery cable...