Q: Q: Battery or alternator

asked by on

Hello how would I know if my battery is bad or if my alternator is gone...had to get charge ran for a couple of days. Will not keep charge

My car has 177000 miles.
My car has an automatic transmission.

This may be a sign of a weak battery, a failing voltage regulator or failing alternator. As you may know, the alternator is responsible for charging the battery while the engine runs by generating amperage and recharging the battery while the engine turns the alternator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. Often times this will result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. 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. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, 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
  1. Home
  2. Questions
  3. Q: Battery or alternator

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: Flood Damaged Honda Accord. HELP.

Flood damage is a serious problem. When most people hear flood, they turn and run for the hills and there is a reason for it. First, even if you didn't fry all your electronics, you are asking for rust and...

Q: Wont start after timing belt replacement

If you are getting fuel and compression, then you need to check to see if you have spark. If you do not have spark then test the ignition system or crankshaft sensor using a scan tool. If your engine was...

Q: Plug from camshaft position sensor corroded.

Even though you can get the car to start and run by sticking the wires into the connector, it will not keep out moisture and it could corrode even more. I would recommend having a mechanic inspect the sensor and...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...