Sooner or later, the day will come. Probably when you least expect it. You’ll sit in your car, turn on the ignition, and then… nothing. Your car won’t start. Maybe your battery is getting old, or maybe you left the lights on and it got drained. Whichever the case, here’s how you can jump start a battery and get your vehicle back on the road. But first…
Table of Contents
- 1 A word of caution
- 2 Things you need
- 3 Getting ready
- 4 Let’s get started!
- 5 How to connect jumper cables
- 6 Jump start your battery
- 7 Troubleshooting
- 8 Disconnecting the cables
- 9 Last steps
- 10 Alternative #1: Using a portable jump starter
- 11 Alternative #2: Push starting (bump starting)
- 12 Alternative #3: Cigarette lighter jump starter
- 13 Alternative #4: AA batteries
A word of caution
Battery explosions do occur. On the inside, a car battery contains a series of 6 lead plates submerged in sulfuric acid, so when lead and acid react electricity is generated. A byproduct of this reaction is hydrogen, which also accumulates when charging a battery. Hydrogen is highly flammable. Rocket engines are powered by it.
While connecting jumper cables or charging the battery, sparks may form, which can ignite hydrogen and cause an explosion. These explosions have been described as
“being nearly as loud as a gunshot, as the plastic case blows apart – followed by the sound of toxic, highly concentrated sulfuric acid bubbling to the ground.” (excerpt from the L.A. Times)
It’s dangerous stuff. On top of that, electricity can be a risk by itself. Although your body is not conductive enough to be electrocuted by 12 volts, a car battery can still deliver several hundred amps, more than enough to cause an electrical burn. Also, handling the jumper cables can be risky if you are wearing a pacemaker.
There are several precautions you should have. In this article, we’ll go through the steps you must perform when jump starting a car and the safety measures you should take.
This strategy may not work…
Things you need
– A second car with a good, running battery. This is your booster car.
Caution: if any of the cars you’re using is an alternatively fueled vehicle, or has an electronic ignition system, it may get damaged from the use of jumper cables. Check your car’s manual and if you are in doubt, go to a repair center for specific advice.
– Jumper cables.
If you are reading this because you need to jump your car right now, and you’ve already got your jumper cables, the following advice may seem futile, but it’s still good that you know: the kind of jumper cables you use really does matter.
Thicker cables have a bigger load carrying capacity (ampacity, defined as the current carrying capability of a wire), so, keeping everything else equal, thinner cables will take much longer to charge your battery, or under certain conditions, such as extreme cold, they might not get you there at all.
Thinner (cheap bad) cables can even burn while performing a jump start, if they aren’t handled properly.
The gauge of a jumper cable denotes its thickness. The lower the gauge, the thicker the cable. 10 is too thin, 8 might be sufficient, 6 is best. Unless you are jumping a semi-truck, 4 is probably more than you’ll need.
Look for sturdy clamps, and if they have teeth (crocodile clips), even better. That way you can be sure the clamps won’t slip off the battery terminals while you are performing the jump start.
– Protective glasses and gloves.
Alright, this might seem a bit too much for some, but if you’ve got them, use them. And if you don’t have them, you should. Remember sparks and explosions, so why risk it?
– A cleaning cloth, or better yet, a battery terminal brush.
This doesn’t get mentioned enough. You’ll see why you might need it in the next sections.
Getting ready
● Don’t smoke while attempting to jump start your battery. Avoid any possible source of flames.
● Do not attempt this in a confined environment. Find an open, well ventilated space.
● Check your clothing. Are you wearing loose sleeves, bracelets, a neck chain? Remove anything that might get caught in the plethora of hoses, housings, wires and moving parts that’s under your car’s hood. Remove anything metallic that might accidentally touch the jumper cables or battery terminals.
● Take a moment to check your car’s manual and see if there are any special instructions. Some vehicles may require extra steps in order to jump start the battery successfully.
● Check that your jumper cables are in good condition. There should be no exposed wire along the length of the cable. The rubber coating should be free of cracks or peeled areas.
● Check that the clamps of the jumper cables are clean. Dirt,dust, grease, moisture or any other contaminants might interfere with the jumper cable/battery connection. If you see any dirt, get rid of it using your brush or cleaning cloth.
● If you have small children or pets, make sure they are in a safe area, away from the cars while you perform the following steps.
Let’s get started!
1) Park the “booster“ car next or in front of the stalled car. They should be close in order to allow the jumper cables to reach both batteries, but make sure that they are separated and never touch each other.
