Can you jumpstart a car with a bad alternator?

You can jump start a car with a bad alternator, but then what?

Yes, you can jumpstart a car with a bad alternator in the dead car.

NEW TYC alternator

It’ll most likely start. But depending on exactly what’s wrong with the alternator, it might continue running once you remove the jumper cables.

How to jumpstart a vehicle with a bad alternator

The battery in the dead vehicle is going to be very discharged. So keep the jumper cables on the dead vehicle for at least 15 minutes before you try starting it. That way, the battery will have some juice to keep running after you disconnect the cables.

What to do after you jumpstart a car with a bad alternator

If the alternator is completely dead

You may be able to move the vehicle a few feet or maybe even a block. But with no recharging going on, the only power the battery will have is the small amount it got during the jumpstart. Your best bet is to get it to a safe place while making sure it doesn’t quit in the middle of the road as you try and move it.

If the alternator is charging a little

Turn off all your electrical accessories to preserve power and lighten the load on the alternator. That means no blower motor, defogger, heated seats or even the radio. You are in bare bones mode.

Don’t idle for long periods; an alternator can’t put out more than 1/3 of it’s maximum capacity at idle speed. If you’re at a stop, increase your RPMs to around 1,500 to keep charging the battery.

If your alternator light is on (which it should be if your alternator is bad), you need to get where you’re going in a hurry. You won’t have much power left.

If your alternator light isn’t on, drive for at least 20-minutes before shutting it off. It takes a while to recharge a battery. It takes a lot of power to run a late model vehicle. See this post on how much power a car needs

Jumpstarting with a bad alternator isn’t really a permanent fix

Jumpstarting a car with a bad alternator is a temporary solution and should not be relied upon for long-term use. Get it to a shop ASAP.

©, 2023 Rick Muscoplat