Bad alternators or am I frying them?

[BarnyardEngineering]

This one should be right up John T's alley:

On my Dad's W-400, we converted it to 12V with a Delco 10SI alternator.

Rather than run new wires, I connected the original GEN wire to the BAT terminal on the alternator. At the regulator, I moved the GEN wire over to the BAT terminal. I took my excite wire off the coil, using a diode. The F terminal wire is taped off up at the alternator. This leaves everything unmolested and easily restored to original.

The setup works great, for a while. Twice now, the alternator regulators have failed causing the alternator to go to full charge. I just put a THIRD alternator on this tractor, and it's working as expected again, for now.

Looking at the internal schematic of a voltage regulator, the L and BAT terminals are directly connected, so I'm using the regulator as a bus bar.

This could just be bad luck. The first two alternators I bought were the cheapest remans you could get from Advance Auto Parts. The alternator I put on this time is supposedly a better quality.

 

[Roy Suomi]

I have had great results using the Delco 1 wire set-up. Wire thru an ampmeter direct to starter big terminal. No external regulators
needed. Tape up the wires and forget about them. Once the tractor is running, goose the throttle to get the alternator to start charging.
When you shut off the engine, the alternator will not draw any current. We are negative ground, aren't we ?

 

[old]

Any time I do a 12 volt swap I go with new wires since I have no idea the condition of the old wires. All it takes is a bad wire that short out once in a while to smoke things

 

[John T]

Mornin Barnyard, here's my thoughts:

1) On the old VR its BAT terminal is what got to the battery to charge it, often via a series ammeter so
the wire that used to attach to BAT on the VR should wire to the alternators big main output stud HOWEVER
I usually upgrade that wire to at least 10 Gauge.

2) Its ONLY 4 terminal VR's (BAT ARM FLD LOAD) that have the 4th extra LOAD terminal which feeds loads
like lights and ignition......On 3 terminal VR's (BAT ARM FLD) those loads are instead fed from the Load
(NOT battery supply) side of the ammeter.

3) The LOAD on 4 terminal VR's (while sure it feeds battery voltage) is NOT quite the same as the BAT
terminal. The LOAD is used so the genny can feed loads voltage without them passing through relay contacts
and in theory its supposed to provide better regulation.

4) Even if it works I would NOT use the old VR like a buss bar but instead transfer loads like lights and
ignition up to the LOAD (NOT battery supply) side of the ammeter.

THAT BEING SAID I still cant say for sure or know if that matters and is whats hurting your alternators.
On the Delco 10SI family the small 2F terminal (1R is excitation) is for voltage sensing and many people
just jump wire it down to the big main output stud and that works HOWEVER if wired instead to the battery
thats a better location as far as battery voltage but Ive never had problems using 2F to the output..

While incorrect voltage sensing (location or how its wire and if right) can harm an alternator (sees low
voltage so it cranks up) I dont know how if and where your 10SI is wired so dont know your problem

DISCLAIMER Im more into genny and VR systems and electrical power than electronics so see what the more
electronic minded gents here have to say as Im NOT any alternator expert. The ONLY things I have to offer
is insure the alternators 2F is wired correct to sense voltage (may harm alternator otherwise), you did
swap to NEG ground I trust, and dont use the VR as a buss bar, wire loads to ammeter instead

John T

 

[JMOR]

Well, if you keep blowing alternators, maybe a "guess" beats nothing. Perhaps the VR winding #3 is being over-current-ed by an alternator output that is very likely many times higher than original generator output for which the VR was designed, resulting in insulation failure??? I realize that #3 sees only ign, lighting, etc. and not battery charging current, but still something to consider, when all else fails.

 

[BarnyardEngineering]

Thanks John T. I was looking for your expertise on generators and VRs, something along the lines of "oh, if you put voltage to the whatever terminal, that causes such and such to short to ground and that could be causing your alternator failures."

The condition of the wiring harness is quite good. It appears to have been replaced with a modern replacement wiring harness (i.e. colored plastic insulation not cloth). Even if OEM was colored plastic insulation it would be brittle and cracking by now. This harness is still quite flexible.

I just don't want to have to tear the tractor half apart to run one stupid wire. That's what it would take. There is no access to the back of the instrument panel due to the fuel tank. The panel only comes out about an inch when you unscrew it.

 

[BarnyardEngineering]

(quoted from post at 08:43:47 11/04/22) I have had great results using the Delco 1 wire set-up. Wire thru an ampmeter direct to starter big terminal. No external regulators
needed. Tape up the wires and forget about them. Once the tractor is running, goose the throttle to get the alternator to start charging.
When you shut off the engine, the alternator will not draw any current. We are negative ground, aren't we ?

My luck with one-wire alternators is not good. More often than not they run the battery down. Take it back, they put it on their little machine, nothing wrong with it, no warranty replacement.

