Electrical question - dead battery

[HDMan]

I have a question about my 1947 Cub which has been converted to 12V and has the electric start. I just got the tractor, and the previous owner connected the battery before we drove it, and before we picked it up. I asked why, and he stated it was a habit. Well, I think this may have been more of a habit.

2 days in a row, after driving it, my battery was dead. I charged it, ran the tractor, next day the battery was dead. The battery was almost 7 years old, so I replaced it yesterday (it was already charged). Today, it was dead. Any ideas?

Here is some more data. When I would drive the tractor, the amp meter would be just above zero, but if I jumped the unit to start it, the amp meter would be way over to the right (+). On a fresh battery, it would start out running with amp meter to the right, then it would settle back down towards just above middle. To me, an electrical engineer, that would seem right. When I put the new battery in, I suspected a draw somewhere, so I connected the (-) and tapped the cable to the (+) to see if there was a spark, and there wasn't, or at least not that I could see.

Any ideas on what it may be or what to look for?

HDMan

[Bigdog]

Do you have an alternator or generator? You need to take some voltage readings to see what is going on. If the 12 volt conversion was done correctly, the system should be charging somewhere around 14 volts. If all they did was stick in a 12 volt battery into a 6 volt system it is probably not charging correctly if at all. If it still has a voltage regulator or cutout, it probably has burned points which are sticking and causing the battery to drain back through the system when not running. If you can give us a little more information we'll try to figure it out.

[HDMan]

How do you tell on the unit if it has a generator or an aternator? My guess, and it is only a guess, is that based on the detail put into the restoration, it was done as a full 12V conversion. Where would I find the regulator or cut-out that you talk about and where would I find these points?

I have some football coaching and some town meetings the next few evenings, so it will be Thursday before I get at it. I will charge the battery, then run it and get voltage measurement at the battery. It should go somewhere above 13V if it was done correctly, I would assume. Let me know how to get you the right data and I sure will do it!!! Thanks for replying!!

HDMan

[Bigdog]

If it's an alternator, it will be internally regulated. A generator will have an external regulator (square / rectangular box) Look up under the hood at the right front just behind the radiator. You will see the drive belts. Describe the unit. A generator will be a long cylinder about 5 - 6" in diameter and about 8" to 10" long, solid case. An alternator will be shorter, bigger around and generally the housing is very open for air circulation.

[HDMan]

It is definitely an alternator as it is a short, larger diameter unit almost like what is on a car. Would this then have an internal regulator and then would I need to replace the unit, or is there still points somehwere I need to be concerned about?

Again, I will put the unit on charge tonight and hopefully tomorrow night I will take the voltage readings.

HDMan

[Bigdog]

An alternator will have internal regulation. Take some readings and we'll go from there. If you can, take a look at the connections and tell us how many wires you see connected to the alternator. There are different configurations and this will have some bearing on where the leakage current is coming from.
I suspect your battery is draining back through the alternator and the previous owner knew that and that is why he removed the battery cable when not using the tractor.

[HDMan]

Will do BigDog!!! I will take readings, maybe even a picture or 2 and I should have the data in a few days!! Thanks again, you guys are an unbelievable help!!!

HDMan

[HDMan]

OK, I charged my NEW battery to a full charge of 13.63 volts which I measured once I removed the charger. I connected the battery to the tractor on the NEGATIVE only and hooked a meter between the POSITIVE post and the POSITIVE cable. I found a 10.8mA draw with NOTHING turned on, not even the ignition switch.

I then connected the cable and ran the tractor. I then measured the voltage at the battery and I was getting 13.95 volts. From what I am reading, the alternator is charging the battery, however SOMETHING is drawing a slight load which is draining my battery within about 30 hours. As a newbie tractor owner, I would take off the hood and ingition switch/light switch/ammeter housing and start disconnecting items until the draw went to zero. Now this will take some time, so I am hoping somebody has been down this path and says, yep, that 10.8mA draw is your ____________ (Please fill in the blank).

Thanks again!!!!!!

HDMan

[allenlook]

It's your...

Stereo?

[Dale51]

OK, I charged my NEW battery to a full charge of 13.63 volts which I measured once I removed the charger. I connected the battery to the tractor on the NEGATIVE only and hooked a meter between the POSITIVE post and the POSITIVE cable. I found a 10.8mA draw with NOTHING turned on, not even the ignition switch.

I then connected the cable and ran the tractor. I then measured the voltage at the battery and I was getting 13.95 volts. From what I am reading, the alternator is charging the battery, however SOMETHING is drawing a slight load which is draining my battery within about 30 hours. As a newbie tractor owner, I would take off the hood and ignition switch/light switch/ammeter housing and start disconnecting items until the draw went to zero. Now this will take some time, so I am hoping somebody has been down this path and says, yep, that 10.8mA draw is your ____________ (Please fill in the blank).

Thanks again!!!!!!

HDMan

The Alt. is either wired wrong or 1 of the diodes is bad.

[Bigdog]

HDman - you know what you have to do. You're right, just disconnect one circuit at a time and see where the current drain is occuring. I suspect you'll find the problem in the charge circuit. Perhaps a blocking diode breaking down and allowing current flow. The first thing I would disconnect is the output line from the alternator.

[Dale51]

http://albums.photo.epson.com/j/AlbumIn ... 065733&f=0

chech uot this & find out if it is wired right

[HDMan]

Any idea which drawing would be closest? This is a 1947 Farmall Cub with a 12V Alternator conversion.

HDMan

[Dale51]

Any way you can post a pic as this would help greatly

[Bigdog]

Is it a 1 wire alternator or a 3 wire alternator?