Previous dead battery

KBVSFLW

MEMBER
1998 MERCURY MYSTIQUE
95,000 MILES

Gents: this is my sons car, and we previously jumped it, thinking the battery was dead or dying, or that there may have even been a dome light left on, etc.

Then, a new battery was purchased and installed by Walmart auto center.

Now, doesn't start again, and had to be towed to a shop.

What are the possible problems?
What are the things we should ask/tell that shop to convey we know what we're talking about?
What are the typical alternator and/or starter repair costs we should expect?

Kevin

1 Reply

CARADIODOC

MECHANIC
33,741 POSTS

It's almost certain the generator is not working. You can easily verify that by using an inexpensive digital voltmeter to measure the battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it is low you can do a simple test to determine if the voltage regulator is the problem. A failed regulator and worn brushes are the two most common causes of a no-charge condition. The regulator is easy to replace and it comes with new brushes. Depending on which engine you have it can often be replaced without even removing the generator from the engine.