Running in full charge mode continuously can kill an alternator, so trying to have your new alternator try and charge your dead battery can result in immediate alternator failure.

about two hours

Alternators have moving parts, get dirty and are subject to stress from heat and cold. As a result, the internal parts gradually wear out. One of the most common failures is bearing failure. The needle bearings that allow the rotor to spin freely inside the stator can break down from dirt and heat.

Other reasons causing overcharging Bad Alternator: An alternator that’s not providing enough voltage will eventually kill your battery. But it’s also possible for an alternator to overcharge. It may be the wrong alternator has been fitted, or it is providing too much voltage. Both problems can overcharge the battery.

If it is left for weeks whilst discharged, it will chemically destroy itself. Just a month without charging (by running the car or with an external charger), this will reduce the life, a few months can ruin it, and a year..

In addition to mitigating the effects of external factors like heat, vibration, and contaminants, you can also prolong the life on an alternator by replacing certain components before they wear out. For instance, some manufacturers recommend that you check the regulator and brushes every 12 to 24 months.

The Do Nots of the Alternator Your car will just not start. Some people believe that you can just tap the alternator with a hammer to get it to operate. You should not do this because it will damage the part and you might even damage the surrounding parts to the car, resulting is a large car repair bill.

How To Jumpstart A Car With A Bad Alternator

1. Find Someone with a Good Battery. You can’t jumpstart a dead battery without a fully-charged option at your fingertips.
2. Let It Run. Before the jumpstart begins, you’ll want to run the other engine for 3 to 4 minutes.
3. Turn Accessories Off.
4. Get Thee to a Mechanic.
5. Use a Jumper Pack.