How Long To Charge A Car Battery With Jumper Cables

If you’re wondering how long to charge a car battery with jumper cables, then you’ve found the right article. In this article, not only will you find out how long you can charge a car battery with jumper cables safely, but you’ll also find out what happens if you charge the car battery for too long and how to charge the car battery faster, and much more!

So keep reading to find out everything you want to know!

How Long To Charge A Car Battery With Jumper Cables?

You should only need to charge your battery for about 5 minutes once you’ve hooked up the jumper cables. If after 5 minutes it still won’t start, then you’re either jumping the battery wrong, or the battery just needs to be replaced.

However, that’s generally speaking. The answer to the question is actually a little bit more complex. If you have an older car, then 5 minutes is often more than enough, and in fact, you could probably get the car started before then. However, with more modern cars, it can often take a bit more time.

Modern cars take more time to start as the charging system often needs a minimum voltage to get going. When newer cars start, even if there’s power, they still need enough power to have full control over all the operations before they go.

How Long Does It Take To Charge A Dead Battery From Jumper Cables?

Just like with other batteries, a dead battery will need about 5 minutes before it will start working; however, the difference is that you should drive your car around for at least 15 minutes afterward to make sure the alternator is charging it enough.

Again, if a dead battery still doesn’t start after a few minutes, then it could be a sign that the battery just needs replacing.

Can You Charge A Spare Car Battery That’s Not Connected With Jumper Leads From Your Car Battery?

You may also be wondering if it’s possible to charge a second battery from your car battery, and the answer is yes! It’s possible; however, it’s definitely not the most efficient way of doing it. If you’re going to be driving anyway, you can hook up your second battery to the primary battery and then store it somewhere safe when you drive, which will result in both batteries charging simultaneously.

However, once you stop charging, the two batteries would continue sharing power which could result in both of them being partially charged but neither of them being charged enough.

A much more efficient solution would be to simply buy a battery charger and charge the second battery that way.

car battery clamped with red jumper cable to recharge the power

Can Leaving A Good Car Battery Attached To Jumper Cables Harm It?

If you are leaving a charged battery attached to jumper cables for too long, then it could definitely end up harming the battery. However, the answer really depends on what exactly is going on.

If the engine that houses the good battery is running, then both batteries will continue to charge; however, it’s unlikely it will receive a full charge. But this is only if the bad battery isn’t too depleted. If it is too depleted, then it will keep trying to take a continuous charge from the good vehicle’s alternator. While this will likely be unharmful to the good battery, it’s still slightly at risk.

BUT if you leave a flat battery connected to a good battery where no other charging is occurring, then the bad battery will continue to consume power from the good battery until they are both at an equal charge. However, when this happens, both batteries will just be partially charged, and it’s unlikely either will work. The only caveat to this is if the flat battery is flat because it’s dying. When this happens, the bad battery will continuously pull power from the good battery until it doesn’t have a good charge anymore.

So What Happens If You Leave Jumper Cables On For Too Long?

If you leave jumper cables on your batteries for too long, it could result in the battery becoming overcharged or permanent damage occurring to the battery or alternator. This is why it’s best to keep an eye on the battery when you’re jumping it and make sure you’re not doing it for more than 5-10 minutes.

A Few More Things To Remember When Jump Starting A Battery

As well as making sure you don’t keep your jumper cables on the batteries for too long, you should also remember the following.

  • Don’t jump-start a battery you already know is dead.
  • Don’t jump-start a battery that is cracked or leaking.
  • Make sure to wipe any corrosion off the battery before adding the jumper cables.
  • Don’t jump-start a frozen battery.
  • Make sure the battery has a good level of water before jumpstarting

Does Revving The Engine Charge The Battery Faster?

Revving the engine of your car WILL charge the battery faster. When you rev the engine, the crankshaft is going to turn faster, which in turn causes the belt of the alternator to turn faster, producing more energy. This is also one of the reasons it’s recommended to drive around for a while after you’ve jump-started your car.


As you can see, the jump start itself doesn’t tend to take that long to get the battery started. However, after the jump start, you should still drive for around 20 minutes to make sure the battery gets charged up enough. If you liked this article, make sure you check out the rest of the website! Otherwise, have a great day!

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