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Melted battery terminals

19K views 18 replies 8 participants last post by  Twistid 
#1 ·
Ok somebody asked me to start a new thread on this, so I will start at the beginning. I have been having some electrical issues with starting (at least I am assuming it is electrical). Since the end of last summer when I try to start the bike I was getting either no response from the ignition, solenoid chatter or slow cranking with the battery draining it's charge. So I assumed it was the battery and bought a new one, it worked fine the first few starts. This past weekend when I went to start it cranked slow again then died. I removed the battery cover to find that both of the terminals had melted. So I spent Saturday afternoon going over many of the wires looking for loose connections (as advised in the last thread) but I didn't find any, I tried to test the starter while it was still on the bike but that didn't work. I am going to take the starter out and have it tested. Any other thoughts to what could be going on???
 
#2 ·
Anytime there is resistance. Electrical amperage will cause heat. Loss of amperage to what your powering up. If the cable ends were both melted. I'd think they were not tight in the 1st place. Or poor-bad connection where the cables wire goes into the end. Internal.

Have an ohm meter? Stick a needle into the insulation just after the burnt part. Use the ohm meter to probe the cable end and needle. 0.0 is a good connection.

If your cables were not making a good connection. 2 things happen. One is hard to start, other is lack of charging up the battery when running.

If the cables test out bad. I'd replace them before I pulled the starter out.

Use the ohm meter at the volt settings. Test battery volts when your trying to crank it over. Before you try to start and during. You should see around 12.7 to 13v before.

On starting, it should drop somewhere around 9-10v. If you try to start it and the battery volts didn't drop much and cranks over slow. Electrical wiring issue.

Voltage drops like a stone. Bad battery or starter issue. JMHO.
 
#3 ·
well said

This is a good place to start.
 
#4 ·
I took the starter out last night and tested it. It was locked up. So I ordered a new starter. While I am waiting for delivery I will take apart the broken one and see if I can't find the short in there. All the cables look good and test fine, the battery however, not so good. I am going to check a few more things before putting it all back together. I would hate to put on the new starter just to have it burn up again. I don't know how that could happen, but stranger things have happened.
 
#5 ·
Look in your yellow pages for a local electric motor shop. He can test your current starter windings for a short.

It appears to me it's dead short somewhere. A bad connection would drop some voltage across it and make your starter not turn as fast or not turn at all, but I can't see it melting your terminals, unless you held the starter on at near locked rotor state for a long time.

To do that it's got to be a dead short allowing hardly any resistance at all and current flowing wild resulting in the heat. Amps = Volts divided by resistance, so if you got high amps (heat) you've got verly little resistance.

And further you don't say that your blowing any fuses, so unless your main fuse or breaker is bad, that would seem to narrow it down to the unfused Positive wire going to the starter area. Check that wire along it's full length for bad insulation that is touching to bare metal ground somewhere.
 
#6 · (Edited)
On the blown fuse. At least on my Fat-Boy and thinking all Harleys would be wired the same. No fuses would blow.

Turn the key on, gives power to the starter switch, once closed. Gives power to the starter relays electro-magnet. Makes the internal contacs close to give power to the starters solinoid. Solinoids electro-magnet closes and makes 2 internal contacs touch.

I:E Low amperage power controlling hi amp draw @ the solinoids internal contacs. Energized or not.

Those 2 contacs. One is from the batterys pos cable to one contac, other contac goes to the starter itself.

When the starters solinoid made the contacs touch. Hi amp draw from a bad starter would create heat at the battterys cables. Melting them.
 
#7 ·
That's where I am at with it Loco. No blown fuses, and there isn't a fuse between the starter and the battery. My thinking is the starter was bad, maybe a short in the starter and when I went to start it, it tried to pull more amps then the battery could give, discharging the battery rather quickly causing the terminals to melt. While I am awaiting my new starter I plan on taking the starter apart and checking to see if I can find the short. Even though I have been over the wiring a few times now, I am not completely convinced that's the problem. I can find no indication of a short elsewhere, but I most certainly don't want to put my new starter and battery in only to fry them again when I try to start the bike.
 
