View Single Post
  #11  
Old 12-06-2012, 04:35 PM
Tech II Tech II is offline
AF Fanatic
 
Join Date: Jul 2011
Posts: 5,017
Thanks: 70
Thanked 618 Times in 610 Posts
Re: Alternator issues?

I agree, don't disconnect/reconnect a battery while car is running, due to spikes.....

Check voltage when the alternator is hot.....load the the system...turn on lights, wipers, blower on high, and rear defogger....voltage will probably drop to 12 volts, but if you rev engine to 1500 rpms, voltage should increase to at least 13.0 volts......if ok, then I would be looking for a draw....I assume the cables were clean and free of corrosion when you replaced battery?

One more thing...you check/test an alternator with a fully charged battery, not one that is low on charge....alternators are not made to charge low batteries(that's why you get those stickers on new alternators).....alternators are just there to recharge the voltage lost from cranking the vehicle, and then they basically run the electrical in the car when it's running.....when it doesn't do this, then it runs on the battery and discharges it....
Reply With Quote