Q: Weak battery or alternator?

asked by on November 18, 2016

I think my alternator's going out. When I turn the key to start it, it sounds like the battery's dead. Like, it starts but it takes a second. Also, my windows are suddenly rolling down very slowly.

My car has 277397 miles.
My car has an automatic transmission.

Battery will not hold a charge Inspection $79.99 - $89.99 Get a Quote

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.

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

What others are asking

Engine went into "limp home mode with power train fault wrench indicated in dash. It will not accelerate. Not pulling any load.

Hi there. Your vehicle's wrench light, Check Engine Light and lack of performance go hand in hand. The vehicle's PCM (powertrain control module) has recognized a fault and put the vehicle into limp home mode. It could be, a throttle...

Power steering fluid shoots out of cap when turned off and wheel is not turned?

You may have an air leak at the pump and thus air is being continually drawn in, and building enough residual pressure that must be relieved once you shut the p/s off. The pressure is too much to bleed of...

Code AWD malfunction came on, car is in AWD permanently. Transmission working fine.

Hello there, many faults will cause your 2005 AWD malfunction light to be on in your 2005 Ford 500. The most common faults are the shift linkage, low fluid level, or a wiring harness fault. A qualified technician, such as...

Car shuts off at idle

Hi, thanks for writing in. This is a sign of a failing idle air control valve. This is a unit that regulates the air flow into the engine as it is mixed with fuel prior to being injected into the...

How do you operate the Turn Signals?

Your Turn Signals provide important directional information for drivers behind you as well as those approaching you. They tell other drivers that you’re about to turn, so they can expect to slow down and will begin backing off (it also...

get a clunk wheb i accel from complete stop.

You may have problems in the driveline or rear end or transmission and should have the problem checked by a mechanic like one from YourMechanic before problem gets worse.

Car hesitates and jerks uphill

It's possible that your vehicle may need a tune up. If your vehicle is equipped with a distributor, the cap and rotor should be replaced as well. I would recommend help from a certified mechanic to assist you with your...

How do you disable the auto lock mechanism on a Ford Explorer 'LIMITED'?

Hi there. The following steps are how to disable the auto lock feature in your vehicle. Confirm that the vehicle alarm is disarmed. Close all the doors. Make sure that the ignition switch is in the 'OFF' position. Turn...

Oil leak and shaking

The oil filter, filter housing, and the oil pressure switch is on the left or drivers side of the motor. The shaking can be from a problem with the camshaft's tensioner and guides. If the oil leak is on the...

Related articles

2011 Dodge Ram vs. 2011 Ford F-150: Which One Should I Buy?
Large trucks can be fun to drive, and even more fun to get dirty. Unfortunately, they may also cause you to get phone calls from friends who need to move into a new apartment. Fortunately, just having a truck may...
The Top 5 Selling Cars in Kansas in 2012
Kansas Kansas sees a varied climate with all four seasons, which means drivers in the area choose a variety of vehicles. In years past, some of the front-runners have included the Ford F-150, Buick and Toyota Camry. 2012’s top five...
The Best Used Cars to Buy If You Live in a City
Living Living and driving in the city means you’re faced with parking constraints, narrow streets, and the constant stop and go of traffic. With all of that said when you’re ready to purchase a used vehicle these are all things...