so i have 2 questions. my battery is getting charged sometimes all the way to 18v. 1. what bad stuff might happen if i just let it do it and not fix the problem. (cant figure out what the problem is) i have replaced the alt. and the battery and my battery cable ends. it wont start charging it like this till about 20 mins into any trip if the car is cooled off to begin with. the latest news is that i disconnected my neg battery cable while it was running to see if it was the alt. and it didnt die, but it did start to run bad and the windshield wipers went crazy. 2. any ideas? thanks guys.

 

Woah!

18v is BAD.

You've confirmed this with a voltmeter at the battery terminals, correct (not just relying on the dash gauge)?

If it is doing this, you need to stop driving it. That kind of voltage will rapidly fry expensive things (like the ECU, CPU, and other jazz).

Take your alternator and battery in to a shop, get them tested. If it only happens when the car is warm, take the alternator in hot. It's not unheard of for a new alternator (reman) to be bad.

-=Russ=-

 

yeah thats with a voltmeter. and i have an alternator coming tomorrow its under lifetime warranty. it is the 2nd i have gone through. so i figured it should be fixed or something else is frying the alt when i put a new one in.

 

Are you sure you are reconnecting the 2 wires that go to the back of the alternator? They provide bias to the voltage reglator. Might also be a good idea to check those wires with a continuity tester (they end under the dash...grab your trusty copy of the factory service manual and look around the ECU area).

 

ok first im going to state i have an s5 and im not sure what 2 wires you are talking about. if i remember correctly the voltage regulator for the s5 is in the alternator.

 

ok so i just tested my alternator how the factory service manual says and it is a bad alternator. so i guess my next question is what could be killing my alternators or is it that i just keep getting bad remans from autozone?

 

There is a two wire connector that plugs into the alternator, as well as the large wire that goes to the fuse box. If the 2 wire connector is not plugged in, you will see these exact symptoms.