2) Set the gear in neutral (for manual transmission cars) or park (for automatic cars) for both cars.
3) You don’t want the cars accidentally moving while jumping the battery. Set the parking brakes on both.
4) Make sure that you turn off the lights, air conditioner, radio, and anything else that might drain the battery of the stalled car. Shut off the ignition and remove the keys from both cars.
5) Open the hoods of both cars to access the battery. Note that, in some vehicles, the battery could be located in the trunk (check your car’s manual).
6) Visual check: inspect each vehicle’s battery.
- If the dead battery looks damaged, cracked, or if by any chance it is leaking, do not attempt to jump start it. It is dangerous, you might cause an explosion, and it is probably best to replace it. Have it checked by a qualified professional.
- It’s highly unlikely, but, if the “good” battery is leaking, damaged or cracked, get another booster car to perform the jump start. If that’s not possible, see the alternative methods described below. Get the battery checked by a qualified professional.
- Dirty battery posts and cables are cited as the most common cause of battery explosions upon engine start up. If any of the battery terminals look dirty, clean them using a brush or cloth, just like you did with the clamps of the jumper cables.
- If the dirt actually looks more like corrosion (salty crust around the battery and wiring), it might be more difficult to get rid of. Here’s what you can do.
- Avoid simultaneously touching the two terminals, and remember you should be wearing gloves.
All good so far? Alright, here comes the tricky bit…
How to connect jumper cables
There’s a proper way to connect the jumper cables in order to minimize the chances of creating sparks close to the battery. Please do not rush while following these steps.
7) Identify where the positive and negative terminals are in each battery. Normally, battery posts will have caps on them, one red and one black, although they could have different colors. Red is positive, black is negative. They could also be labeled + and -. Remove the caps.
We’ll check for further markings, just to make sure that the caps haven’t been misplaced. Positive posts are usually larger in diameter. They could also be labeled +, POS, or POSITIVE. Negative terminals will be labeled with – , NEG, or NEGATIVE signs. These signs can embossed next to, below or above each of the terminals, and sometimes they will not be immediately visible.
Colors for positive and negative terminals may be different, and markings may not be readily visible, but they should be there. In this case, look for them and you will see the + and – signs next to the caps.
If in doubt, look for the cables coming out of the battery and follow them back to their source. The black cable should be connected to your car’s chassis. That’s your negative. The red cable should go to your car’s starter and alternator. That’s your positive.
Note: Modern vehicles are negative grounded, as described above. In the rare case that you are trying to jump start a classic car, and old tractor, or some other vehicle from the 60´s or older, there’s a chance that you might have a positive grounded vehicle. It can be done, but as there are variables specific to your situation that you need to keep in check (for instance, is your battery 6 or 12 V?), my advice would be to consult with a professional if you are unsure about what you are doing. Safety first.
8) Take your jumper cables and spread them out. Detangle them if necessary. Re-check that the clamps are clean. You are about to connect the first clamp, and from this point forward, we don’t want the ends of the jumper cables touching each other, in order to avoid shorting the circuit.
Also, from now on, manipulate the jumper cable clamps only through the rubber coatings, and make sure you don’t, by any chance, touch the metallic ends of the jumper cables.
9) Go to the dead battery. Since it’s currently storing less energy than the good battery, starting here is safest. Attach the red, positive clamp to the positive terminal of the battery.
Make sure that the copper pieces of the clamp are directly touching the metal of the battery terminal. You can wiggle it around a little bit to make sure you’ve got a solid connection.
10) Most of the time, red and black jumper cables are attached to each other. You are about to go over the booster car, but before you do that, you shouldn’t leave the black clamp just laying around. It can’t be in contact with metal.
You can find a plastic surface inside the hood and leave it resting there. Make sure it won’t move. Or you can have a second person to hold it carefully.
11) Go over to the booster car. Attach the other end of the red cable to the positive terminal of the good battery. Just like before, make sure it’s properly connected.
12) Still at the good battery, connect the black, negative clamp to the negative terminal. Check that you’ve got a good connection.
13) Just one clamp left. You might be tempted to go over to the dead battery and attach it to the negative terminal. Don’t. That could create a spark right above the battery, either when you connect the clamp, or later when you are jump starting the car.
Some cars have a grounding spot away from the battery, specifically for jump starting. Sometimes it’s called jump starting pole. This should be in your car owner’s manual.
