Being stuck with a faulty alternator and a dead battery is frustrating. But can you get your car moving again by jumpstarting your vehicle even though the alternator is not charging your battery?
This article outlines the steps and risks involved to jumpstart your car for at least temporary power to the most important systems of the vehicle, to enable you to drive your car to a mechanic and get the alternator fixed or replaced.
While jumpstarting a car with a bad alternator could be possible, I do not suggest connecting jumper cables between vehicles any longer than necessary, as it could damage delicate electronics. See here for more information.
How To Successfully Jumpstart A Car With A Bad Alternator
If you have a faulty alternator and need a jump, here are five steps for getting your vehicle going; just be very careful with your power as you try to get to the nearest repair shop.
Without a working alternator, your battery will have very little amount of time before it runs out completely. So, rather than sitting in someone’s driveway or a parking lot, you could be sitting on the side of the road.
#1. Get A Jumpstart from A Good Battery.
The first bit of advice is pretty obvious. If you need a jumpstart and have a bad alternator, make sure the other vehicle battery is in good shape and has a full charge.
The reason is that your battery is going to be drawing a lot more current from this other battery than it normally would when you go to jumpstart your vehicle.
Optional: If you have a portable jump starter (such as the Stanley J5C09 or NOCO GB20) in the trunk, this could be another way to jump-start your vehicle, or at least give you a second jump-start if you do not make it the first time around.
These portable jump starter boxes are good, cheap insurance to have, especially since you do not need to find someone willing to help you.
#2. Connect Jump Cables.
- Attach one red clamp to the positive (+) terminal on the dead battery.
- Attach the other red clamp to the positive (+) terminal on the good battery.
- Attach one black clamp to the negative (-) terminal on the good battery.
- Attach the other black clamp to an unpainted metal part (nut, stud, bolt head, or bracket) in the engine bay of the car with the dead battery. This will be a proper ground.
#3. Let the Other Car Run for 4 Minutes.
When the jumper cables are all connected, have the owner of the donor car (good battery) start their vehicle. The car with the dead battery has to be turned off.
After roughly 3-4 minutes, attempt to start your vehicle, which has a dead battery and a bad alternator. If the car cranks a bit but doesn’t start, wait another 3 minutes and try again.
#4. Keep the Accessories Turned Off.
After you start jumping your battery, regardless of whether it gets enough power to start, make sure all of the car’s electronic accessories are turned off.
This includes turning off the heating, air conditioning, the radio, CD player, GPS, phone charger, or whatever else you generally use in your vehicle to draw power from the battery.
You are going to want to conserve as much battery power as possible so that it can power the necessary parts.
It is worth mentioning that you are only going to want to do this during the day and when it is dry. If you need your headlights or windshield wipers, you may exceed the amount of battery power that you have.
#5. Drive Straight to the Mechanic.
If you are successful at jump-starting your vehicle from the other car’s good battery, then drive directly to the nearest mechanic. You likely have a good 5 minutes or so before the vehicle’s power shuts off.
Do not go on any major highways or traffic-congested roads. Only drive on the slow-moving streets of your current location.