My battery is drained after my car was park for 3-5 days. I bought a new battery thinking the old one is bad but it was drained again after I park it for 4 days. I know this is not an alternator problem. The lights were off and even the alarm. I have no sound sytem in my car although the previous owner had it installed. I took it off to save weight. Something is draining my battery.

 

check the little lights, like the ash tray and glove box. then, check your wire connections left in the dash from the stereo you pulled out and make sure there isn't one that's touching something and draining power. Also, do you have any other electrical components? EBC's, TTs, etc.

 

And Yes... It very well CAN be an alternator problem. Most alternators fail because the internal voltage regulator goes bad. This is not your issue though. If the alternator has a bad DIODE it will do EXACTLY what your car is doing right now. I know this from experience. By the way mine suffered DIODE failure when it was about 1 month old. It can happen to the best of them. Cheap alternators are more likely to suffer though.

Rod.

 

I don't think it's the alternator because the battery is being charged when it's running. The battery is only drained when I don't drive the car for 3-4 days. When I was driving it almost everyday the battery never died. Something is grounded a open wire maybe. With the Z it's gonna be a pain in the a$$ to find that wire.

 

did you test it with a volt meter? that will save you a lot of head aches.

 

I wouldn't count out the alternator right away. My 240z has an external voltage regulator and it went bad and caused the same symptoms you're talking about. Your alternator is internally regulated, so the regulator inside the alternator may be bad. But check the easier stuff first.

 

I have the EXACT same problem, I drive my car for a week, and leave it sitting for like 3-5 days, and it will be dead. I am about 90% sure it is the alternator, It still keeps the car running and can charge the battery for the next time I want to go use it, but it doesn't produce enough to allow the battery to sit for longer than a couple of days....I'm too lazy and poor to swap it out, besides it isn't really on the top of the list just yet.

 

How hard is it to change the alternator on the 300zx. Will I be able to change it without using a lift just a jack stand. Any tech article on it. Help please!!!

 

The easiest way, to me, would be to jack up the car and set on jackstands, remove the lower front plastic shield under the car, then drain and remove the radiator. That way you'll have plenty of room to get to the belts and bolts.

 

all i did to change mine was lift up the car and loosen the sway bar. Came right out.

 

does any one know if a higher output alternator that gives more then 90 amps?? that is bolt on and doesnt require and special mods?