Heading Out on Your Own — Day 28: How to Jump Start a Car

by Brett & Kate McKay on August 28, 2012 · 34 Comments

in Heading Out On Your Own, Visual Guides

1. Pull jumper car next to car with dead battery. Make sure both cars are turned off and pop their hoods.  2. Connect one end of the red (positive) jumper cable to the positive terminal on the stalled battery.  3. Connect the other red (positive) cable clamp to the positive terminal of the good battery.  4. Connect one end of the black (negative) jumper cable to the negative terminal of the good battery.  5. Connect the other black (negative) cable to a clean, unpainted metal surface under the disabled car’s hood. Somewhere on the engine block is a good place. Do not connect the negative cable to the negative terminal of the dead battery.  6. Now start the car that’s doing the jumping and allow it to run for 2-3 minutes before starting the dead car. Remove cables in reverse order of how you connected them. Keep the jumped car running for at least 30 minutes to give the battery sufficient time to recharge itself.

For a text article on the subject, see here.

{ 34 comments… read them below or add one }

1 waykno August 28, 2012 at 10:59 pm

You mean it doesn’t matter if it’s positive or negative ground? It would have to be an oldie for a negative ground but….

2 Toby August 28, 2012 at 11:15 pm

Hang on… You should be hooking the ground (black) cable first, then the live (red) cable last.

It should go: Black end to the stalled car, then black end to the live car battery, red end to the dead battery then red end to the live car battery.

You ground first and hook up the live battery last. Then remove in reverse.

3 Rob August 28, 2012 at 11:16 pm

Why is it ‘do not connect the negative cable to the negative terminal of the dead battery’? I have done so and never noticed a problem – I have heard it’s better to attach to the frame, but please explain why not to the terminal?

4 Anthony August 28, 2012 at 11:25 pm

Growing up I’ve seen many a car get jump started and picked up the tricks by the age of six. What surprises me is in high school I had friends who were 17/18 that still had no idea how to jump start a car. Most of them also were unaware that you could take a good battery from one car then swap it into the dead car Then start the dead car, switch the batteries back and drive a short distance, say enough to get home, as long as you used no electrical parts such as the radio or lights. Of course this is basic info most people know but you’d be surprised how many truly have no clue. Another great page in every man’s handbook from AOM.

5 Brett McKay August 28, 2012 at 11:29 pm

@Toby-

Not so, at least according to these…

http://autorepair.about.com/od/roadsiderepairs/ss/How-To-Jump-Start-Your-Car-Using-Jumper-Cables_2.htm
http://www.edmunds.com/how-to/jump-start.html
http://www.cartalk.com/sites/default/files/features/jumpstart/images/jumpstart2012.pdf

…and any other trusted source you can find. You can definitely trust Click and Clack!

@Rob-
Apparently, with some batteries, at least in the old days, there was a possibility that it could cause a spark that could ignite hydrogen gas. Better to be safe than sorry.

6 caleb August 28, 2012 at 11:31 pm

If gasses collect on top of the battery it could explode. I usually do both on the dead and then the live one.

7 Peter August 28, 2012 at 11:32 pm

It should indeed be ground last, and make the last connection to the (earthed) body, not the battery terminal.

The last connection is completing the circuit, and it’s very easy to generate a spark while doing so. You connect to the body to keep that spark away from the battery, reducing the risk of starting a fire.

8 Peter R August 29, 2012 at 12:48 am

Now how about a guide to clutch starting a car? Its a skill that many are unaware of with a world full of mostly automatic transmission cars.

9 Nathan August 29, 2012 at 12:56 am

Don’t drive like my brother!

10 Demian August 29, 2012 at 4:44 am

Just on a side mote: For the jumped (?) car its a good idea to i) activate every consumer, before jumping it (lights, radio, heating) and, even more important ii) when recharging the battery by driving/with the engine you should absolutely leave the lights on, since some cars do not activate the alternator, when the lights are not on and thus want recharge the battery!

11 Paul August 29, 2012 at 7:00 am

@Rob-
My driving instructor in high school told my class that this prevents the flow of electricity from entering the wrong terminal (as in possibly getting the cables mixed up). The electricity flows out of the negative terminal of the good battery into the positive terminal of the dead battery. If the power flows into the negative terminal, the battery could explode, which was what happened to my driving instructor. And since the negative terminal of the dead battery is disconnected, there’s no chance of anything flowing out of it and back into the good battery, so the good battery won’t blow up.

12 Calvin August 29, 2012 at 7:54 am

In the first step always make sure that the vehicles are NOT touching each other. This was a bigger deal back when chrome bumpers were more common but it’s still something to watch. You’ll get a second ground circuit if they are.

