Q: Battery or Charging system problem

asked by on November 27, 2016

My car died in my driveway yesterday, I went out and checked my fuses and the connections on my battery. The voltage read 8.4. Today I jumpstarted my car and it started right up, the voltage went up to 15.1. Within 15 minutes the car was dead again with 8.2 volts last time I checked. A few minutes ago I went out and checked what kind of battery I have. When I unlocked my car what little power I still have came on. When I opened my hood I could hear the battery making what sounded like a boiling sound. Could my problem be just a bad battery or something with my charging system like the alternator overcharging?

My car has 40701 miles.
My car has an automatic transmission.

This may suggest a failing voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

Was this answer helpful?
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

How do I detach the rear seat belt comfort guide?

The rear seat belt comfort guide is easy to detach. All you need to do is pinch the seat belt, and slide it out of the guide. Then return the guide to the storage compartment on the side of the...

How do I replace the air bags?

Any time an air bag is deployed, it will need to be replaced. You should not drive your vehicle until the air bags have been replaced. Only a qualified mechanic or dealership should replace the air bags in your vehicle....

Valve cover gasket 2012 Ford F-150

Hi - Here at YourMechanic, click here for guidance on how to make this repair. There are many other aftermarket sources for information on how to replace valve cover gaskets: the factory Ford Service Manuals, vendors of aftermarket service manuals...

Related articles

2012 Toyota Prius vs. 2012 Chevrolet Volt: Which One Should I Buy?
While these two vehicles are both certainly cost-effective to drive, they can be difficult to compare due to the Prius’ entry in the mid-size category and the Volt living squarely in the compact car category. Both of these vehicles are...
A Buyer’s Guide to the 2012 Ford F-150
The The best-selling pickup truck in the US for over 30 years, the Ford F-150 has a lot to offer in reliability, durability, and the features that buyers want in a truck. The 2012 F-150 is not only a tough...
A Buyer’s Guide to the 2012 Chevrolet Avalanche
Few Few vehicles are as distinctive as the Chevrolet Avalanche. Part SUV, part truck, the Avalanche is actually surprisingly practical. On the inside, it feels more like a Chevy Tahoe, except when you look out your rearview mirror, you’ll notice...