Jumping a Car Battery

You might think I'd be a pro at this, but I'm really not, so maybe someone can help explain something to me.

My wife left the dome light on in her car Wednesday night, and then didn't use it at all on Thursday, so the battery was dead when she went to use her car this morning.

Of course, her car was facing the wall of the parking garage we park in, so after rolling her car out, and moving it up against mine, in a place where we wouldn't be blocking the entire garage, I went about jumping it.

I attached the cables this way: Positive to positive, negative (good car) to ground (dead car).

The first attempt, didn't work. I did it again, making sure all the connections were good (my positive connection is basically buried under a hose, so it's a pain in the ass). It still didn't work.

Tried again with a different set of jumper cables. Nothing.

Finally, I moved the black cable on her car from ground, to the negative terminal on her battery. Worked like a charm. Car fired right up.

Couple of questions. Why didn't it work the way I tried? Was the ground not a true ground? Why are you instructed to do it that way anyway? Why not just attach it to the negative terminal on the dead battery? Is it a safety thing?

 

You should have had one of the cables connected to your balls?

On a serious note, I never ground the negative cable. I always try to go battery-to-battery when possible.

 

I was always taught you had to (1) positives to positive; (2) negative of good car, then (3) ground the dead car.

Whatever you do, never, ever, get the lines crossed, positive to neg. Major meltdown.

 

Had to jump my car last night. It's weird my battery has a + sign with a red cable. It's always confused me, but now I know to disregard the plus sign and just go red-red, black-black.

 

Traditionally, the red will be the positive, and the black the negative.

 

Which is stupid as hell for anyone wired to think about money or finance. Always thought it was a conspiracy to sell more Diehards.

 

I have never in my life grounded the negative.

Just red to red and black to black and then fire it up.

 

See, that's how I remember it as a kid, but any instructions you read will tell you to ground the black to the frame of the car with the dead battery.

I don't know why. I assume it's some kind of safety thing.

 

Attaching the negative cable to ground on the dead car prevents a spark from igniting hydrogen gas that can accumulate off the battery. As to why it didn't work, likely not a true ground. Did you attach it to the engine block or the frame?

 

Weird. News to me.

Then again, I am certain my grandfather taught me how to jump a car forever and ever ago. Never had any problem, though.

 

I always did the red/red, black/black thing too. I am under the impression that connecting it this way opens slight possibility of damaging the good battery, but I have never had a problem. The ground thing is the common method now, but I've never done it that way.