13 Matt August 29, 2012 at 8:26 am

My father always taught me to duck down when connecting the last terminal, since the batteries sometimes produce hydrogen gas when charged. If there’s a spark when you connect the last terminal you can end up with a big fireball right in your face. Ducking will get you out of the way of the worst of it.

14 Martin August 29, 2012 at 8:34 am

Thank you. I have done it this way for a few years now. This is a compact graphic that I can print and give to my kids to keep in their car.

15 JD August 29, 2012 at 8:34 am

I’ve heard that it’s also important to not only keep the car running but to actually drive it for at least 20 minutes if not 30. Idling won’t do too much to re-charge the battery but driving will.

16 Toby August 29, 2012 at 9:37 am

Thanks Brett and Peter!

I was taught to ground first, which seems to make sense to me because you want a ground wire when you hook up the live terminal. But apparently this is not correct, so thank you for the correct info!

17 JCMasterpiece August 29, 2012 at 9:43 am

That’s funny, because the instructions on my jumper cable case (what I have been using successfully for well over a decade) say to connect the black cable to both batteries and change the order depending on how it is grounded.

18 Moeregaard August 29, 2012 at 9:48 am

All lead-acid automotive batteries produce hydrogen gas. The idea behind making the final connection away from the battery is that any spark from that connection will be far enough from the battery to prevent ignition of that gas. It’s also worth noting that eye protection is mandatory whenever you’re messing with any car battery.

19 Zeke August 29, 2012 at 9:52 am

Yes, keep the spark of the final connection away from the battery, in case the battery has a crack or is leaking vapor that can ignite. But having that spark on the frame or block is useful for checking the quality of the connection, ie, you see a spark, you’ve got good connection.

But I have always kept the “jumping” car running…if the “good” battery is weak, or old, and the bad battery is drained enough, or it is cold enough, your rescue attempt can leave you with TWO cars with dead batteries, which does nobody any good.

I’m sure this isn’t what is considered safest practice, but I think it is still the best plan, to avoid double your trouble.

20 Rich August 29, 2012 at 10:24 am

Hey Brett,

Found the AoM a few months ago and it’s been part of my lunchtime routine ever since!

It’s been over a decade now, but my high school automotive/vocational teacher preached “red on dead” for the first step; I can’t remember what I had for dinner yesterday but put something in a rhyme and I’ll never forget it.

Thanks again, and keep up the good work!

21 Josh August 29, 2012 at 11:33 am

To clear up a little confusion here, there is no “ground” connection on a car battery. There is only a positive and negative, neither of which are remotely equivalent to a ground connection. Ground connections require something that the car is 100% insulated from via its rubber tires: the ground.

The reason you do one on one car, then do the other car before connecting the last one on the first car is because it makes it difficult to short the connection. If you hook both contacts up to a single battery first, the other clamps may very easily touch each other and cause a short.

The reason you do not make the final connection directly to the battery itself is because batteries can emit flammable gasses which can be ignited by the spark that occurs when you complete the circuit. Older worn batteries (i.e. more likely to be dead batteries) are even worse at this. Although making that final connection directly to the battery contact will get the power through and get the car started, it’s an important safety precaution to never do so.

The reason you connect the positive first is because a negative charge is actually the one that has the electrons, not a positive one (weird, I know, but that’s how it is). You want to establish the entire pathway for the electrons to travel before you unleash the horde.

22 Aaron August 29, 2012 at 12:06 pm

I’ve printed this out and put it in my car with my jumper cables!

I always forget which order it goes in. Thanks again.

23 Tim August 29, 2012 at 12:29 pm

I’ve had two instances where I couldn’t start the dead car using the above technique, so I moved the final black clamp directly to the dead negative terminal (instead of the frame), and the car started.

I guess it could be either not finding a clean metal surface, or less resistance because of a direct connection to the battery.

I also understood while doing it that I was taking a risk — I just tried to be deliberate about it so as to reduce the amount of sparking.

24 Chris August 29, 2012 at 11:49 pm

if you live in a cold area get a good quality cable with a big cross-section. (25mm²+)

cheap jump cables are mostly way too slim, its ok for small gasoline engines in hot weather. But on a freezed car or an Diesel engine they mostly wont work.

25 Jason August 30, 2012 at 10:58 am

Nice little graphic!

So do you leave the cables connected when you start the stalled car too?

Just leave everything connected until both cars are running and then disconnect?

26 Terry August 30, 2012 at 12:51 pm

Great article and excellent discussion!

Something that has improved my ability to utilize my jumper cable over the years, is that I bought mine with extra long (16 ft.) cables.

Depending on the location of the batteries, a short cable length can be a deal breaker when it comes to giving a car a jump.

