How Long to Run a Car After a Dead Battery

If you have a dead battery and jump-started your car, you might wonder how long you’ll run it.

It is necessary to keep a car running after jump-starting to charge its battery for at least a few minutes. But this is only to start the car, not to charge its battery fully. So how long should you run the car for?

After jump-starting a dead battery, you should let the car run for at least an hour or drive it for at least half an hour. I recommend a couple of hours to achieve an 80% charge or drive it up to an hour to charge it fully.

Also, be aware that (lead-acid) car batteries usually have a lifetime of up to 3 or 4 years. If you need to jump-start often, you might have to replace the battery. I’ve also mentioned some signs of a dead battery to look out for.

How Long to Run or Drive the Car

car approaching
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Letting the car run for at least half an hour is normally sufficient for the alternator to charge a dead battery completely or sufficiently.

If you run the car idle, you must run it for a couple of hours to charge it up to 80% or at least an hour to get started.

But if you drive the car, you can get it charged sooner. It normally takes an alternator between 30 minutes to an hour to charge the battery fully, so it would take less than half the time.

man jump-starting a car

You could increase the engine’s RPM by stepping on the gas pedal while stationary to make the battery get charged quicker, i.e., without driving the car, but that would not be good for the engine.

So you can certainly charge a car’s battery by letting the engine run idle but driving it will allow you to accomplish it quicker.

Signs of a Dying Battery

car engine battery
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You should know the signs of a dead battery because you’ll know you must run or drive the car for at least half an hour.

Slow or Late Start

If the car is slow in starting, starts late, or the engine is slowing or not turning at all, it might be due to a weak battery or a faulty alternator.

But you might be able to push-start the car if it’s a manual transmission.

Dim Lights

Headlights dimmer than normal or flickering frequently are another sign of insufficient battery power.

Dysfunctional Devices

Like dim lights, dysfunctional devices could also be due to a weak or failing battery.

Engine Light

A check engine light indicates a problem with the engine.

It might be as simple as a loose cap, but it could also be due to a dying battery. When the check engine light comes on, a clicking noise may confirm that you need to replace the battery.

Worn Out Connectors or Cables

All cables and connectors wear out over time.

It can lead to corrosion on the battery’s terminals, obstructing current flow. It could be due to battery leakage. Always keep the connectors and terminals clean and all cables connected to them in working order.

Pungent Odor

If you notice a pungent odor, it might be due to a leaking battery.

The odor is due to the sulfuric acid, and the leakage could result from overcharging. Avoid overcharging when charging the battery externally.


How Car’s Engine Works.

Jump-starting a Car:

Video References

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About Alex Robertson

c3c9d43f1f0d14c4b73cb686f2c81c4e?s=90&d=mm&r=gCertifications: B.M.E.
Education: University Of Denver - Mechanical Engineering
Lives In: Denver Colorado

Hi, I’m Alex! I’m a co-founder, content strategist, and writer and a close friend of our co-owner, Sam Orlovsky. I received my Bachelor of Mechanical Engineering (B.M.E.) degree from Denver, where we studied together. My passion for technical and creative writing has led me to help Sam with this project.

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