sudden meltdown

[Wayne]

I took my battery in for testing because it doesn't hold a charge for long. But it never has, so that is not a new problem. They tested it and said they needed to charge it in order to do a load test, which they did. Everything fine. I took it home, hooked it up and when I was hooking it up it sparked like I was hooking it up backward, but I wasn't. I started her up, walked to the mailbox, came back and drove 5 feet before it died. Heard a funny noise under the seat and found the negative terminal had melted off.

Well now what? It was hooked up correctly, so I'm guessing there must be a major short. I'm terrible at electrical diagnosis. I checked the main wires but saw nothing askew. I'm afraid to put in a new battery, and there is nobody around here who works on Cubs. 8 inches of snow prediucted for tonight, and my Cub is my plow....

Needless to say....


HELP. And dumb it down, I flunked electricity class.

[Wayne]

one more hint: I thought I saw a bit of smoke and a burning scent near the front end of the carburetor, but there's really nothing there to burn. It dissipated quickly so I couldn't find the source.

[zippy1]

What model tractor?
And did it work for you before? Did you replace or reroute any wires?

[R Bedell]

Well, there must be a good sized short somewhere. Do you have a DVM or a VOM and know how to use them? If not, I would check to see some discoloration in some electrical components, ie: the S/G. Look also, at. the battery cables to see if some insulation has rubbed through.

[Wayne]

Oh sorry, it's a 108. Thought it was in my sig file, where I will go put it now.

I have a multitester and know just enough to be dangerous. I don't know if it's a VOM or a DVM, but I do know its not a DVD or VCR.

I will look at the components again in the daylight. Is it possible the battery shorted internally? I kind of stumbled when I was carrying it and it took a bit of a jarr. I also forgot it was on trickle charge and left it on for several days...

I can't imagine how a short strong enough to cause the kind of sparks I saw when I hooked up the battery could have developed in the tractor when it was just sitting there. No mice are living in it that I know of. I'm clinging to the hope this is just a battery problem.

[cubfixer]

Try this: Using the voltmeter (VOM) or digital volt meter (DVM), with the key off, measure the resistance between the two battery cables (with the battery out of the circuit). It should be infinite ohms. If it is zero ohms, then you have a dead short, which will smoke your battery. Look for a wire shorted to ground somewhere (possibly the positive battery cable rubbing somewhere against the frame or other sheet metal). When you turn the key to the run position, you should get zero ohms possibly to the points being closed. Turn the engine by hand and see if the short opens up. This may be OK. I don't know what the regulator will do to your reading. Just look (or smell) for smoked or crispy wires. Could be the battery, but I doubt it. You will need a new battery, so when you hook it up, look for hot or smoking wires with the key off, and then turn the key on (but do not crank the engine until you are sure the wires remain cool). The battery should not spark when you put the battery in with the key off. If it does, you have a dead short, which will have to be fixed before you attach the battery terminals wires.

Good luck!!

[Wayne]

I get 0 ohms with they key off, so I guess I have a short. I haven't traced the entire
hot cable yet, but I did notice some melted wire leading to my headlights. However it isn't melted through, so I don't think that is the source of the short, and I rarely have them on. I also notice a short section 3/8" of exposed wire leading from my coil to the left front end of the engine, where there is a little rectangular box with a push button on it. I don't know what that box is but I'm sure you do. Anyway that exposed wire was not melted, and it isn't the source of the short I'm getting with the VOM because it isn't touching the frame. I suppose it's close enough that it might arc, and it is in the general vicinity of where I saw smoke when the battery croaked. But I think I'll have to keep looking for why I have a dead short with the key off and that wire not touching anything.

With the key on, I haven't been able to get anything but zero ohms even after turning the engine pulley several times.

[R Bedell]

I suppose it's close enough that it might arc

12VDC will not jump to make an arc.

To melt a battery terminal, it must be a heavy short. Disconnect the S/G wires and see if the short goes away...??? Disconnect other items until such time there is no reading on your VOM.

[cubfixer]

If you have zero ohms with the key off AND the key on, You probably have a direct short to ground from the battery positive wire. I like Roland's suggestion to take the wires loose at the S/G, and see if that changes anything. Also, pull the wire from the Battery terminal on the regulator. See if that helps. If your light wires smoked, are they on an switch? Remove the wire from the ammeter to the light switch (I am assuming that this is the way your cub is wired, but you know what assume does for you...). Eventually, you will get to the point that there are infinite ohms between the battery cables. Then you can figure out where the problem lies.

When I put in a new voltage regulator that was different from the original regulator, I hooked the Load terminal to ground. Talk about a smoked wire! It doesn't take much to ruin your day!

[Wayne]

I'm sorry...S/G?