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Electrical system failure after a jumpstart?

So a co-worker needed a jump after leaving her lights on and I thought I would be a good samaritan and help her after work. Her car was parked on a busy road and I had to pull up next to her in the opposing traffic lane to be able to reach her battery. In my haste I put the clamps on the wrong battery terminals on MY car (hers were correctly attached). When I got in my car to start it I could see the wires were smoking and immediately got out and disconnected the cables. We ultimately needed to purchase new cables and were able to start the car. The problem is now her radio doesn’t work and when she brought it to the dealer they said there is some kind of electrical system failure?!?! Is that possible? Her car works perfectly fine, except for the radio now so not sure what happened. Please help as I may be responsible for money for repairs!

Be thankful if only the radio failed. You could have had a battery explode in your face.

You are very lucky it’s just the radio…Reversed cables are reversed cables…It makes no difference on which battery the cables were attached incorrectly…

That mistake could come back to haunt you and your friend.

Damage to the radio is not only possible, but likely. As others have said, if that’s all that was damaged, you’re lucky.

You didn’t ask this, but I think you should be paying for her radio repair.

Live and learn. You won’t likely make that mistake again…
… hooking it up backwards, that is. Helping someone that needs it is never a mistake so don’t stop doing that.

FWIW, you can probably get her a really nice replacement radio from Crutchfield for not crazy money and get it installed for way less than a dealer would charge.

First, check the fuse. It probably just blew. This happened to me one dark and stormy night when a friend was helping me jump my car. I didnt’ realize he put red to negative and black to positive, and so inadvertently reversed the wires. I learned that night to always go solo when jumpstarting a car :wink:

Anyway, it blew my radio fuse, the headlight fuse and (sigh) the 100 amp main fuse, which was fun to find at 9pm when most parts stores were closed.

That is a good suggestion and I hope you’re right but doubt it because it fried his cables first, before any fuses blew…

depends on how cheap the cables were. Cheap ones will get really hot even when they’re hooked up correctly.

What kind of cars are we talking about? I once serviced a VW Jetta that had the same type of accident–reversed jumper cables. I was able to correct all of the issues on the Jetta save for radio operation. Closer inspection showed a blown fuse IN THE BACK OF THE RADIO, that required radio removal to access. Who designed that system I don’t know but I’d sure like a word with him.

The cheap cables may have limited the amperage flowing and prevented extensive damage to the car…The cables themselves sustained most of the damage…

We’ll see. I hope for the poor Samaritan’s case it is just a fuse.

red goes with the
’+" bkack goes with the “-”: ok on both cars

If the trouble is due to just a simple problem with the power I would think the shop should be able to figure that out without much trouble. Some of the newer style radio designs reqiure a code be entered into the radio if the power to it has been disconnected, or reversed in this case. I would think the shop would be aware of that also.

By attaching the cables backward, you’ve essentially done two things:

  1. you’ve created a closed loop between the two batteries, with no external resistance in the circuit. You could absolutely cause the battery to explode in this matter from the sudden heat generated by the chemical action of the batteries caused by the current suddenly running around freely in a circle. And by putting the batteries in series you’ve doubled the current flow that can ensue.

  2. some of that high current flow can go through the car’s circuits, blowing fuses and even blowing out the dielectric in diodes and the boundry areas in transisters.

You lucked out. If she asked for the assistance, knowing you’re not a professional, she should accept the responsibility for the cost of repair. If you offered the assistance, knowing you’re not a professional, IMHO you should accept responsibility for the cost of the repair.

By the way, Caddyman may be right. If they were cheap cables they may have had enough resistance to prevent even more damage.