PT 1850 Alternator replaced

SpringHollow · Jun 7, 2008

I have been having problems with my alternator for over a year (maybe since i bought it but I think it started a month or 2 later). The voltages have been 15.5 - 16.5 V. Boiled my battery and popped a vent plug after having shut down the PT and had the engine cover open for maintenance. Fortunately, i was turned and getting a tool when the acid sprayed all the way up to my floor joists above. Turned the wood black.

The high voltages started blowing fuses, etc. So, I removed the alternator and took it to an alternator shop. They said it was fine. I replaced teh voltage regulator any ways and reinstalled it. Still high voltages. Took it back out and jumpered wires to the battery, etc. looking for a bad connection but nothing worked. Replaced battery cables etc since they were easy to do but no go. Talked to terry and tried everything he sugested. Since it was winter by then, i had to keep using the PT to plow. It would die after an hour or so because the dash breaker would blow.

Now that summer is here, i called Terry again at PT. I told him i was just going to replace the alternator since even if another shop said it was good, it was about the only reasonably easy thing to try. $275 later, i had a rebuilt alternator from Deutz. Installed it Friday. I get 14.7 V when no lights, etc are on but 14.2 V when there is any load. So, I think it is working.

The reason I am mentioning this is that Terry said he has seen the same problem a couple of times (I believe his alternators tested out fine as well) but replacing the alternator solved the problem. So something to think about if you see something similar.

The new alternator is very different. The voltage regulator seems built into the alternator rather than a unit you snap in. Also, the electrical connections are in different locations. By rotating the alternator, i was able to make the battery cable reach.

At some point, i will upload pictures of the new alternator.

Ken

ponytug · Jun 9, 2008

Dear Ken,

I hope that this fixes your problem. When I have seen high voltages frying batteries and electronics, my first suspect is the regulator. A close second is a poor set of grounds, often intermittant grounding. You might want to check and clean your ground, just in case. It will help keep from frying your voltage regulator as well, which are easily disturbed and killed by an intermittant ground.

All the best,

Peter

ldabe · Jun 9, 2008

My PT 422 would not start, just click.
The negative battery cable attached to the engine was the culprit, it was loose.

Tightened it up, and everything was fine.

Grounds can cause a lot of different problems (or should I say loose or no grounds).

SpringHollow · Jun 9, 2008

Thanks Peter and Idabe. I cleaned all of the connections, replaced all of the ground cables, ran one from the front of the tractor also, jumpered every connection on the alternator with new wire, disconnected lots of the other wires on the tractor, new voltage regulator - none of it made any difference. Fortunately, it looks like the new alternator solved the problem although 14.2 V is still a little high. But much better than 16.5 V!

Ken

woodlandfarms · Jun 10, 2008

Ken, just to double check. Have you put a digital meter in place of your needle meter? I assume so as you are so accurate but if not it could be your meter giving you the 14.2 reading and the alternator is running at 13.5

Carl

ponytug · Jun 10, 2008

Ummm... 14.2-14.5V is the target voltage for charging. The target is 13.8V continuous charge at the battery terminals. A fully charged lead acid battery should top out around 12.8 at full charge.

Many voltage regulators have a high initial phase to charge up after the starting load, dropping to a lower voltage over time.

Your normal, running load, should be very low, and after 15-20 minutes I would expect to be reading close to 13.8 at the battery.

All the best,

Peter

P.S. More information at Lead-acid battery - Wikipedia, the free encyclopedia

ksimolo said:
Thanks Peter and Idabe. I cleaned all of the connections, replaced all of the ground cables, ran one from the front of the tractor also, jumpered every connection on the alternator with new wire, disconnected lots of the other wires on the tractor, new voltage regulator - none of it made any difference. Fortunately, it looks like the new alternator solved the problem although 14.2 V is still a little high. But much better than 16.5 V!

Ken

SpringHollow · Jun 10, 2008

Hi Carl & Peter,

Yes, that was with a digital multimeter. It was still putting out 14.2 V with lights on after 15 minutes but i did not run it much longer than that. I will see what it does the next time i use it for any length of time.

Ken

cqaigy2 · Jun 11, 2008

14.2 sounds right to me.

BobRip · Jun 12, 2008

cqaigy2 said:
14.2 sounds right to me.

Sounds good to me. I used to have a Rambler with it set to 13.8 and it would not keep the battery charged. This was a design flaw and not adjustable. Every three months or so the battery would run down. If I cleaned the contacts it would be OK for another 3 months. I eventually added a diode in the ground of the regulator. This raised it to about 14.5. It never ran down again, but I had to add water a couple times a year. Believe me this was a big improvement. In other words, 14.2 is really good.