Correct. On a working system, you should have 12.5 to 12.3 volts within 30 minutes after shutting off the car. When it starts, it should climb to 14.1-14.8 volts if the alternator is working properly. If a battery goes below 11 volts more than a couple of times, the plates start to calcify. Then it goes bad fairly quickly.

 

before start up was around 12.2- 12.5vDC. during start up it didn't dip too much. after start up is stayed around 14.3. I disconnected the positive terminal on the battery. the engine has been running around 15 minutes on the alternators power. it has very slowly been dropping voltage. the lowest it's dropped so far is to 13.8. reving the engine doesn't really make a difference in the voltage like I expected it to.

been running good so far. i'm debating what to do. I can't imagine a bad battery would cause a car to stall... maybe it shorted internally and robbed power from the alternator? is this possible? i'm used to working with AC voltage and things like that happen all the time...

i really don't want to get stranded again. that's a real bummer... do you guys think it would be worth removing the alternator to have it bench tested at an auto parts store? am I already doing the equivalent of a bench test? how difficult is it for someone who's never done this to remove that belt and drop out the alternator?

 

Go to the auto parts store and have them run a "load test" on it. Today's fuel injection systems take up to 40 or more amps of power off the electrical system. If your battery is weak, it can affect the injection system. Especially at idle while the AC is on, Music is blaring, lights on etc.

 

load test on what? the battery? already got a new one and turned in the old for core

 

what's the easiest way to take off the alternator in an 04 g35x?

 

Do you have cel? If so it could be a crankshaft position sensor, common problem on the early year nissans