If there’s no specific grounding spot, find an unpainted piece of metal that’s as far away from the battery as possible, that isn’t a moving part and that isn’t attached to any electrical or fuel components. Three good spots are usually:
a) the metal strut that holds the hood open
b) a heavy gauge metal part of the frame
c) a nut in the engine block (but please make sure you choose a spot away from the fuel pressure regulator)
When you are done, you should have something like this:
In this diagram, the stalled car is in red, and the booster car is in green. Numbers indicate the order in which you must connect the clamps. 4 is the grounding spot/jump starting pole.
14) Almost ready. You still need to do one more thing before starting the engine. All the cables are set up, but you still want to make sure that they are away from any moving parts such as belts or cooling fans, as they might get caught and damaged when the engine starts running. Check both cars.
Jump start your battery
15) Start the engine of the booster car. You should leave it running in order to allow the stalled battery to be charged. How long you charge your battery for will depend on why it lost its charge in the first place:
a) The lifespan of a car battery should be somewhere between 2 and 5 years. If your battery is relatively new, and it got drained because you left your lights on for an extended period, charging for 1-2 minutes should be enough.
b) If your battery is older, or your car hasn’t been started for a month or more, charging could take longer. Wait 5 minutes before going to the next step.
16) Go to the stalled car, put the keys on the ignition, and attempt to start the engine. You should be up and running! If not, try these:
Troubleshooting
● Can you hear the engine cranking slowly, but it just doesn’t get started? Your battery might still need some extra charge. Take the keys out of the ignition of the stalled car, let the booster car run for another 5 minutes, and try again.
● If it seems like you are really close to starting, but you need a little bit more juice, have another person in the booster car rev up the engine to about 2000 RPMs (just the engine, do not move the car!). Hold it there while you try to start the vehicle with the dead battery. This will get the alternator (which is charging your battery) spinning faster, so you will have more power to start the car with the dead battery.
● If your car doesn’t start, but it does crank quickly, check your gasoline level.
● If after all the previous steps, all you get is a click, but you can’t start your engine, your battery may be shorted internally, or your car may have other electrical problems besides the battery. But, before you give up,
- Re-check that you’ve got a good connection on the positive and negative terminals. Check the good battery and the dead battery.
- Try connecting the black jumper cable to a different grounding spot on the stalled car. Sometimes switching the ground will do the trick.
If all of the above fails, the problem could be a faulty alternator, fuses, the ignition switch or some other component. It’s best that you have your car checked by a qualified professional.
Disconnecting the cables
Hopefully, your car is finally back to life. Stop the booster car. Leave the engine of the formerly stalled car running so the battery can replenish its charge. You are about to disconnect the jumper cables, reversing the previous sequence.
17) Remove the black, negative clamp from the formerly stalled car. Be careful. Your cables are still live, running electricity, so do not let this clamp touch anything.
18) Remove the black, negative clamp from the booster battery.
19) Remove the red, positive clamp from the booster battery.
20) Remove the red, positive clamp from the formerly dead battery.
Last steps
21) Carefully, put the caps back on the battery terminals, one at a time.
22) Close the hoods of both cars.
23) You can take off those protective glasses now (and the gloves too!)…
You are not stranded anymore, and your car is running and ready to go. Good job!
Now you just have to charge your battery a bit more, to ensure it won’t die off next time. Driving your car for 20 -30 minutes will do. However, if your battery is 4 years old or more, you should consider having it replaced.
It wasn’t that hard after all, right? In the dire case that you don’t have access to a second car or jumper cables, or you just feel adventurous and want to try something different, here are some good – and not so good – options you could explore.
Alternative #1: Using a portable jump starter
Having a portable jump starter at hand can certainly make things easier. You don’t need a second car to revive your dead battery. Most modern jump starters are small, so they can be unobtrusively stored in your car trunk.
Many jump starters will have a led light that indicates when your battery has enough charge to start the car. Downside is – you have to make sure you keep them charged periodically, or you could find yourself with a dead battery and a dead jump starter.
As all models are different, make sure you read your jump starter’s manual before attempting to jump start your car. Here’s the outline of the steps you should follow:
● Go through all the precautions and preliminary checks described above (Getting ready section and steps 2 through 8).
● Make sure your jump starter is in the off position.
● Take your red jumper cable and connect it to the positive terminal of the battery.
