Low Charging Voltage
Thread Starter
Instructor
Joined: Sep 2002
Posts: 198
Likes: 0
From: VA BEACH VA
Low Charging Voltage
Hey guys, I have a problem with my 87 Vert and need some opinions as to the problem. In normal operation and at any speed my voltmeter normally reads between 13.5 and 13.7 and I never have any problems. However, I have noticed that if my heat or A/C is on the voltmeter will not show higher than 11.5 or 11.6. I put my meter on the battery and the voltage is the same. My heat and A/C both work fine and the blower motor seem to work fine at all settings. I need to know if I could have a blower motor going bad or do I have something else restricting my charging system? If I don't turn my heat or A/c off it will drain my battery in short time.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You likely have a defective alternator because it cannot supply normal a/c & blower motor current. HIGHLY unlikely, if the a/c & blower motor draw more than 105 amps (I doubt that very very much, you'd have fire and smoke), then the alternator voltage regulator limits the output current by dropping the alternator voltage. Starting with a cold engine, you should see 14.3 volts on the dash voltmeter and this will drop to 13.3 volts when the alternator gets to its operating temperature. If you have 13.3 volts cold and no a/c & blower motor on, then I would suspect a defective alternator. You can take your alternator to a parts house for a test and they should be able to determine if it is ok or not.
Your voltage regulator may be defective and if you are game, you can replace it yourself. It is inside the alternator and not very hard to replace.
Your voltage regulator may be defective and if you are game, you can replace it yourself. It is inside the alternator and not very hard to replace.
Last edited by jfb; May 13, 2010 at 12:48 AM.
