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Q: Bad alternator needs to be replaced.

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I think my alternator is bad. After charging the battery with a battery charger, it only reads 12.9 volts. The car only goes about 5 MPH at most and then die. Even when I jump the battery it only goes 5 MPH.

A: The alternator is not charging if voltage d...

The alternator is not charging if voltage drops to below about 13.2 volts while the engine is running. If your car will not go over 5 MPH you may have other issues causing this like low fuel pressure or a computer issue causing the problem. The first thing a qualified technican should check is the charging and battery system. Then a computer scan and fuel pressure test if the charging system and battery are ok.

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