Car Battery or Alternator: How to Tell Where the Problem Lies

January 27, 2012

Almost all of us have experienced the problem where either your car battery or alternator just conks out, and you can't make out which one to replace. Its not easy finding out exactly which part of your car is giving you the trouble, but here are a few tips by which you can find out whether you have car battery problems or alternator problems.

Check Your Battery First

Start by checking your battery first. In cold weather, it's very common to have a dead battery that just won't start. Check the battery gauge on the dashboard to make out if the battery is sending a charge even when you have switched off the car. If there is a dim flickering light, then it means that something is using up power from the battery. You can then proceed to check the connections you commonly use, like the automatic window openers, windshield wipers and the brake lights. Switch them all off and try the battery again. Clean off any corrosion and check to see whether the battery will charge up again. Then check the battery voltage with a voltmeter. It should read close to 12.6 volts when the car is off. Then turn on the engine again and check the battery. If the voltmeter reads between 14-15 volts then the battery is normal. But if the battery reads over 15 volts or less than 13 volts, then there might be a problem with the voltage regulator, the wiring or the alternator. If the battery just wont keep a charge even when you have turned off all accessories, then it's time to take a look at the other systems that work with the battery to run your car.

Check the Alternator

Test the alternator to make sure that it can start up the battery. If the battery is working properly and nothing is wrong with it, then it's the alternator that will more likely cause a problem. A simple test to check the working of the alternator is by running your car; and then unplugging the positive connection of the battery. If the car stops, then you most likely have a problem with the alternator. Another simple test is to check your interior lights. An alternator charges your battery when the car is running. If the interior and dashboard lights come on brightly but slowly start to fade, then it indicates a problem whit the alternator. It demonstrates that the alternator cannot keep a charge when the car is running. Another sign is that the car lights run brightly when you race your car, but when you slow it down, the lights start to lose power.

We also recommend that if you have a dead battery, get a jump start done and check the battery and alternator at the garage. Most garages will do this absolutely for free and it just takes about five minutes.

Related Questions and Answers

How Much is an Alternator for a Car?

If you find yourself wondering, how much is an alternator for a car, here is a quick rundown of the costs. Replacing an alternator can be fairly expensive. The total cost will depend on the vehicle you are driving, as well as if you choose a brand new, or a rebuilt alternator. If you can do the work yourself, a rebuilt alternator can cost as little as $80 for older vehicles. An alternator for a newer vehicle can run $150 to $200. If you need a professional to install your new alternator, budget between $300 and $500, depending on your car. High end sports and luxury cars will cost even more.What are the Main Components of an Alternator?

The alternator helps maintain the voltage of the car battery. There are four main components of an alternator. The stator and rotor are belt-driven magnets encased in copper wiring. They create a magnetic field. The belt is driven by a pulley that connects to the engine. This spins the rotor and creates a magnetic field. The stator uses this to create voltage and electricity which flows to the diode. The diode assembly than converts the AC electricity to DC, which is used by the car battery. Finally, the voltage regulator acts as a surge protector for the alternator.Where Can I Find Second Hand Alternators for Sale?

Second hand alternators are pretty easy to find. Visit a local junkyard or parts recycler and they should have a wide selection of alternators. Another good source is the want ads of your local newspaper. Car parts are normally listed in the automotive section of the want ads. Craigslist is another good source of car parts. People parting out vehicles often sell the parts online and if you know what you're looking for, bargains can be found. Auto parts stores often sell second hand or rebuilt car parts, including alternators. Doing a web search for used alternators will bring up a number of sites. It's a good idea to check reviews of any sites before ordering, because there can be some shifty operators out there.What Do I Use for Checking a Car's Alternator Output?

Checking a car alternator output is fairly simple, if you have the correct tools. A digital voltmeter is required. These can be purchased at an auto parts store. They usually cost between $25 and $40. This procedure is easier if you have two people. One will hook up the voltmeter and the other will start the car at the right time. A voltmeter hooks up to the car's battery, just like jumper cables. Once the car is started and is being revved, you should see an output reading on the voltmeter between 13.5 and 14.4 volts. If the reading is significantly above or below this number, you should have have the car checked out by a professional.

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