How can i tell what kind of alternator is in my car so i can replace it

Not without testing , hooking up a scan tool an checking for stored DTC'S - diagnostic trouble code's . The battery lasting only a day or so is because the alternator isn't charging it . That's what the battery light on is telling your.
You don't say what make , model an year vehicle it is ? Your best bet , take it to a qualified repair shop. Most vehicles the alternator is controlled by the PCM/ECM - engine computer . Just replacing parts isn't going to fix it .

Nicole; check the alternator belt, loose,worn, is it still there and on.
If battery is new and connections are good, and belt is good, probably a bad alternator. Alternator cost $125 to $200, labor $60-$120
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I DOUBT THAT IT WOULD BE CONNECTED TO THE ALTERNATOR, BUT MAYBE FROM THE REGULATOR.

first,what kind of car? second,how do you know the alternator is working?let me tell you how the alternator and the battery light works. the bulb receives ground from the alternator when the alternator either isnt spinning or if the alternator is defective,so when the alternator is spinning and said alternator is in working condition, the alternator sends power to the bulb,and with no ground,the light goes out, so,to answer your question, install a reman or new alternator because your is bad.

Could be a bad battery or a bad alternator, or both.

A bad battery can hinder the performance of an alternator and a faulty alternator can slowly kill a battery.

Check your battery fluid levels and acidity concentration. Do not replenish fluid level with plain tap water as it will finally spell doom on the battery.

If you can still drive the car, take it to your nearest auto parts dealer. They usually have basic maintenance checkups for free. One of them is testing the charging system and they will tell you right up if the problem lies in the battery or the charging system.

A bad battery is a blind alley. If it's bad then replace it.

If you still want to hack at it at home, and all is OK with the battery, there is an old way of telling whether the alternator is working properly. But it's kind of dangerous if you do it wrong.

With the engine running, place the flat part of a flat head screwdriver on the side of the alternator, opposite to the v-belt or serpentine pulley. I'm talking about the center of the back cover of the alternator. Make sure you do not touch any electrical connections with the screwdriver as you may cause a short-circuit and experience fireworks. The tip of the screwdriver should be safely away from any spinning pulleys and belts.

If you feel a magnetic 'pull' on the screwdriver from the alternator body at the center of the back cover, it is a good sign that it is actually doing its job, charging that is. But only that.

An alternator "alternates" between powering all things electrical in your car and charging the battery. There is a small, replaceable thing called a "voltage regulator" that when it goes bad, it kinda gives you battery problems. You can buy one and replace it yourself or you can have someone do the dirty stuff.

In any case, a good, professional, clean, and thorough checkup is always the best option.

Hope it helps.

Well the alternator is driven by a belt. You should be able to look at the alternator and tell if it has been replaced by how clean it is.

Well the battery light is telling the driver the alternator is not charging the battery.
So the battery and alternator would need to be tested.
The noise could be the alternator ?

You should have a separate one a/c on that car. Then you have a longer one to drive the other accessories.

Your alternator is likely to blame if anything electrical slows or lights dim while you are driving.
If your battery frequently discharges, your alternator likely needs to be replaced.
If your alternator light comes on or flickers when you start your car, you should have your vehicle inspected as soon as you can.
If your vehicle does not start, your alternator could be to blame. The problem could also be your battery, so check its charge.
A clanging or rattling sound might be an indicator of something gone wrong with the alternator belt or its other parts.


Before paying money for a new alternator (which I was about to do today), be sure to have the alternator tested. As many people suggest, Auto Zone, and other parts suppliers, will test it for free. You may have bad connections into your alternator...make sure they are secure and free of corrosion. You might also simply need to tighten the alternator belt. A loose belt will also prevent the alternator from charging the battery.

Your best bet would be to pick up a Chilton manual from autozone. It will give you step by step instructions on how to do all kinds of things with your vehicle, including the motor mounts.