Skip the auto shop - Our mechanics make house calls

Q: Alternator, Serpentine belt, or battery?

asked by on

So, my car had died about a month ago after having about a week or so of really soft starts. I got it jumped, I unhooked the positive from the battery and it ended up staying on. The internet told me this means it's not the alternator. So I buy a new battery from Autozone and the car starts working normally again.

Now 2 days ago, so a month from my purchase of the last battery, I was driving home and the engine shut off while at a stop light. It wouldn't turn back, it wouldn't even crank. I got it into neutral and pushed it to the side and got towed home.

We tested a few things, if it would turn at all (it didn't) and if anything in the car worked (it didn't). Not even the electric windows would roll up.

So (yesterday) we jumped it, left it on for about 30 seconds and it died. We bought a new battery and it started but i unhooked the positive battery cable and it died instantly.

Is it just a bunk battery or alternator issues and could it possible be the serpentine belt?
My car has an automatic transmission.

A: Hi there. It sounds like the alternator has...

Hi there. It sounds like the alternator has failed. What the internet didn’t tell you was that the alternator’s voltage during idle and load as well as its output amperage during both conditions needs to be tested to properly determine the state of health of the alternator. This is not to say that what tests good today will not fail tomorrow, but it means that at that moment it is operating properly. Your alternator may have been losing its charging capabilities when you checked the first time, but was charging enough to keep the engine running. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with an electrical problems inspection.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car chokes when accelerating and when at a stop

Hi Nadia. The check engine light can come on for many different reasons. However, I believe your light is related to the symptom you've described. A catalyst problem wouldn't likely surface as this particular symptom. When you say the vehicle...

Q: Speedometer not working

Hi There, This could be related to a couple of possibilities. The [instrument voltage regulator]((https://www.yourmechanic.com/services/instrument-voltage-regulator-replacement) regulates the voltage supplied to the various gauges in your vehicle’s dash. When this is not working properly, this may cause the gauges in your...

Q: Car not reversing, but going into forward.

Hello, the transmission your car is equipped with has a dedicated band that locks up to one of the drums to make the trans rotate in reverse. This band is only applied in reverse and manual low (putting the shifter...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.