More Jump Starting Questions

Sometimes car batteries go flat without warning. In cold weather, car batteries produce less power and it also takes more power to get the engine started. This combination of problems can make it very difficult to start your car. The good news is that as long as the battery is still functional (so not frozen, for example), then you can get your car started if you can find a working battery or power source to ‘jump start’ the car.

Usually, jump starting a car involves connecting the dead car’s battery up to another car’s working battery, but you don’t have to use another car. Other power sources will work as well.

How to jump a car battery without another car

There are a few ways that you can jump start a car battery if you don’t have access to another car. If you have a manual car, then you can push-start it. This will get the engine running and get the alternator recharging the battery. Another option is to use a portable battery pack. Some people keep one in their car for emergencies, so that they can jump start their car if they get stuck in a remote location. There are handheld battery packs that are specifically designed to jump-start cars or provide your battery with a decent boost. These hold their charge for a surprisingly long time, and won’t take up a lot of space in your boot.

How to jump a car battery without cables

Usually, you would use jump leads to connect the two batteries together. If you don’t have jump leads, however, there may be another solution, as long as you have a manual car.

  • Find some people to help you push the car. You may be able to do this by yourself if you’re parked facing downhill, but if you’re parked facing uphill you will probably need several friends to push your car to get it moving.
  • Push in the clutch, keep it depressed, and put the car into second gear.
  • Still keeping the clutch held down, turn on the ignition.
  • Release the brakes, and have your friends start pushing the car.
  • Once you are moving, release the clutch, quickly.
  • With luck, the engine will start.

Once you’ve got the engine running, leave it running. This will slowly recharge the battery. Try to get where you need to go without stalling the engine! Be sure to recharge the battery properly (or replace it, if necessary) before you need to start the car again.

How to jumpstart a car battery with a battery pack

There are a few specialist products that will jump-start cars. You can buy battery packs such as the Jump Genie that will plug in to your car’s cigarette lighter and recharge the battery over a short period of time. These aren’t great for getting you to work in the morning if your car’s battery is flat, because they take about 40 minutes to give your battery enough charge to start the car. However, they will get you home on a night, so it’s worth having them as an emergency charge.

There are other portable power packs that can be connected directly to the battery’s terminals using crocodile clips. They connect to the positive terminal and an earthing point. Once the car has started, you simply remove the power pack and leave the engine running to recharge the battery.

Always be mindful of safety when trying to jumpstart a car using any form of battery pack:

  • Make sure that there are no tools or other metal objects nearby. Don’t rest tools on top of the battery/on the engine while you work!
  • Remove any jewellery while you are working on the car.
  • Take off any loose-fitting clothing that might otherwise get snagged in the engine.
  • Perform a visual inspection of both the ‘dead’ battery and the battery that you are using to jump start the car.
  • If you notice any signs of damage, on either battery, don’t try to perform a jump start.
  • Check the cables too. If the cables are damaged, try to source another pair. Damaged cables could short out, damaging your car or the battery. There is also the risk of electric shock, or fire.

After you start the car, leave it running for 15 minutes to charge up the battery. After that 15 minute wait you can drive the car as normal. Assuming the battery was not completely flat, it should have enough charge to start the engine again without needing a second jump start.

Can you jump a car with AA batteries?

If you want to try a Macguyver style stunt, then it is theoretically possible to start a car with AA batteries, but it would take a lot of time, and it requires a lot of batteries. It’s not really a practical solution!

AA batteries can put out a lot of energy, but they don’t do it as a burst of high current. The battery has its own resistance, and the more depleted the battery is, the greater that resistance gets.

You need 50A of current to run a car’s motor, and around 150A to get it to start in the first place. To produce the required 15V load, you would need to run 10 AA batteries in series. Those batteries would not produce the required amperage, however. To get that, you would need 100 of those strings of 10 batteries in parallel. So, you would need 1000 AA batteries to get the car started. That’s a best-case scenario, too, assuming that the batteries are fully charged and that they produce a steady level of power. That’s not how it really works.

In theory, given enough time and enough batteries, you could start a car with any power source – a truckload of watch batteries, or a large number of portable drill batteries, for example. The chances of someone being stranded with enough batteries to do this, and the wires required to link them all together, are slim, though. So, unless you work at a garage, have time to spare and want to show off with an elaborate party trick, this isn’t a solution you should rely on.

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