Spark at + battery terminal

I have a TO 20 with starting woes. It is a + ground 6 volt tractor. I had a neighbor help me diagnose a no-crankinng problem
accompanied by a total discharge of a new battery. Clearly there is a short somewhere. He diagnosed the starter as the problem,
advised me to recharge the battery and then reconnect the + battery cable. I recharged the battery and then there was a big spark
when I tried to do reconnect; he said just connect and see if there is a subsequent battery drain to test the starter as the
problem.. The starter is not connected at the moment. I am hesitant to deal with the spark possibility again!

Any thoughts on possible cause? When I installed the new battery there was no sparking. I am better at mechanical stuff then
electrical, that's for sure.

Thanks in advance for any help.
 
Test the starter for a short. Get a multi meter, one that shows ohms (resistance/continuity). Put it on the ohms setting and put one probe on the top post of the starter and the other on a good ground (clean a spot). Should be zero or no continuity. If not zero, starter has short. Or you could test battery direct to starter (use jumper cables), tractor out of gear. But if there is a short you will get the big spark again. If not, i.e., if starter is ok, it will turn over and you will know starter is not the problem.
 
This might be stupid but its something I did before...
6 volt battery was so dead that I put charger on backwards. I had 12 volt in my mind,
And of course it reversed the polarity, then had a hell of
a time trying to figure out why such a big spark when trying
to hook battery cables back up..sometimes I really screw up.
 
Before you guess that the starter is bad, make sure all battery cable connections are clean, bright, and tight, especially where the ground cable contacts the tractor frame. For best reliability ground cable should connect to heavy metal of the frame as close to starter as possible, not to a thin metal battery holder.

Also your battery cables...they should be heavy cables with good clean post clamps. Old battery cables can have corrosion in the cables that is hidden by the outer coating of the cable.

As to the sparking problem, check that the cut-out contacts in the generator regulator are not stuck together.
 
An ohm check from starter power input post to ground should show very low ohm reading because there is continuity through all the windings to ground. This test will show if a winding is open (high or infinite resistance), but will not tell if it is shorted (very low to zero resistance)since low resistance is normal
 
The starter should have nothing to do with the cable sparking when connected unless the starter contactor is closed, as in welded together, or mechanically held together. If either case were true, the engine should have began to try to turn over when the cable was connected.

More likely there is a drain through the generator cut out relay.

Try recharging the battery, disconnect the generator cut out relay, and the starter, try it again. If it still sparks, there is still a drain. A lot can be told by the size of the spark.

If it is a major pop, with the wiring heating up, there is a short to ground. Try to trace the wire that is getting hot, but don't leave the battery connected too long, it can damage the wiring. Look for a pinched wire, a wire touching ground where the insulation has fallen off, mouse chewing, etc.

If it is a minor spark, something is on, drawing a small current. Any spark at all will drain the battery. Look for an accessory left on, like the lights, or ignition switch on. Start disconnecting wires until you find the wire that kills the spark. Also look for green corrosion under the dash, around the amp meter, back of the ignition switch.

If disconnecting the generator stops the spark, try reconnecting the generator. If the spark comes back, replace the cut out relay.

If disconnecting the starter stops the spark, find out why there is power to the starter. Should not be power to the starter unless you are trying to start it.

Be careful working with this, be aware something is wrong, and the engine could begin cranking without notice! Keep it in neutral and hands clear!
 
Do it the poor mans way. Take cable off starter then put battery cable on to see if it sparks. You can eliminate one thing at a time. May have a bare wire touching metal.
 
Thanks for your suggestions. I still get a BIG spark after one by one, disconnecting the starter, the generator, the voltage regulator. I recleaned and shined up the battery ground contacts. Still spark at + terminal when I try to connect battery cable. One thought is the starter switch. How would I test that? There are 3 wires going to power side of switch--the negative battery cable, the ignition wire and something else. There is one wire going from the other side of the switch to the starter.

Could the starter switch be broken or fused inside?

Getting closer, I hope.
 
It is possible the contacts are fused, but with the starter cable disconnected, that should stop the spark. Try that first, disconnect the starter cable from the starter. Reconnect the battery, see if the spark stops. If the starter cable has power with the starter switch NOT activated, the contacts are fused.

The other wires connected to the battery side of the switch are the accessory feeds for the rest of the electrical system. Try disconnecting them, then reconnect the battery. That should stop the spark. Then try touching each wire to the switch post, see which one sparks. Then follow that wire, see what it feeds. I believe one goes to the amp meter, from there to the ignition switch. The other should go to the cut out relay or regulator. It's just a process of elimination, disconnecting each wire, testing for spark. Just be sure to reconnect the wire after each test so you don't get them mixed up.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top