Tractor 1 wire alternator discharge?

riveroadrat · Jan 3, 2018

Does anyone know if a 1 wire alternator will discharge the battery if not wired correctly? Mine has a single wire coming from alternator to battery. There is another wire going from output post over to a plugin that is some sort of jumper plug. I dont know if that plugin is the problem or not. If I disconnect one of the battery cables and touch it to post I dont see a spark but it may be a very low draw. Any ideas?

JMOR · Jan 3, 2018

Wired correctly or incorrectly, they have a drain, but it is very, very small (micro-amps to low milli-amps), so it should require many months to drain a 'good' battery. Incorrect wiring could make for a larger drain, such as swapping blade terminals 1 & 2. Also, all those VRs inside the alt are not the same.

Royse · Jan 3, 2018

I like to use the three wires on mine, but drain isn't the reason.
I bought a 2N about 8 years ago that had a one wire already installed.
A single wire to the battery, or to the battery side of the starter
switch, was all it had too.
I didn't bother to change it and it never drained the battery.
There is always a small drain involved, but it always started without issue.

It was my main snowplow tractor for many of those years.

JMOR · Jan 3, 2018

Just to emphasize the point, the 10SI, even as a GM factory original 3-wire has that small drain. Drain is larger on some of the 1-wire but not by much.

riveroadrat · Jan 4, 2018

I didnt know they had a small drain. I may just wire it with the plug and see if that does it. As long as i keep using it, it has no problem, after about 2 weeks it is down to about 10 volts.

Bob · Jan 4, 2018

Installing a good battery disconnect switch on machines that sit unused a lot is not a bad idea.

You'll be surprised the difference it makes in battery power after they sit unused for even up to a year.

pomester · Jan 4, 2018

a bad diode(s) within the alternator can cause the battery to drain - there are several youtube videos/articles you can access by searching for 'alternator diode drain' or similar - there are simple tests that can be performed to identify this condition if you have even an inexpensive multi-meter -

a battery disconnect switch will alleviate the symptoms, but I've found those switches to be fairly expensive and not very durable if used on a frequent basis, plus if you forget to throw the switch you often end up with a fully drained battery, always inconvenient and shortening battery life - tho not necessarily a bad option on an infrequently used piece of equipment -

David

RDobbs · Jan 4, 2018

I have a one wire alt on my old Allis. Forgot how I wired it
but do know that I have to rev it to 2000 RPMS each time I crank
it in order that the alt is excited and begins to charge.

jr1983 · Jan 4, 2018

New one wires do not require exciter rpm. That said I've had better luck with a three wire

Eman85 · Jan 4, 2018

Easy thing to do is use a digital VOM that measures amperage. Disconnect the neg cable and hook it inline and measure amperage flow. Should be 30 milliamps or less. Best way is to use a battery disconnect and after you shut tractor off hook the meter leads across the disconnect and then open the disconnect.
A one wire alt usually doesn't have that extra jumper wire, just 1 wire to the output terminal. A 3 wire setup uses that jumper and then the other wire triggers the alt when you start it. On a retrofit you have to install a light or a diode inline to prevent backfeed into the ign if you wire one with the 3 wires.

Tractor 1 wire alternator discharge?

riveroadrat

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JMOR

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Royse

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JMOR

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riveroadrat

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Bob

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pomester

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RDobbs

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jr1983

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Eman85

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