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66' charging question

1609 Views 12 Replies 4 Participants Last post by  albatross
I know there is a thread on this from several years back, but I'm wondering if there is any new info...

Is there any easy way of checking to see if the system is charging or not?

I put a new battery in it a couple years back and it just seems like it slowly drained the battery until now I have to put it on a charger all the time.

At this point I'm sure I need a new battery but before I put one in I like to have a good idea if the charging system will maintain it.

thanks TD
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Tony welcome to WFM. It is not unusual for the small garden tractor batteries to die every couple of years. When I worked for JD in the 1970s the RF batteries only had a 90 day replacement warranty. Here are a couple of tests. With the ground cable removed from the battery and the switch in the off position touch a test light to the negative post on the battery and to the ground cable or just to the frame. The light should not light up. If it does you have something that is staying on with the switch off that will drain the battery. Lots of possibilities for that including a bad voltage regulator or a shorted wire. A second test with the battery all hooked and the switch and engine off test how many volts the battery has. It should be close to 12.5 volts but 12 volts is acceptable most of the time. Now start the engine and with the engine at 1/2 throttle or above test between the battery posts again. You should now get a reading of 13.5 to 14 volts. If it stays same as the first reading either generator or voltage regulator is bad. I have one more test but try those first. Roger
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Battery maintainers are cheaper than batteries and can keep a lawn and garden battery alive in a tractor that doesn't get used much for many years. I have recently put up several of the solar chargers on my barn that has no power to keep tractor batteries and my camper battery charged during off season. They are working nicely. Sometimes even on one with a properly charging generator they can drain during unused periods.
Roger, with tractor not running battery is at 12 volts, when I check it while tractor is running w/throttle above halfway I get no change in voltage, it stays at 12.

I didn't have much time when I checked this so I wasn't able let it run for very long to see if the voltage would start to drop on the battery.

Also I did not find any kind of battery drain with the first test you suggested.

Jason, I do plan on replacing the battery as soon as I get things figured out and I think I will use your suggestion as well..

If it doesn't go up the generator isn't charging. The next test is to hook a jumper wire to the field terminal of the generator. With the engine running and the VOM meter connected to the battery terminals touch the other end of jumper wire to the positive battery positive post. The voltage should come up. If the voltage goes up the voltage regulator is suspect. If it doesn't the starter generator is suspect. Be very careful with any of these test that you DO NOT short the wires out. What you are doing is by passing the VR. That will give you a place to look for the problem. It could be still another problem like just a bad wire or wire connection. It could also be the brushes in the generator. Usually the next question I get is how can the generator still start the engine. That is because it is really a starter and generator all in one unit and does 2 separate things. Roger
Roger, Cant you also remove the wire from the field post on the S/G and put a meter on that post, start the engine and see if there is any output from the generator? Might be a little safer than taking a chance of shorting something.

As an FYI, I had these symptoms on my 66 and it ended up being the armature.
Bill the reason you do it the way I described is by putting 12 volts to the field the generator will go to maximum charge. There is nothing I know of to measure the field terminal for. There is only input to that terminal. The armature post would be what you would measure for output and since he said the voltage doesn't change between running and non running the generator isn't producing output. By jumping the field you can decide if it is a voltage regulator or generator problem. I agree it is a bit dangerous to do especially on a RF tractor. That is why I didn't recommend doing it in my first post for tests. Also you don't want to have the field terminal getting 12 volts more than a short time. Roger
Roger, I did the test jumping the field terminal.

When I did that my meter did jump to 14 volts across the battery

So if I understand you, it sounds like the gen is working so my problem is in the regulator? Or could it possibly be the ignition switch?

Not the switch but more likely the regulator. If it not the VR then it a problem in the wiring. At this point I would vote for the VR. You really have to take the battery area of the tractor apart to replace the VR. Make sure the VR is grounded well. Make sure there is some bare metal where it bolts on to the battery case. Roger
Jump starting your tractor with a vehicle could be the culprit for the bad voltage regulator. Glad to hear it wasn't the generator. Like Roger said, the battery box needs to come out for replacement. Be able to get good look at wiring at that time.
Tony, thanks for starting this thread. I went to start up my 67 112H this morning and everything was fine and then all of a sudden the generator light came on. I checked voltage at battery and it was only about 12.4v with engine running. Was about to do Roger's tip of jumping from field post to battery when I noticed that the wire was broken at the VR. I am sure I would have found it but if not for this recent thread and Roger;s tip it probably would have taken me longer.
Thanks for all the input guys, I'm going to tear into this, this weekend double check all the wiring and connections and go from there.

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