# Is this a dying battery? (Car question) **URL:** \ **Category:** Factual Questions\ **Created:** [September 18, 2012, 11:40am UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062 "2012-09-18T11:40:43Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [September 18, 2012, 6:20pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/21 "2012-09-18T18:20:40Z")
> [@Rick](#): > > Ummm no. > You can connect the negative first and maybe not have a bad result ( as long as the wrench you have on the positive cable doesn’t touch ground you are golden) > The REALLY important thing is to make you connect positive to positive and negative to negative. Put the cables on the battery backwards and it gets very expensive very quickly. Electronic control units don’t like being hooked up backwards. > And yes I have seen customers do this. I have also seen $2500 repair bills as the result. I think you’re talking about jumping (+to+/-to-) and filmore is talking about disconnecting the battery to bring in if no one is available for a jump. I actually just had the same exact thing happen over the weekend, Frylock. Went to start the car and just got clicking. Was able to jump it and let it run for a bit. Then tried to start it again Monday after work and it was dead again. Jumped it again and drove down to the nearest car parts store and bought a new battery and switched them out (and yes, disconnect neg first). Car is close to 5 years old so I figured it was time for a new battery anyway, but the car parts place said they’d help me diagnose it if I have trouble even with the new battery. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [September 18, 2012, 6:58pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/22 "2012-09-18T18:58:14Z")
> [@SmellMyWort](#): > > I think you’re talking about jumping (+to+/-to-) and filmore is talking about disconnecting the battery to bring in if no one is available for a jump. with the NEG cable connected all the metal of the auto body is a NEG wire. if you have a wrench that while disconnecting the POS cable, touches the auto body then you have a short circuit (along with sparks for a charged battery, potential damage to the battery). if you disconnect the NEG cable first then this danger is eliminated. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 18, 2012, 7:29pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/23 "2012-09-18T19:29:09Z")
> [@SmellMyWort](#): > > I think you’re talking about jumping (+to+/-to-) and filmore is talking about disconnecting the battery to bring in if no one is available for a jump. No I was talking about replacement of the battery. I have seen cases where some slightly less than brilliant induhviduals connected the positive cable to the negative terminal and the neg cable to the positive terminal of the battery. The results are impressive and can be very expensive. Same thing will happen BTW if you screw up a jump start. ---
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [September 18, 2012, 7:44pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/24 "2012-09-18T19:44:10Z")
> [@Rick](#): > > No I was talking about replacement of the battery. I have seen cases where some slightly less than brilliant induhviduals connected the positive cable to the negative terminal and the neg cable to the positive terminal of the battery. > The results are impressive and can be very expensive. > Same thing will happen BTW if you screw up a jump start. OK. I thought your “ummm no” was disagreement with filmore about the order of the cables, but it looks like what you meant was that the “really important thing” isn’t the order, it’s making sure you keep the +s and -s straight. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [September 19, 2012, 2:28pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/25 "2012-09-19T14:28:31Z")
What’s the deal with connecting the good car’s negative to the bad car’s unpainted metal instead of the bad car’s negative? Is this actually necessary, or is it kind of a car repair old wive’s tale? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [September 19, 2012, 2:40pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/26 "2012-09-19T14:40:04Z")
> [@Frylock](#): > > What’s the deal with connecting the good car’s negative to the bad car’s unpainted metal instead of the bad car’s negative? Is this actually necessary, or is it kind of a car repair old wive’s tale? a spark would happen when you connect the final jumper cable. if the battery contained explosive hydrogen gas (which it can) there is a chance that it could explode. connecting the electrical circuit at a point away from the battery is intended to prevent that hazard. ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [September 19, 2012, 3:26pm UTC](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062/27 "2012-09-19T15:26:00Z")
> [@Frylock](#): > > What’s the deal with connecting the good car’s negative to the bad car’s unpainted metal instead of the bad car’s negative? Is this actually necessary, or is it kind of a car repair old wive’s tale? The safest way to jump start a car is to connect positive on good battery first, then positive to bad battery, negative to good battery, then negative to ground (unpainted metal inside the engine compartment will do…brackets, bolts, etc). Also, if your battery is really depleted sometimes it cannot be jumped. I keep cables in my car and have jumped many customers at my car washes as they often leave the radio blasting for llong periods of time with the engine off, then wonder why it won’t start…and I had a lady the other day that I just couldn’t get her car jumped, so I disconnected the battery for her, drove her and the core to an Autozone, got a new battery, installed it and bam, started right up. [Previous page](https://boards.straightdope.com/t/is-this-a-dying-battery-car-question/635062.md?page=1)