What causes a battery cable to melt?

[panthermike]

I was driving the '77 F250 last night when it started making a "whirring" noise. Then after I turned a corner it just shut off.

Come to find out the cable going from the solenoid to the battery; melted at the terminal!

I'm trying to figure out what could cause that, and if I should do something else other than replace that cable?

 

[OVERKILL]

A bad connection or a short.

 

[mechjames]

Whirring could have been your starter.

Check all connections to the solenoid. Might be best to replace the solenoid too, if whatever shorted out drew power that long through the cable, it means it was drawing power through the solenoid too.

 

[bullwinkle]

Solenoid welded itself shut-the cable melted before the starter or battery died. Lucky there wasn't a fire!! The "whirring" sound was your starter engaged while the engine was running-you may need one of those too.

 

[Donald]

Hmmm....NOTE TO SELF..add a large wire cutter to the vehicle tool box,

 

[bullwinkle]

I've wondered myself what would happen on my old F-SuperDuty diesel if that happened-2 newer 1000 CCA batteries contain a LOT of electrical energy!

 

[The_Eric]

Speaking from experience, use a OEM solenoid. Some of the aftermarket ones (our bad experience came from Borg Warner) don't have heavy enough contacts and will arc shut, keeping the starter engaged. We've had two separate instances where this happened- twice one on truck!

Make sure that the cables are in good shape as well. Anything that will cause a voltage drop (and resulting increase of current draw) will increase the likely hood that your contacts will weld shut.

 

[panthermike]

Thanks for the feedback, sounds like next weekend I'll be doing the cables and the solenoid.

I think I'm lucky there wasn't a fire or anything, I was worried at first because there was smoke.

 

[doitmyself]

IMPORTANT!

There's chance that the wire that melted was a fusible link wire. They sometimes look no different than a regular wire. They are designed to melt before something gets damaged. If it is a fusible link wire, replacing it with a regular wire could cause more damage or even a fire.

Google Ford truck fusible link wire for lots of info. They come in different ratings/gauges. You can buy the wire or get this below with terminal and crimp (Advanced Auto http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Fusible-Link-Wire-Carded-Ford-18-Gauge-Dorman---Conduct-Tite_22141118-P_N3062A_A|GRP2020A___)

You need to determine the problem. In my case, wire insulation rubbed through to cause a short.

 

[RH+G]

If it looked like it just melted at the terminal it probably became loose.
If the whole wire looks burnt and crispy all the way to the solenoid then the solenoid was stuck and drawing excessive current

 

[panthermike]

doitmyself, the wire that melted didn't look like that. It was a standard/thicker wire from the solenoid to the battery terminal.

 

[panthermike]

Oops, forgot to update this thread.

Last weekend I changed the battery cables, solenoid to starter cable, and the solenoid (Motorcraft). The truck still wouldn't start. Ended up that the starter was done, which I figured it would be.

The starter was under warranty, so I got her running for $53. I've driven it maybe 30 minutes or so since the fix, so far so good.

 

[morris]

thats the way you learn. good going.