Can I use my alternator to recharge a discharged battery?

Using the alternator to charge a completely dead battery is definitely not proper procedure. It is highly recommended to use a stand-alone battery charger to recharge the battery before starting the car. Some professionals and home mechanics scoff at this, jump-start the car, and drive the car around the block to recharge the battery. They think that this will save them time, but they are only causing themselves more problems by shortening the life of the alternator and the battery.

An alternator’s purpose is to maintain the full battery charge after the initial start and provide enough power to run the vehicle’s accessories. These include the lighting systems, audio systems, and air conditioning. All of these items draw amperage from the system, and using the alternator to charge the battery as well as run electrical components reduces the effectiveness and life span of the alternator.

Vehicles residing in an extreme climate, such as the Northeast during winter or the Southwest in the summer, have extra demands from the weather on the electrical system. In these cases, using the alternator as a battery charger does not allow the battery to become fully charged, because the alternator cannot keep up with the electrical demands along with charging the battery.

When the alternator is replaced, always take the time to properly charge the battery with a charger. Taking an hour or two will save time and money by not having to replace the alternator you just put in, or the battery you were trying to save in the first place!

Copyright © Smitty’s Auto Service, Inc. 9/30/10

These repair tips are provided by Smitty’s Auto Service, however we accept no responsibility for repairs you make via these tech tips as they may not be appropriate for your vehicle, so use them at your own risk. Please seek advice from a professional mechanic for all repair problems or contact Smitty’s Auto Service for more information:
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