Many people aren’t sure how they should go about jumpstarting a car that has a depleted battery. I have to do it from time to time because I have an old car that I don’t use much, so I’ll explain how to do it, and share some tips that could save time and money in the future. Make sure that you read the safety bits too.
You’ll need
- a set of jumper cables (longer can be more convenient ~$13 (12-ft) or ~21 (20-ft)). For high-amperages, make sure that you get cables thick enough
- a charged battery (another car, or a portable battery ~$72 – ~$80).
General procedure
Beware: Hybrid/electric vehicles may not be compatible with classic jumping techniques, so refer to your user manual, or contact the car manufacturer. Toyota explicitly says that a Prius should NOT be used to jump start another car. Here is an interesting thread that discusses the topic. Cars with an electronic ignition system
Safety (read this!)
- Put the cables nearby, making sure the connectors/clamps don’t touch one another
- Unplug any electric devices that may be plugged in the cigarette lighter
- Turn OFF radio, lights, and other electric-powered car elements
- Make sure that both cars are parked in neutral with engines OFF
- Cars should not touch each other
- Engage parking brakes for both cars, remove the keys
- If the battery is cracked, replace it. Do NOT attempt to charge it as it may explode
- Wear eye protection if possible
- It’s easier with two people, but I’ve done it myself many times
Jump start your car in 6 easy steps:
If the battery connectors are very dirty, brush or wipe gently. Remember that in general, the Red cable is meant to connect to the Positive (+), and the Black cable goes to the Negative (-) our ground.
Also make sure that the clamps are well connected and that a mobile battery pack won’t fall over when the car starts. Cables should not be near moving parts as well.
- Connect red clamp to Drained Battery (+/Red) terminal
- Connect remaining red clamp to Charged Battery (+/Red ) terminal
- Connect black clamp to Charged Battery (-/Black) terminal
- Connect remaining black clamp to Drained car unpainted surface around the engine block*
- Start the working vehicle**
- Start the vehicle with the Drained battery. It should start.
- Once the vehicle with the Drained battery runs, leave it running as the drained battery is now being charged by its alternator.
- You can leave both cars running side by side for ~2mn before disconnecting
- Disconnect the cables in the REVERSE ORDER, without letting the clamps touch one another, or anything else: there is live current going.
- It’s better to leave the car running for 15-20 mns before turning it off again. The more you drive, and the more the battery will recharge.
*Step 4 additional information: This is to avoid igniting battery fumes, if present. Some cars have a dedicated spot for that marked as Ground/Gnd
**Step 5 additional information: This will avoid draining a weak, but working, rescue battery
I found a video from Edmunds that illustrates the different steps:
Tip: use a portable battery
The above steps work, but of course, the main caveat is to have a car available. You can ask for friends or neighbors, but when you are stuck at the airport or something like that, the options are limited. You may end up calling a help service which will cost you ~$100+ just to jump-start your battery that one time.
Instead, I prefer using a portable battery (mine is similar to this $80 one). I used to think of them as being those huge, cumbersome, expensive and mostly useless batteries, but modern ones are small and can be used to charge my phone and tablet. They can also turn into a large-capacity flashlight, which is also handy while on the road.
Most come with an external charger, but I recommend opting for a USB-chargeable one because you don’t have to lug around the charger and you can recharge it whenever. I have one in my car and it replaces the flashlight I used to have.
If you have a truck or a car that require a high amperage, you may need to check that the battery pack will be enough. For regular-size cars, 500A is usually sufficient. Now I can pick up my car at the long-term parking late at night and not worry about getting stranded until someone helps me out.
What if it didn’t work?
If jumping using the above procedure didn’t work, you may have another issue which is not battery related. First, it would be worth seeing if the vehicle’s light work or if theirs is an issue with the ignition (switch, electric wiring). Or maybe a fuse or more need replacing.
Try making sure that the connections are clean, but if things still don’t work, you probably have a bigger problem than just a dead battery.
Also, if your battery tends to become discharged after just a few days, it may need to be replaced. These are not meant to last forever.
Conclusion
At the very least, I recommend having some jumper cables in your trunk. The longer, the better. I’ve been in situations where we could only park cars side by side and not facing one another. You never know what odd places you may need to jumpstart your car in. Spend the extra $10 and get 10 more feet of jump cables – thank me later in the comments.
Alternatively, the mobile battery works great and lets you fix things yourself, and right away. Calling a repair service will be longer and become a steep one-time expense.
Filed in . Read more about Cars.