Jumped friends car .. burned headlight!

mrDFWmechanic · #1 (**permalink**) 10-10-2009, 08:19 AM

So my friend called me asking to come over and jump his car at a restaurant 3 mins from my house. I get there his BB wasn't cranking so he hands me the cables I hookup my side he does his. I start the fit and he tries but the BB just clicks so I gave it some gas to help out. After 1 min I get out to look and the insulation on the jumper cables are bubbling and melting. I pulled them off and noticed they burned a couple nice marks into my pass. headlight. My friend hooked the negative onto a bolt on the strut tower so thats what caused the wires to melt. He played it off like it was the jumper cable malfunction so now I have to wetsand my headlight to get the burn marks out. It could be worse his grill and bumper got burned and yellow marks on them so serves him right for being a know it all.

Flyin172s · #2 (**permalink**) 10-10-2009, 09:56 AM

I thought that's how they should be hooked up. You hook up the pos/neg cables to your battery and he hooks up the pos cable to his battery and neg to an unpainted metal surface. It bonds the cars together, reducing chance of a spark and then a boom.

mugen boi · #3 (**permalink**) 10-10-2009, 10:28 AM

thought it was supposed to be 'positive to positive' batt terminal n 'negative to negative' batt terminal

mrDFWmechanic · #4 (**permalink**) 10-10-2009, 11:09 AM

I've always hooked up battery to battery even instructions on the jumper cables say to do so. Now I have to find some sandpaper and wet sand my friends stupidity off my headlight.

JJorda · #5 (**permalink**) 10-10-2009, 10:53 PM

I've always done it positive to positive and negative to negative, but the "correct" way should be a good ground on the car to be charged instead of the negative terminal. From what I remember of what I read, doing it this way will lower the peak current through the cables and provide a little extra resistance in case of a dead short to ground.

If your cables were getting hot, they were too small of wire gauge for the current passed through. Do they have a size stamped in the insulation? Should be a number followed by "AWG".

kenchan · #6 (**permalink**) 10-11-2009, 12:01 AM

sounds like your friend's car has a short somewhere. his car should've started without you giving more gas for your car.

and yah, black to black, red to red on your batteries when you jump.

Gigarange · #7 (**permalink**) 10-11-2009, 03:16 AM

hooking the negative cable to the strut tower bolt vs the negative post of the battery should make no difference.

There are several cars out there that use a "bolt" on the strut tower as the only way to provide a jump start and it is labelled as the "NEG" connection.

My guess is there is something else going on that caused this, if they were legit jumper cables, it's more likely that them being hooked up imporperly causeing the melting problem rather then attatching it to a bolt on the strut tower causeing it.

As Kenchan mentioned, if everything was hooked up properly and it was just a dead battery, you shouldn't have had to "giving your car more gas to help"
I've used my car to give a boost to my work truck which was a large diesel truck with 3 batteries of it's own, without giveing my car "more gas"

willmax11 · #8 (**permalink**) 10-11-2009, 10:20 AM

There are diff. gauges of wire used for booster cables. Maybe he
used too light a gauge cable or the draw was too high for too long.

Secondly, if my battery is in good shape, I never have my engine running.
If someone hooks it wrong it could blow the circuit in my car. Only the
batt. is in danger with the key off. (Think off a battery carried to a car needing a boost.)

Booster Cables | Canadian Tire

brdss · #9 (**permalink**) 10-12-2009, 09:38 PM

Hooking the negative to the strut did not cause the cable to melt. They were too thin (probably really cheap cables) and the high flow of current melted the cheap cables. The negative terminal of the battery is connected to the body of the car. If you want to check it, place an ohm meter between the neg terminal and the strut tower. it will read less than 2-3 ohms.

Now if you said that he hooked up the POSITIVE cable to the strut tower, thus going directly to ground, then yes, it would be his fault.

doctordoom · #10 (**permalink**) 10-13-2009, 12:25 AM

yea people who are saying your friend properly connected the negative end are correct. putting it on the strut bolt is safer than putting it directly on the negative terminal of the dead battery (i would have picked something on the engine block but that's just my preference). any exposed metal on the dead vehicle is fine, since it is all connected to the negative terminal of the battery anyway. it's safer that way because when you complete the circuit you can get a spark, and it's safer to have the spark away from the battery.

Gffy2334 · #11 (**permalink**) 10-14-2009, 08:37 AM

BTW the reason that a spark is dangerous is because overdrawn batteries, become hot, and the electrolyte inside them starts to bubble and gas out. The gas coming off a venting battery could ignite if a spark is strong enough and close enough to the gas source.