#8 ·
The only other thing I could think of. If the starter itself checks out ok. The starter solinoid internal contacs might be burnt. You say you tested it and it was locked up.

If the solinoids contacs were burnt, you wouldn't get enough power thru the solinoid to turn over the starter.

Energize the solinoid with a battery charger. Where the small green wire attaches. ( At least on my bike it's green. ) Test across the batterys input lug and output side with an ohm meter.
 
#9 ·
Over the weekend I took apart the starter/solenoid. Here is what I found: The field wire connection on the solenoid side was extremely corroded and there appears to have been an arc from the positive battery cable stud to the plunger? There is a small amount of scoring and carbon built up on the copper plate that the positive cable connects too, but the plunger looked fine. I don't have much experience here but it just didn't look right to me. When I took apart the starter side I noticed a large amount of rust built up on the flange between the yolk assembly and end frame. I am not sure how that would happen since the starter is painted after assembly and I couldn't separate the two pieces with out breaking the seal the paint had made. Once inside the starter, it didn't look as neat as I thought it would, there was a dusty black/red build up through out. To me it just looked like a lot of corrosion has gotten the better of my starter/solenoid. Not sure exactly how but I am going with it. I still can not find any short in any of the wiring, but I think I should buy a new positive battery cable as well. Since I am still waiting for the starter to come in I will check the wiring again, maybe I am missing something, and the way things have been going lately I probably am.
 
#11 ·
Lightly sand the copper where you see the arcing area. The arcing it fine. Everything else looks good but you should test it all. The tests are found in the Factory Service Manual and are pretty easy to follow.

The large copper washer usually has one side that is all covered with arcs. Just flip it over and put it back in. If the "clean" side has any tarnishing to it, use a fine sand paper and clean it off.
 
#12 ·
The battery terminal is corroded a little, just clean it up good and reassemble.

A simple bench test before you put it back in the bike to see that it all works. Reassemble the solenoid. Hook it up to a battery with jumper cables. Use a piece of wire and connect one end to the Positive battery terminal. Then touch the other end to the solenoid terminal. Be careful as the starter has a lot of torque and will jump. Keep your hands away from the starter gear.

If everything work, the starter will engage and spin. It should spin freely and fast. If it sounds like it is working hard to turn, it may have other issues. It is also difficult to tell the two apart if you don't have one to compare it too.
 
#13 ·
Glad to hear you found the culprit. Sounds like you have a bit of what a friend of mine calls carbon tracking. It can also cause a starter to keep turning sometimes even after you let go of the button. A small amount of moisture can mix with the carbon build up and it will conduct current.

Sounds like after you get everything all cleaned up you will be good to go. Although I'd make sure none of that rusty moisture is getting in near the contact area.
 
#14 ·
Problem solved and root cause determined..... I think. I received all of my new parts and put them on (starter, battery and positive battery cable). After I put everything back together I decided to take apart the positive battery cable. I removed the insulation and found that the cable was wet (behind the insulation) and corroded. How it got wet, I don't know, but the moisture had begun to corrode the cable inside the insulation. I can only guess that the combination of water and corrosion of the cable and corrosion of the field wire and bolts were responsible for the destruction of my battery and starter. Guess I will pull over next time it rains. Probably NOT. Anyway the cable must have got wet sometime last year seeing how I haven't been able to really ride yet this year and she spent the winter covered in the garage. I do find it odd though that all of the corrosion occurred behind rubber covers and insulation, both ends of the battery cable were clean and free of corrosion, along with all of the grounding wires and somewhat exposed connections. The corrosion only occurred in areas protected by boots or insulation. Oh well, I am happy to back on the road, and with a shinny new chrome starter. Thanks for all the help guys.
 
#16 ·
Good to see you opened up the insulation to find the problem. You went the distance to find what was really wrong. The wetness traveled up into the connector and if you took a dremmel to cut it open. You would see how the inside looked.

If you think it would happen again. Use some silicone around the rubber cover ends.
 
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