Man, I keep having to boost my battery once every week. This is my three battery in 6 months. So, can my alternator be working enough to run the car, but no charge the battery. I took off the negative cable from the battery while the car is running and the car stays on.. Any ideas.. I checked the voltage at the battery terminal while the @ 2000rpm = 13.3 volts..

 

13.3 is just the slightest below 13.5 wich is good but i would try a currentoutput test, this is where you measure yourmaximum current outputof the alternatorat a specific voltage you might want to take it to battery place unless you have a volts-ampre tester.

 

perform a parasitic drain test, it's simple. Take a multimeter, turn it to the ammeter setting making sure to have it on the highest setting, usually 10 amps, and probe between the negative battery post and the negative cable clamp (disconnect the clamp). Do this with the car off and doors, glove box, trunk all closed and radio off. The reading should not be higher than .035A, if it is, then something is draining current, like a trunk light bulb who's switch is faulty so it always remains on.

 

I had to jump start this morning again...
I didn't start my car over the weekend. So it didn't run for 2 days.
I am really to change the alternator but I am not sure it is the problem.
I got another test this morning after starting the car. At idle @13.8 volts..
and .25 amps drawn with the car off.. I pulled of the negative cable while
the car was on, and the car kept running, so i am curious..
any ideas again, please..

 

The car will still run without the battery, for a short period of time. That's how we change them at the shop so we don't have to reset all the radio, clock, and other settings.

 

What car is it? I know on my lude, the voltage is regulated to a steady 14.4 volts with the car running. I don't know if that is a standard number for hondas or not. If you are going to take off the alternator, I can tell you some tests you can do.

 

13.3 volts is too low- you probably have a bad regulator- get a HONDA alternator. Voltage should be 14.3-14.6 volts at 2000 rpm.

 

Well first off, 13.x is too low. It should be at 14.x minimum.

Second, don't ever remove the battery terminals while the car is running. Todays cars rely on the battery to filter out spikes that occur normally from the alternator. They can do MAJOR damage to the electrical system if you do so.

I've had your problem, and I'm 90% sure that it's either the diodes or rectifier that has gone bad. Take the alternator out, and have it checked. It doesn't matter that the voltage is 13.x, voltage doesn't charge batteries, amperage does.

Also, check all your grounds, make absolutely sure you have good contact. If you have access to a multimeter, check the resistance between the (-) terminal and different points on the engine block & head. It should be less than 0.1 OHMS.

Good luck!