How Long Should You Run Your Car After a Jump Start?
Short answer: drive it for at least 20 to 30 minutes, ideally at steady road speeds, and then get the battery tested. Here is why, and what changes in a Colorado winter.
The short version
- Aim for 20 to 30 minutes of driving, not idling. A drive on a highway or at steady speeds charges better than stop-and-go.
- Do not shut the car off in the first few minutes after the jump, because it may not restart.
- Get the battery tested the same day if you can. Many auto parts stores test batteries and charging systems, often for free.
Why idling is not enough
The alternator charges the battery and runs the car at the same time. At idle, it makes less power, and the car's own systems (lights, heater, fans, defrost) use most of it. Very little is left to refill a flat battery. Driving at higher engine speed gives the alternator more to work with.
Why even 30 minutes may not fully recharge it
A battery that has been drained all the way down is damaged a little each time, and a short drive restores only part of its charge. A full charge can take several hours on a proper battery charger. If you can, put the car on a charger overnight after a bad drain. If the battery is more than three or four years old, a jump is often a warning that it is near the end of its life.
Cold weather makes it harder
In winter, the heater, seat heaters, rear defrost, and wipers all draw power, while a cold battery accepts a charge more slowly. On a freezing morning, turn off accessories you do not need for the first part of the drive. If you only make short trips in winter, the battery may never get back to full charge. See why cars will not start in cold weather for more.
What if it dies again?
- It dies again after a short stop: the battery probably will not hold a charge. It needs replacing.
- It dies while driving, or warning lights come on: the alternator or a belt may be failing. Pull over safely and call for help.
- It starts fine for a day, then dies again: something may be draining the battery when the car is off, such as a light, a failing module, or an aftermarket device. A shop can test for a parasitic drain.
Quick checklist after a jump
- Remove the cables in reverse order and keep the clamps from touching.
- Leave the car running and drive for 20 to 30 minutes.
- Turn off extras (heated seats, rear defrost) if the weather allows.
- Have the battery and alternator tested.
- Replace the battery if it fails the test. Keep a charged jump pack in the car for next time.
New to jumping? Start with our guide to jump-starting a car safely.
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See membership plansSign up freeCommon questions
How long should I drive after a jump start?
Plan on at least 20 to 30 minutes of driving, preferably at steady road speeds rather than idling, and get the battery tested soon after.
Is idling enough to charge a battery after a jump?
Idling charges a battery very slowly, because the alternator makes less power at idle and the car's systems use much of it. Driving is more effective.
Why did my car die again after a jump start?
The battery may be too old to hold a charge, the alternator may not be charging, or something may be draining the battery when the car is off. A battery and charging-system test can tell which.