● Since your jump-starter is still in the off position, there is no electrical current going through the cables, so there is no risk of sparking. Connecting the black jumper cable to the negative terminal of the battery is a common practice when using portable jump starters, but I’d strongly advise you not to do this. Although chances are slim, sparking could still occur while charging your battery. The best practice is to connect the black jumper cable to a metallic grounding spot away from the battery (step 14).
● Check the connections on both terminals.
● Turn on the jump starter. If it has a led indicator, wait until it turns on.
● Try to start your car. If it doesn’t work immediately, do not crank the engine for more than 5 seconds. The jump starter will deliver its maximum current when you attempt to start the engine, and it is designed to do so only in short bursts. Wait 2-3 minutes before trying again.
● When your engine starts, switch your jump-starter to the off position.
● Allow the jump-starter to cool for a few minutes. If you have a lithium battery- powered jump starter, it is advisable that you recharge it as soon as you can. Even if there is still plenty of charge in the device, maximum battery lifespan can be obtained if it’s kept as close to fully charged as possible.
Alternative #2: Push starting (bump starting)
If you have a car with manual transmission, you can drive it down a slope, or have a few friends or friendly strangers to push it while you try to get the engine started (preferably both).
Photo Credit: Marina del Castell
Be sure to check your car’s manual before attempting this, as certain manufacturers explicitly advise against bump starting some car models, due to potential damage to the catalytic converter.
Please note that most vehicles with automatic transmission cannot be push started. What we are doing here is getting the engine moving through the rolling of the wheels of the car. In an automatic car, the hydraulic torque converter in the transmission will not allow the engine to be driven by the wheels.
Here’s how it goes:
● Get your car in place. Ideally, you should have a clear and long stretch to go down or be pushed through. The faster you can go, the more momentum you can build up, the more likely it is that you can successfully bump start your car.
● Make sure all electrical equipment is turned off.
● Fully depress the clutch and select *second* gear (see note below).
● Get your car ready to run. Turn on the ignition and disengage the brake.
● Get moving!
● Ideally, you should reach 5 -10 mph (8 to 16 km/hour), and then release the clutch.Releasing the clutch as you normally would when driving should get the car started. If you do it too quickly, you might make your car jolt. If you do it too slowly, the car won’t start.
● When you hear the engine running, depress the clutch and press the accelerator slightly. Depressing the clutch will prevent the car from stalling again if you are running at a low speed. Pressing the accelerator slightly will enable the alternator to charge the battery.
● Drive for 20-30 minutes to allow the battery to be replenished.
Which gear should I use?
General rule is, the faster you are able to roll the car, the higher the gear you should select. You could damage your car’s transmission if you use an improper gear.
Second gear will usually do the trick if you can get the car moving to 5-10 mph. If you can’t have the car pushed this fast (heavy vehicle, just one or two persons pushing, short distance to push through), use first gear to have a better chance of starting the car. Or, you could try it in reverse, pushing the car backwards, since this usually requires less speed to get the car started.
If you run down a hill, you should use third or fourth gear.
Alternative #3: Cigarette lighter jump starter
This option is not really recommended, since you need plenty of time, and it might not work at all. Cigarette lighter jump starters are cables that you can plug at the cigarette lighter socket in your car. These sockets are actually 12 volt power outlets connected to your car’s battery. So, you connect your stalled car to a car with a good battery using a cigarette lighter jump starter, and you can slowly recharge your battery. While this sounds far simpler (and safer) than manipulating your car’s battery, there are many drawbacks:
– These are thin wires, and they cannot deliver the same amount of current as you would using good jumper cables.
– The amount of current available through the sockets is small. Cigarette lighters are typically fused at around 10 A.
– Cranking the engine can require upwards of 350 A. Considering all of the above, you can’t provide an actual “jump” using a cigarette lighter jump starter.
In theory, what you do here is provide the dead battery with a weak charge, which, over time, may be enough for the engine to start. But you’ll be better off using any of the methods described previously. There’s some further reading here and here, in case you are interested.
Alternative #4: AA batteries
Okay, let me make clear that I’m not recommending that you do this. At all. It’s difficult, impractical, and possibly dangerous. Watching the video, though, is actually quite funny. Hook 12 AA batteries together in series, connect them to your car’s battery for 10 minutes, and you should have enough juice to start your engine. If it only were that easy…
Here’s the video by youtuber ElectroBoom (scary name, uh?). Some further analysis here.
I sincerely hope you found this post useful. Happy rides!