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Good or bad alternator

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Afternoon guys, my car is acting up again oh..my alternator is what my mechanic is suspecting, I have charged my car battery severally but it keeps going flat. how do I know if an alternator is bad guys?

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Are you really sure u want to test it yourself? its a bit tedious for a lady..

try these.

1. Open your hood/bonnet so you have access to your car battery.  Locate your alternator and check to be sure the alternator belt  isn't loose.

2. Turn your multi-meter to the 20 V setting ,if you don't know what it is pls ask an electrician around for multi-meter.

3. Start the engine.   At this point, check to make sure the alternator pulley / belt is spinning properly without slipping.

4. (The hard part).. there are ways to checking the voltage coming from the alternator. If you can access the alternator without having to get your cloths tangled in the spinning pulley, first place the positive multi-meter probe (red) and touch it to the red terminal connector coming out of the alternator.  Now take the negative (black) multi-meter probe and touch it to some metal part of your car frame (like a bolt head nearby or even the negative terminal on the car battery).  Pls Do not ground to the alternator itself.  That would be potentially bad.  You should now be getting a reading on your multi-meter display. 

 Secondly, If you cant  access to your alternator, then you can simply test the alternator by touching the positive multi-meter probe to the positive terminal on your battery and likewise the negative probe to the negative terminal on your battery.

 

If the alternator is working well, your multi-meter should read somewhere in the vicinity of 14 volts (typically 13.8-14.2).  If it is reading excessively higher than 14 volts (greater than 15 volts) it is possible that the voltage regulator on your alternator is faulty or going bad.  If it is reading lower than 13-14 volts, there are a number of possibilities as to the reason. Just try these first and see... i suggest you try step two.

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WOW!!.. this is too much oh,.. I will try it try it sha. don't just want to believe everything my mechanic says..i always like a second opinion. 

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Normally a car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery.  If the alternator is putting out too much voltage (15+ volts), your car battery will likely spill out its content (ACID) . When a battery is near fully charged the alternator will cease to put out sufficient voltage to charge the battery and the reading you will get from the battery probing method will simply be the voltage coming from the battery itself.  In this case, you can simply leave your lights on with the car off for ten or fifteen minutes to drain your battery a little bit.

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follow what @bazz and @budman  suggestions...also try using a battery tester to be sure your battery is fine..it cud be your battery.

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@bimzy... save yourself the stress and drive down to PARTBOYZ AUTO SERVICE CENTRE.. let them check it for you since you don't want to go by your mechanic..

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