Charging my voltage meter is reading 14-15 volts almost into the red for overcharging, this just started happening could it be a battery thats going bad? or the alternator?

a few tests to see if alternator has gone are. start the car and the red light should go off on the dash. start the car and take a lead off the battery ( the car should still run ) and start the car in the dark.turn head lights on then hit the gas,the lights should go brighter as you rev...hope this helps

well are you sure that you have a good or it just shows the correct amount of voltage. which that should 12.6 volts for a fully charged battery. to actually answer your question, (assuming)
you do have a good battery your alt. shouldn't keep it from cranking unless it is locked up, but you would use a digital volt meter and select the d.c. volts setting touch the red (positive lead) to the red (positive post) on the battery and the ground ( black lead ) to the ground terminal on the battery (negative post). it should read very close to 14 volts. if not check to see if you are getting voltage to your alt. by using your volt meter to test the power wire going to your alt. it will be the one on the backside of your alt with a protective boot over it. with your volt meter still set on dc volts touch your black lead lead to a good ground and your red lead to your power wire going to your alt. it should have 12 volts there. if not check your fuses. if your car clicks when you try to start it then you may have a bad battery connection. dirty terminals with corrosion built up on them will do the same thing. also a starter that is bad will click because the bendix can't kick out to engage the flywheel to turn your engine over. well hope i answered your question and then some.

if the battery light is on while running the charging system is not working.you can check
with a volt meter,setting meter to dc volts & connect meter leads to battery.reading should
be 13.2 - 14.5 volts if lower than this your only reading battery voltage.check single red wire to the alternator it should read battery volts 12v.if battery voltage is present than alternator is faulty,if no voltage reading you'll need to trace & repair the wiring
note; battery should be fully charge before testing

good luck

Sounds like you may have a bad alternator. Put a volt meter across the battery posts. A fully charged battery should read 12.6 volts. Then start the engine and the voltage should increase to 13.5 to 15 volts. If you do not get this increase in voltage, then the alternator is not charging, which can be either the wiring to the alternator or the alternator itself being bad. Good luck :O)

Do you mean it will not hold a charge the battery You may have a short Do you a meter to check voltage if so dicsconect negtive cable from battery set meter to 20 volts dc take red lead from meter to B+ on battery positive side then take black lead from meter touch to engine ground engine block or anything like that if you read any voltage at all you have a short a positivetly charged wire touching ground If its a low reading like 1 volt or under its something small like a small light or a switch of some kind BUT if higher voltages you need to look at systems that draw more voltage like motors seats windows starting motor ECT.YOU CAN ALSO START UNPLUGING FUSES ONE AT A TIME IF THE VOLTAGE GOES AWAY ON THE METER YOU WILL KNOW THE PROBLEM IS SOMEWARE ON THAT CURICUT good luck

Have a volt meter? If so start the engine if you can get it charged uo and set the volt meter to 200
Them make sure the volt meter is set to the AC mode. I know it supposed to be set to the DC mode although we are doing a test, correct? Now with the meter set to the DC mode and the engine running, take the positive probe which is the RED one and place that on the NEGATIVE post of the battery. Now put the BLACK Probe one the POSITIVE side of the battery. If a reading of voltage shows of any sort the diode in the altenator is at fault. That problem causes the system not to charge the battery. Generally a diode will got out upon jumping another vehicle. You stated you bought an altenator new. If so new ones cost hundreds of dollars. If a lot lees you had purchased a rebuilt. Rebuilder do screw up so you may have a bad on here so running this test may find your problem very easy. If the voltage reading reads OL the altenator diode is good.

check with a volt meter if u have 12 volt at the big lead on the back of the alternator engine off

if thats good start engine check to see if alternator is charging check the battery a good alterntor charges 13.5 - 14 volts, u may have a bunk alternator

With volt meter on battery start car and read voltage. When yo first put the meter on a full charged battery it should read between 13-15 volts. When you first start motor the voltage should go 3-4volts higher then when you first put it on. And then tapper down after awhile. If there is no voltage increase after start alternator is out.

They have expensive tools and equipment to test alternators but you can get by with a simple digital volt meter. With the volt meter on DC voltage attach each lead to the corresponding terminals on the battery. With the engine running and all the electrical loads on (such as the head lights, radio, defrost, wipers, radio etc). the voltage reading should be between 13 and 14 volts. If you actually only have 9 volts then the alternator isn't charging and you'll have to look in to that more. The truck wouldn't be able to start or run very well with only 9 volts so i'd be willing to bet the gauge is bad or possibly a wiring fault.

use a volt meter while the car is running to check the main wire or large red wire coming off the back of the alternator it should read a steady 14 volts, the volt meter must be set at dc 10 amp settings, ground the black wire to ground or a metal surface some where on the car and touch the red probe wire on the volt meter to the main terminal of the alternator as i said it should read a constant 14 volts if it doesn't the alternator is bad.