Never had a battery run down on a 3-wire.

Yes, negative ground.

 

[old]

I have only one tractor with a 1 wire and it doesn't run the battery down but it also is a 50/50 chance it will charge the battery

 

[JMOR]

(quoted from post at 13:20:30 11/04/22)

(quoted from post at 08:43:47 11/04/22) I have had great results using the Delco 1 wire set-up. Wire thru an ampmeter direct to starter big terminal. No external regulators
needed. Tape up the wires and forget about them. Once the tractor is running, goose the throttle to get the alternator to start charging.
When you shut off the engine, the alternator will not draw any current. We are negative ground, aren't we ?

My luck with one-wire alternators is not good. More often than not they run the battery down. Take it back, they put it on their little machine, nothing wrong with it, no warranty replacement.

Never had a battery run down on a 3-wire.

Yes, negative ground.

For all those who have complained about their batteries draining after tractor sits un-used for a week or so, the content of Mr. J.A. Nicholson's post over on the Farmall board, may explain the problem. I have measured that 'standby' drain on several 3-wire set-ups. NOTE: both 3 wire and 1 wire always have a continuous drain whether ignition is on or off!

Jim says, "The internal VR in some of the one wire systems draws about 200ma (if measured across an open battery terminal) others draw more like 500ma or more."

Whereas, my measurements for 3-wire show 0.75ma.

Best case then is 200/0.75=267X worse AND worst case is 500/0.75=667X worse drain.

Knowing that you can't extract every last amp-hour out of a battery, for sake of this discussion let us assume that we can. Real life results won't be this good, by some margin. Further more, if you did extract every last A-H, then there would be zero left to operate a starter.

Start with a 75amp-hour full charged battery. Apply the 3-wire 0.75ma drain.

75A-H divided by 0.75ma=100,000 hours. Divided by 24hr/day, yields 4,167 days (or 11 years). We all know that most batteries sitting on a shelf connected to nothing won't last that long. So what this says to me is that the 0.75ma drain is reasonably insignificant.

BUT, look what happens when we apply the 267X worse or the 667X worse 1-wire 'standby' drains: the 4,167 days divided by 267=15 days.***

Even worse, 4,167 divided by 667=6 days.*****

I have personally measured the 'standby' drain on a 1-wire set-up, D22ac-1 internal reg, and it was 1.8mA, but have no other reason to doubt Mr. Nicholson. So, it seems reasonable then that a dead battery after a few days might very well be related to a 1-wire alternator, if his numbers hold.. Measured D22AC-1, 1.8mA drain, or 2.4 X the GM 3 wire 0.75Ma drain..4.6 years vs 11 years

Rather than speculation or even testimonials, such as 'mine doesn't discharge that fast', I would like to see a good hand full of 'standby' drain current measurements made & posted by anyone able to perform same.

No doubt, all 1-wire regulators are not born equal.

It could be that when & where those high 'standby' drains are encountered, that the regulator is just plain faulty and really has nothing to do with 1-wire vs 3-wire. However, speculation, testimonials are not the answer, just some real current measurements.

I hope we see some measurements!
One final note, Modern vehicles have computers and some have a 25mA drain all the time, but even those calculate out to 0.75/25 X 11 = 4 months.

 

[John T]

The only and simple way to wire a one wire (as you already know) to the battery to charge it typically by
connecting it to the LOAD side of the ammeter with big enough wire. While that same LOAD side is where
lights and ignition need connected Id prefer them up to the ammeter (if practical) even if sure the
alternators output is basically the same place electrically..... Not many wrong ways to wire a one wire but
hey alternators are NOT my cup of tea and many here are sharper on them. Maybe a battery problem or a short
is contributing to alternator failures ?????? Be nice to have a working ammeter to see what current its
delivering plus a volt meter to insure correct charging voltage maybe 13 to 14+ !!!

John T Just mowed LAST time cleaned mower, changed oil, added Sta Bil, parked it safe away inside the
garage yayyyyyyyy

 

[Janicholson]

Use the BAT terminal of the VR for a junction, not through the L terminals internal winding. Make sure the Arm Terminal is taped up on the VR. I think your original plan was OK, but still passes current through the regulator. Jim

 

[M-MAN]

I would suggest cleaning your
battery ground and if it isn't ran
to the starter or engine block move
it there.

I've only had repeated alternator
failures once and a bad ground
caused it. There was paint on the
block where the wire attached.
Cranked fine but alternators didn't
last.

 

[Geo-TH,In]

I cooked 3 new alternators, all with a lifetime warranty from
Auto Zone. Don't jump start a dead battery. The 60 Delco
alternator can't take a joke. If you don't believe me read the
directions. Before I installed the 3rd alternator I read the
Instructions which said to fully charge the battery. I did and
no more frying alternators.