Normal voltage reading with a/c
Thread Starter
Racer
Joined: Mar 2012
Posts: 282
Likes: 1
From: East Windsor New Jersey
Normal voltage reading with a/c
Hi everyone, quick question:
I wanted to test the battery voltage while the a/c is running, stopped at a light. Fluctuated between 11.4 volts and 12.7 volts. Normal idling voltage is 13.5 - 13.9 with no a/c. That was the only electrical thing on, no radio or anything else that would drain. When I turn the a/c off the voltage returns to where it's been. At no time does she even sound like she's going to stall. Idles smoothly. New battery, new alternator, new belts.
Should I be concerned?
I wanted to test the battery voltage while the a/c is running, stopped at a light. Fluctuated between 11.4 volts and 12.7 volts. Normal idling voltage is 13.5 - 13.9 with no a/c. That was the only electrical thing on, no radio or anything else that would drain. When I turn the a/c off the voltage returns to where it's been. At no time does she even sound like she's going to stall. Idles smoothly. New battery, new alternator, new belts.
Should I be concerned?
Drifting
Joined: May 2007
Posts: 1,440
Likes: 19
From: SW Chicago Burbs IL
Pretty normal, the alternator doesn't have as high of an output at idle. You can upgrade to a later model cs144 alternator with a little bit of custom work if you're interested. I did this a few years back and my voltage output at idle is much more stable.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Standard operating voltage is 13.8-14.2 under all conditions! I would put a good quality meter on the battery under the same conditions, and if you still see around 12 volts there is an issue..
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
You have an issue, you should NEVER have under 13V at a very minimum even with full loads.
Is your battery good? Is your power cable from the battery to alterator good? Are the ground cables on the engine block good? (perform voltage drop to test these cables).
Inputs to alternator good?
Is your battery good? Is your power cable from the battery to alterator good? Are the ground cables on the engine block good? (perform voltage drop to test these cables).
Inputs to alternator good?
Thread Starter
Racer
Joined: Mar 2012
Posts: 282
Likes: 1
From: East Windsor New Jersey
Wow, first thank you all very much for your responses. After reading them I've decided it's better to have a look now rather than later. I haven't had any issues so far like odd idling and there's no working radio at present. But the battery is about 3 years old and part of that was spent drained in the winter outside.
Guess we'll see. Anyway, thanks again!
Chuck
Guess we'll see. Anyway, thanks again!
Chuck
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Wow, first thank you all very much for your responses. After reading them I've decided it's better to have a look now rather than later. I haven't had any issues so far like odd idling and there's no working radio at present. But the battery is about 3 years old and part of that was spent drained in the winter outside.
Guess we'll see. Anyway, thanks again!
Chuck
Guess we'll see. Anyway, thanks again!
Chuck
Not keeping batteries charged and allowing them to slowly drain will sulfate a battery faster than a Kardashian running after money.
Test that battery!! It may be SO discharged that the alternator cannot keep up.
Also alternator make very POOR battery chargers.
