Bad alternator?

[Que-45]

My Dash is reading low battery, recharge. The battery is brand new and fully charged. My abs and brake lights came on in the dash. The alternator belt is new and tight. Are these the warning signs of a bad alternator? I noticed that my windows were rolling up a bit slow today too. Any of you guys expirience the same problems? I just want to make sure the alternator is what needs to be replaced before I buy it.

[elwesso]

I would take the car to autozone, they can do a very rudimentary test to see if your alternator is bad, and it doesnt cost any money.

[blacklist74]

Take the positive cable off the battery while the car is running. If if shuts off, it's your alternator. If the problem continues after the cable test, take it out and have it checked by AutoZone (free). Have fun taking it out and putting it back...It's a real pain....

[qsiguy]

Take the positive cable off the battery while the car is running. If if shuts off, it's your alternator....

While we used to do this on older cars I wouldn't recommend it on newer highly electronic cars like the Q. The test will work but you can damage stuff. Your battery is helps to protect your system from spikes in voltage from the alternator, even if it's bad. Take it to Autozone or Checker and do the free test first.

Low or high output on the alternator can do weird things. ABS, brake, SLIP, and TCS OFF lights can all come on in the event of battery/alternator issues. Last time my alternator failed the voltage went UP and I got ABS, SLIP, TCS OFF light all coming ON and my windows actually went super fast! My system was getting 17-19 volts.

[Skibane]

Take the positive cable off the battery while the car is running.

That was good advice, back in 1950...

On modern vehicles, it's a great way to turn one electrical problem into several dozen or so -

The battery serves as a voltage stabilizer and filter. When you disconnect it, your voltage regulator doesn't have a stable voltage to measure - instead, it sees whatever voltage the alternator happens to be producing at that particular instant. Instead of reacting to a voltage that gradually changes over several minutes, it suddenly has to react to voltages that are changing almost instantaneously. Result: Huge voltage spikes and sags.

Worse yet, since your alternator produces pulsating DC, its output swings from zero to 20+ volts anywhere from several hundred to several tens of thousands of times a second. Without a battery in the circuit to smooth out these pulsations, every electronic device in your vehicle receives this "raw" DC power.

With literally hundreds of electronic circuits in the average modern car, you're just begging for trouble by exposing them to this garbage.