1 Wire Alternator

[Traditional Farmer]

So when did you check MY tractors? If you didn't you have NO idea.Come on by with your meter.

 

[JMOR]

(quoted from post at 17:07:28 01/25/23) So when did you check MY tractors? If you didn't you have NO idea.Come on by with your meter.

have measured many, both 3 wire and one wire and ALL have a parasitic drain. You very clearly have not measured or you would have knowledge of same. You would be able to tell me the drain current measured value. Can't do, can you?

 

[Traditional Farmer]

All I need to know is mine won't run the battery down from Oct to May,must not be much of a drain.As you may have noticed some here say they don't some say they do,as with everything else all apparently not created equal.Have you actually run and used a tractor with a 1 wire alternator in the last 10 years?

 

[Dieseltech]

I wonder if the later one wire systems have changed from the earlier regulators? I used two different test lights today between the bat ground cable and the negative post. My older test light showed no light glowing at all, which SHOULD mean no current draw down over time. My new Snap On EECT400R test light DID show a small current draw, and confirms why I remove the ground cable if tractor won't be used for awhile. The last three one wire alts I got since 2016, and I like how well they work.

 

[docmirror]

Single wire alt: Will charge from idle because it has a voltage path to energize the field. A 3 wire will only charge from idle after the batt voltage exceeds to bias voltage in the regulator and energizes the field. That's why sometimes one needs to rev the engine slightly to get the regulator to engage on an ext regulated 3 wire alt.

Batt drain at rest. First - depends on how the 1 wire alt is wired into the tractor. If it is direct from the charge line to the plus of the battery yes there will be a very slight leakage current backward through the four rectifier diodes onboard the alt. I don't know what the leakage current is for those diodes but it is pretty small. Maybe 50 to 100 microamps? Just a guess.

If the 1 wire is routed through an ignition switch it will have a hot position and a start position. Some tractors only have off and hot. In that case there will be no leakage because when the ignition switch is off, there is no current path from the diodes on the alt to the batt + term.

The best way to do it is to wire the 1 wire alt lead to a 50 amp relay, and then to the plus term of the batt. Run the hot lead from the batt through the ign switch so it will pick or engage the relay AFTER the tractor starts. This requires a 3 pos ignition switch which does not lend itself to some tractor designs with a safety push switch to start.

3 wire alternators are suitable for conditions where there is a large amp draw that is far from the battery, and also far from the alternator. The sense wire on the alt is used to sense the voltage drop of the loads at the battery and adjust the output of the onboard regulator in the alternator to compensate for that voltage drop, and provide a hotter voltage AT the batt + term. In our case on most vintage tractors the elect loads are rarely large, and rarely far from the alt or batt, so the sense wire is not needed, and the default energy from the alt is enough to maintain the batt charge voltage without the distance sense circuit.

This post was edited by docmirror on 01/25/2023 at 08:41 pm.

 

[Janicholson]

Rationale: not all one wires are the same. I have seen one wires that clearly pulled 1/2 amp when not turning (through the output to the battery). Those took 2000 rpm on the alt pulley to self start. I have seen some that were at 120ma draw and would take a long time to lower a battery so far that starting failed, maybe a month, depending on the battery size and condition. I recently put a 3 wire 10SI from O'reilly on a 56 IH Pickup. I started it up without the excite wire or sense wire attached to check the belt alignment and it charged immediately. I called the store and the manager said they sell only one in that amp size and sell it as either a one wire or 3 wire. I hooked up the dash warning light, and the sense wire and it worked as intended. so my take is that everybody is correct!!! Measure the draw. Jim

 

[Traditional Farmer]

Maybe that is it,most of mine are pretty new.I had a 1 wire on a Landini I bought it was an old alternator and it would run down the battery in a hurry.Also have seen some so called converted ones they don't work very well.Also I think maybe an electrical system will have some other draw on it and the alternator gets the blame.The DB 780 I bought with a tree across the fuel tank crushed it and the dash.Took everything off beat out the hood and put on a plastic fuel tank.Complete electrical system is the battery cables and a wire about 4ft long running from the Alt to the starter solenoid.(LOL)Great little raking tractor for the last 20+ years

 

[JMOR]

(quoted from post at 08:16:57 01/26/23) Maybe that is it,most of mine are pretty new.I had a 1 wire on a Landini I bought it was an old alternator and it would run down the battery in a hurry.Also have seen some so called converted ones they don't work very well.Also I think maybe an electrical system will have some other draw on it and the alternator gets the blame.The DB 780 I bought with a tree across the fuel tank crushed it and the dash.Took everything off beat out the hood and put on a plastic fuel tank.Complete electrical system is the battery cables and a wire about 4ft long running from the Alt to the starter solenoid.(LOL)Great little raking tractor for the last 20+ years

"Maybe that is it..."
" and no battery drain."

Many words could have been saved!