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Why is my battery cable getting so hot?

SwedishBee

Drill em deep
Joined
Jun 21, 2009
Location
TX
Why would my positive battery cable and clamps get so hot you cant even touch them, the rubber insulation is getting so hot its on the verge of melting.

The car seemed fine, I only noticed it because I needed to borrow the battery for a different volvo and that car ran it fine.
Is it possible the alternator went bad and is overcharging? Or do I have a short somewhere...
Maybe the starter?

This is a shame because I have sold this car and was getting close to delivering it.

This is the 95 960
 
Im short on batterys so whenever I need to move cars around I have to play musical batterys.

I borrowed the battery that was in this 960 for my 242...
While pulling the 960 battery after a 5 minute drive, is when I noticed the problem.

Hopefully that makes sense... Im tired
 
Most of the wires are gone, which gives the cable a smaller wire size and higher resistance. It now can't handle as much current.
Try measuring voltage drop across the cable. Higher voltage drops will make the cable get hot.
 
well here is the rest of the story, when I first got the car together a few months ago, The car drained the battery in the first day or 2, and it turned out being a loose alternator cable nut.
The alternator cable got hot then and melted some insulation near the alternator. I tightened it up and have driven 1500 miles since.. I dont think the alternator wire was hot this time, just the main battery cable...

Should I replace the alternator to starter cable and get a new positive battery cable?
 
Most of the wires are gone, which gives the cable a smaller wire size and higher resistance. It now can't handle as much current.
Try measuring voltage drop across the cable. Higher voltage drops will make the cable get hot.

Another thought, if the positive cable clamp is not tight on the battery, would it get hot like this?
 
Resistance of the battery cable is to high for the current draw being applied to it. You may need a new cable, you may also have a short somewhere. Does the terminal make a noticeable spark when you connect the battery?

Another thought, if the positive cable clamp is not tight on the battery, would it get hot like this?

No, that would not cause the cable to get hot.

Yes that could create more resistance as well since it's not clamped down tightly.

Read above.

Battery cables are cheap, but a new one.

Yes.
 
Another thought, if the positive cable clamp is not tight on the battery, would it get hot like this?
Mainly at the terminal. If the starter pulls enough juice, you can melt the lead.
Also if the starter is going bad... I though one of the batts on my diesel was going out awhile back, stopped at the parts store, and had em load tested. Both were fine, but my starter was pulling 400 Amps to get maybe 6 RPM, and it got hot enough to weld the lockwasher on the starter terminal back into a flat one.
 
Damn. It has always turned over slowly. The last time I drove it I drove 200 miles in a day,
Maybe I will change out the alt>starter cable and the starter>battery cable and also the starter itself.
Thoughts?

duh
I just remembered that I pulled this engine from a smashed car at the junkyard, they couldnt even get the battery out of it. I came along and cut it out... maybe the starter got burned up from shorting out in the wreck.
 
Damn. It has always turned over slowly. The last time I drove it I drove 200 miles in a day,
Maybe I will change out the alt>starter cable and the starter>battery cable and also the starter itself.
Thoughts?

duh
I just remembered that I pulled this engine from a smashed car at the junkyard, they couldnt even get the battery out of it. I came along and cut it out... maybe the starter got burned up from shorting out in the wreck.

Or, you could save yourself the hassle/money and just replace the cables.
 
I already have another starter. If there is any chance of it being the problem I think I should just swap it...
 
You are making this very complicated and it is not.

Are both cables getting hot?

Yes, then both cables may have to much resistance for the current going through them or both cables-connections may be bad. Connect an amp meter up to either one to verify the loop current and go from there. A current of over 15-25 amps with the lights off and blower off is too high. If the battery is shorted and drawing too much current then the alternator is over working and it should be quite warm too. What is the voltage at the battery with the engine at idle?

If one cable is only getting hot then you need to clean the connection on both ends and/or replace the cable.

Any excessive resistance of a cable will dissipate heat. Once copper gets too hot it will always have an increased resistance.

No, the starter should not cause the heat in the cable.
 
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