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.
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