Alternator Failure or Dead Battery-Who is the Real Culprit


Nothing is more frustrating than trying to start up your car only to realize its not working. We have been there at one time or another, but sometimes it just not clear as to what, if anything we need to replace. Batteries and alternators work closely together and sometimes it may be hard to tell which one needs fixing. Before running out to buy a new battery or alternator, take a moment to search for the real issue at hand. Don’t panic just yet! If you’re lucky it just might be a quick fix!

First, we recommend giving your engine a quick check by first inspecting your battery and its wire connections. It’s free and sometimes it just might be the problem. Months ago, my daughter told me she went out to eat only to come back to her car and realize it was dead. She heard no clicks, or even a whisper from the starter, silence. In a panic, she called a tow truck driver, instead of me. $75 (minimum charge) later, the driver quickly pointed out that one of her battery wires was loose and needed to be tightened up. A few minutes later and for her, $75 less, they were both on their way. An expensive lesson she will never soon forget! If the connections are secure, check the condition of the battery wires themselves to make sure they are in good shape and not frayed or splitting. Clean cable ends of any corrosion and replace if needed.

If that’s not it, you are probably phoning a friend, calling for roadside assistance or if you’re a do-it-yourselfer, problem-solving using some of the following methods. Check your battery’s voltage with a voltmeter or multi-meter. Voltmeters or multi-meters can be found for about $20 bucks at a store near you that sells auto parts and is an invaluable tool to have around and help you problem-solve issues like these. With your vehicle’s engine off, match negative with negative and positive for positive and you should be hoping for about 12.6 volts. If it is below 12.4, you may need to have the battery checked. Many local auto stores test your battery for free and can help you make this final diagnosis.

Now turn your engine on and your meter should now read 13.0 to 14.8 volts depending on your engines RPM and your type of regulator set-up. You are doing this to see if the alternator is properly charging the battery by sending it the proper electricity. Any higher or lower voltage than this range, points to possible alternator issues of which we’ll also address below. There is another way to tell which part may be the cause and that’s by disconnecting the battery’s ground cable, but we don’t recommend that. Not only can it not be accurate in some circumstances, but this method may cause damage to your car’s electrical system.

Other methods to check your alternator is by observing your lights. Turn on your headlights and while in park, have someone look at your headlights while you press the accelerator. If the lights remain the same even if you take your foot off of the gas, your alternator should be fine; if the lights dim or flicker; your alternator may be at fault.

Please keep in mind that this article serves as a general guideline. There are numerous makes and models of vehicles and what applies or works for one may not be the case for the other. While many of these tests can be done at home, we always recommend having these tests and any repairs and/or installations done by a professional. Safety is always our number one concern as is saving our customers money in the process! You can always find the best deals on starter motors and alternators with free shipping and no core charge at Our online store is always open 24/7 to take your order or take advantage of our live chat or great customer service during regular business hours at 888-970-4622.