alternator killing battery

riveroadrat

Well-known Member
I have 2 tractors with alternators. One is a 3 wire and the other one is a 1 wire. Both of them kill the batteries after sitting for a while. I never had one with a generator that killed the batteries. Do you all with alternators have that same problem. i think I'm switching to generators.
 
How long are your tractors sitting without being cranked? I have tractors wired both ways, no problems. But I do have one that has sat since last November and the battery is dead in it since I haven?t used it in about 8 months, going to put battery charger on it this week
 

Bad or weak diodes in the alternator will kill the battery. On some alternators, there is a very small leakage current in the vr section. This leakage will run a battery down after 6 months of non use. Have alt checked for bad diodes or shorts. Put a battery switch on it to stop the problem..Put a battery switch/cutoff on it to stop the problem.. Some batteries will self discharge over time as well. A dirty battery top can cause leakage, and simply washing the top of the battery clean can stop it. Improper wiring can also cause problems. A battery cutoff switch can fix this.

OR as a lot of farmers do.... disconnect one of the battery cables when not in use.
 
Install a quality battery disconnect switch, or slip off a battery cable when the machine isn't needed for more than a few days.

It took me a while to come around to that way of thinking, but once you do it, you will be AMAZED at how long a disconnected battery can stay charged. Just say'in!
 
Just some friendly advice, when posting it is always good practice to put the topic, i.e., tractor models, you are referencing, in your subject line if not in the text content as well so we all know what page you're on. In my opinion, you have something askew with your entire wiring system altogether, not the alternators fault, but the issue is causing it to fail. 12V jobs using a front mount distributor and a 6V coil need the external 1.0 OHM ceramic in-line resistor as well as the original OEM Ballast resistor in the circuit. If using a 12V coil, the external resistor is not needed. If you had a round-can cutout circuit, 9N after s/n 12500 to 1947 2N models, or with the 8N model, a voltage regulator in the original OEM circuit, they should have been removed when the generator was replaced with the alternator. Start a root cause problem solving method. 99.98% of all non-starting/non-running/electrical issues are due to poor/bad/incorrect wiring jobs regardless whether 6V/POS GRN or 12V/NEG GRN. Three things are required: FUEL FLOW; SPARK; and COMPRESSION. Problems almost always are one of the first two.

EXTERNAL IN-LINE 1.0 OHM CERAMIC RESISTOR REQUIRED WITH 6V COIL/FRONT MOUNT DISTRIBUTOR:
XRLi3vSh.jpg

ORIGINAL FORD BALLAST RESISTOR ? AN ABSOLUTE EITHER WITH 6V OR 12V COIL:
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Tim Daley(MI)
 
do you have the diodes on your alternator. if you don't it will back feed from your battery and drain it.
 
I bought a tractor while back. guy put a new battery in it. the old tractor was 6 volt positive ground when it came out. sometime or another there had been an delco alternator put on it. he hooked the new battery up with positive ground. battery ran down. switched cables and works fine now
 

Its always nice to make sure it does not have a drain on the battery. Its also nice to know if the charging system is putting out the correct voltage, something like a slipping belt on the alternator will now fully charge the bat it will live in a undercharged state till it just dies are does not have the guts to crank the engine over.

The first thing I would do is check the voltage running and make sure the alt belt is tight enough I can not turn the alt fan with my hand.

I do like battery disconnects even then the charging system needs to be up to par...

http://forums.yesterdaystractors.com/viewtopic.php?t=1267046&highlight=battery

I also have a solar charger on all my tractors but one I use that one all the time so far so good... The others set for months so take them off line with a disconnect and hook up a solar charger..
 
are you sure it is alternator causing problem because some years ago I had problem with battery going flat on our
JD 2040 if it was standing for more than a few days and the problem was faulty starter solenoid
 
When I got my 1550 the original alternator was replaced with a Delco SI. There was a continuous 5 milliamp drain. One terminal from the internal regulator was jumpered to the output terminal which was correct. The wire from the idiot light was connected to the output terminal, too. WRONG. That wire should have gone to the other regulator terminal.
 
The internal diode in your alternators could be bad.

The three wire needs an external diode as well. The one wire doesn't need an external diode.

The simple test for your alternators. Is to simply unplug the two wire pig tail one the three alternator. One the one site unhook the one wire. Let them sit and see if the batteries go down.
 
The purpose of a diode, lamp, or resistor in a Delco alternator from #1 excite pin to on/off switch is to prevent the engine from continuing to run when the switch is turned off.
 
I can leave mine sit for several months with alternators hooked up.

How long are you letting them sit, and how old are the batteries.

There is no need for disconnect, if all is working.
 
I have measured the drain on known good/working alternators (10SI) and it is close to 0.75 milliamperes or 750 microamperes & theoretically that would require about 2 years to drain the battery. Of course, most batteries will self discharge, connected to nothing by then. So, when folks nail the alternator as the bad guy on a dead battery, I say the either the alternator is bad or wired wrong, not that a perfectly well functioning alternator is the culprit.
 
No need to disconnect the battery when not in use, but highly advisable to invest in a Battery Tender float charger, not a trickle charger, to keep a full charge on it plus preserve and extend the life of it.

Tim Daley(MI)
 
Both are 4 banger 4000 diesel. One has been rewired by PO, has new battery, solenoid not wired in, I have gator clips on it for use. I tried to see a spark by touching battery cable to post but i think the drain is too small. The other one is all factory wiring, not used much, but if I use it enough its not a problem. I dont know if it has diodes, I know the older delco's you could see them right on the backside. I never had problems with a generator system.
 
(quoted from post at 09:55:04 07/04/18) Both are 4 banger 4000 diesel. One has been rewired by PO, has new battery, solenoid not wired in, I have gator clips on it for use. I tried to see a spark by touching battery cable to post but i think the drain is too small. The other one is all factory wiring, not used much, but if I use it enough its not a problem. I dont know if it has diodes, I know the older delco's you could see them right on the backside. I never had problems with a generator system.
imply insert a milliammeter in between cable end and battery post and measure the drain.
 

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