whats are some signs of a bad Alternator?

Answer 1

Best and easiest thing to do is to check the voltage at the battery with the motor running. If you need to charge the battery to start it, then make sure the cnarger is disconnected first.
The voltage with a working alternator should read OVER 13.1 volts with no heavy loads (like defroster etc) If, after a few minutes with the engine runnung, you notice the voltage drop or if the voltage is under 12.5 volts, then the alternator should be checked or replaced. This happened to me with my '98 Grand Prix., I suspected the alternator, and when I did the above test, the voltage was 11.7 and falling slowly.
New alternator and it was 13.8 volts.

Answer 2

Signs Of A Bad Alternator

Answer 3

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The electrical system in an automobile is said to be a 12 volt system, but this is slightly misleading. The charging system in most cars will generally produce a voltage between 13.5 and 14.4 volts while the engine is running. It has to generate more voltage than the battery's rated voltage to overcome the internal resistance of the battery. This may seem strange, but the current needed to recharge the battery would not flow at all if the charging system's output voltage was the same as the battery voltage. A greater difference of potential (voltage) between the battery's voltage and the alternator's output voltage will provide a faster charging rate. As long as the engine is running, all of the power for the accessories is delivered by the alternator. The battery is actually a load on the charging system. The only time that the battery would supply power with the engine running is when the current capacity of the alternator is exceeded or when engine is at a very low idle Some people tell you that you can check your alternator by disconnecting it from the battery to see if the alternator can produce enough current to keep the engine running. Disconnecting the battery will subject the voltage regulator (and computer and audio equipment...) to significant voltage spikes which may cause an otherwise good alternator to fail. Even if there were no damaging spikes, this test would not indicate whether or not the alternator was good because the engine will easily run with a weak or failing alternator. If you want to see if your alternator is producing current, turn on your headlights when you're parked and the engine idling with the headlights shining on a wall (at night). Notice how bright they are. Then turn the engine off. The lights should get dimmer when you turn the engine off. If the lights get brighter when you kill the engine, the alternator was not charging sufficiently. When doing this test, the lights should be the only load (turn the stereo, a/c and other accessories off). With a heavy load, an otherwise good alternator may not be able to produce sufficient amounts of current at idle.

Answer 4

Alternator Problems

Answer 5

Well, the obvious sign is the your car dies and doesn't start. But common signs of alternator failure are: dimming lights, the heater doesn't function, the radio dies, and the battery light is on the dashboard. The other good indicator of alternator failure is if you start your car and do not hear a whistling sound coming from the alternator. This means it is not charging and is done for. Of course before assuming the alternator is bad, it would be a good idea to check the belt and the battery cables, severe corrosion of the cables could cause the battery not to charge as well as loose cables.

Answer 6

At this time of year the first sign you notice may well be the starter sounding slow first thing in the morning because the alternater is not able to fully charge the battery. If the the alternater has no output then you should see a red warning light on the dash when the engine is running. Any garage should be willing to test both the battery and alternator for a very small cost and many will do it for free.

Answer 7

Generally the signs of a bad alternator is that you are losing the charge in the battery rapidly. You could have a brand new battery, but if the alternator isn't replacing that charge, then you're running straight off the battery, and that won't last for too long.

If you're just having electrical problems in your car, depending on what year car you have, check the fuses ( first thing ), then the alternator, distributor, and ignition coil. But for battery drain, it's usually the alternator, without question.

You can either replace it with a new one, or sometimes you can save a few bucks and replace it with a rebuilt one.

Answer 8

It's simple. If your battery is good and yet it doesn't seem to be holding it's charge then you have an alternator problem. The alternator is what keeps the battery charged and if it's not doing it's job then you will need to change it. But, check the battery first as it's a lot cheaper to get a new battery than an alternator!

Answer 9

DO NOT disconnect the cables while the engine is running - depending on the year of your car doing so could zap your computer. First of all your battery needs to be fully charged and tested. Then have the alternator checked for voltage and amperage output under a load. Many of the DIY parts stores will do this for free. It is common for one to kill the other, that is to say, if your alternator is going bad and you wait until it becomes a drive-ability problem, then the battery will have suffered stress to the point of breaking. (cease to function properly) Same is true if battery is failing. Make sure if you have one replaced, the other is at least checked, as a vicious and potentially expensive cycle could occur.

Answer 10

When the battery light keeps coming on, or when a recently fully charged battery or brand new battery constantly needs to be jumped, or the most annoying of all is when your whole car just shuts down while you are driving and even the warning lights won't work. These can also be signs of a bad starter, as well.

Answer 11

Please don't do the test that many are suggesting on here (pulling a battery cable with the car running) unless you have a very old car. As your car is running, some of the current from your alternator is flowing back to the battery to keep it charged..when u disconnect your battery cable that extra current goes to other parts of your electrical system and can quickly fry your voltage regulator or entire computer. Before computers were put in cars, this test was fine...in todays vehicles u could find yourself with a very expensive problem in less than 30sec.