27 waykno August 30, 2012 at 6:00 pm

Now that many of you are confused, let me add another caveat—take off any jewelry while working around a battery. If a spark jumps to it, you will the next time… if there is a next time. And, some late model cars have the battery under the back seat (Bonneville is one) with pos/neg posts under the hood for jumping. In this case, hook up to those. I’ve seen many posts say, “I’ve done it this way…”. Well, many smoke while filling up but it only will take one time. Be safe.

28 Andy August 30, 2012 at 8:43 pm

Great how-to! And for all the doubters who say hook up black first, look at Josh’s nice explanation 3 comments up. His explanation is dead on.

29 Bucky September 4, 2012 at 7:17 pm

@Josh, your first 2 explanations were great. The 3rd one, though, is not the reason. The reason that you connect the negatives last, is so that you can make the final connection to the chassis instead of the battery post to have the spark be away from the battery. If you connected positives last, your last connection has to be on the battery post, which would risk an explosion if there was a gas leak. (Only the negative terminal is connected to the chassis).

30 Sander September 8, 2012 at 3:02 pm

I had to jumpstart my ’99 Z28 last night after doing some work on it. The lable on the jumpercable described the steps just as in this this article, except for hooking the negative to the body. But I can see this does prevent an explosion in some situations.

Regards,
Sander, The Netherlands.

31 JeffC September 9, 2012 at 10:35 pm

I apologize for the long post…

@ Jason (post #25) — Yes, leave everything connected until both cars are running, then disconnect.

If you receive a jump, you should always get to the bottom of it, and determine why you needed a jump. If you have an older car and just left the lights on (maybe a rainy day, when it’s just easy to jump out of the car and walk away), it’s easy to know: you let the battery drain, and your electrical system is probably fine. But if there is no obvious reason, some trouble-shooting is in order.

Corrosion on battery cable/terminal connection, and/or loose cable connection? This is very common, and I always at least try to test the tightness of the cable/terminal attachment by trying to twist the cables on the battery posts: if I can move the cable, it’s loose, and that’s likely my problem. If I don’t have tools with me, I’ll try to twist and push them down on the post to try to get the best connection I can, and clean and re-attach them when I get home, which costs nothing but some time.

Any time I receive a jump I always check the date on my battery: this should be recorded in the glove box for easy reference, but it’s easy to forget how much life is still left in them: if it’s close to the “expiration date”, it’s time for a new battery, because this one is close to the grave. In my experience, they usually fail uncannily close to their expiration dates.

Driving the jumped car for 20–30 min. after it starts allows the alternator to begin charging the battery again to the point where it can reliably start the engine on its own. I ensure my battery is sufficiently recharged by driving for 20 min., and when I have a bit of open road ahead of me, slipping the transmission into neutral, shutting off the engine, then trying to start the engine while I’m moving along at at least 30 mph. If the car starts, I go home; if it doesn’t, I bump-start the car on the fly by leaving the key in the “On” position, slipping the transmission into a high gear, and releasing the clutch. (Never remove the key from the steering column of a moving car: the steering lock will engage at the slightest movement of the wheel, and you will have no steering control). If after 45 min. and several attempts go by, and the battery still cannot start the car, at least it’s still running, and I head to the shop, because either the battery will not accept a charge, the alternator is not generating current, or the regulator is not allowing the current produced by the alternator to get to the battery. In any case, it needs a mechanic with diagnostic tools. This ability to bump-start a moving car is an advantage of the manual transmission: it cannot be performed with an automatic transmission.

If I had a car with an automatic transmission, I’d drive straight to my mechanic’s shop (make it at least a 20-min. drive), and try the independent start there. Pull all the way in: no sense driving all that way just to have it fail to start on the curb. That way, if it fails, you’re already at the shop and have avoided a tow.

Of course, a AAA card is probably the most valuable tool to carry in your car. I mean, if you want to depend on other people on some rainy night. :)

In response to post #10, I’ve never heard of a car that won’t allow the alternator to charge the battery if the light switch is not turned to “On.” If any car were built this way, and you only used your car during the daytime, you’d have a flat battery eventually: even if the alternator is supplying all the electricity needed for the ignition system, the battery would still have to supply power for starting the engine and for accessories like radio, etc. There must be some misunderstanding there.

32 Tony April 26, 2013 at 1:53 pm

In as much as i know about cars, i never in my wildest dreams thought of jumperig a dead car battery the way you displayed the proccess here. Glad i visited. Got to pass on this info to my friends and have them check it out themselves. Keep it up.

33 Amanda December 6, 2013 at 10:05 am

This is a pretty handy primer for people who don’t know what they’re doing, but the comments have been even more insightful. I’ve never paid attention to my jewelry when jumping the car, but that’s a great tip!

34 Dylan January 29, 2014 at 2:48 pm

Just a quick point to make, some cars don’t have labeled terminals, so if you don’t know which is which, this trick will help. The positive terminal is always the bigger terminal.

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