Low voltage in battery, all the time

[SJ]

> From: pasquale pilato <pasqualep99 at yahoo.com>
> Subject: Low voltage in battery, all the time


Use the built in A/C control head diagnostic channels to show the actual
alternator voltage when driving.

To activate this function:
1. Ignition ON
2. Push and hold "Outside temp" button
3. Push and hold "Off" button
4. Release "Outside temp" button
5. Release "Off" button

6. Select the channel by pressing "warmer" or "colder" buttons.
    Channel 11 is the "Vehicle electrical system voltage" channel

8. To call up the info for that channel, press "Outside temp" button.

To leave this diagnostic funcion, select any A/C operating mode, or switch
off ignition.

> I have almost 14v on the dash voltmeter
**** Normal voltage.

>Some more info, when I'm driving, and the lights are on, and the stereo
cranked, the dash voltmeter drops to a hair above >12v. (have a 1 farad
capacitor to install)
**** Use the A/C diagnostic channel, it is more accurate.
Your stereo may be a bit much for the alternator. The alt was not built to
handle a 1000 watt stereo. Do not use the stereo during diagnostic period
when you are troubleshooting the problem.

> What I don't know is if the battery can't hold a
> charge, it is new and still under Sears warranty.
**** Battery should read about 12.8 volts when fully charged. Put a
load(parking lights on, door open) on the battery for about 10 seconds to
bleed off the surface charge before making a voltage reading. If the battery
reads 12.0 volts, it is dead.
Also, read the voltage at the battery, when engine is running. The battery
voltage should match what the A/C control head is displaying.
Check to see if you have enough water in the battery.

 >Or if the alternator is not making enough charge,
**** "14v" on the voltmete says its charging.

>or if I  have a leak in the air compressor system, and that
> thing runs all the time draining the battery.
**** air compressor? You mean the A/C compressor?
Use "economy" on the A/C conrol. This will not use the A/C compressor.
Test to see if compressor is turning with engine running. If it is, you can
disconnect the compressor clutch wire. There is a connector there, follow
the wire.

And last but not least. Check to see if something is draining the battery
with ignition off.
My preferred method is to disconnect the battery ground and place a 10 watt,
2 ohm resistor between ground strap and battery. Measure the voltage drop
across resistor. Use the formula I = V/R to calculate the current.
Make sure, the inside door lamps are all shut off. Easiest way is to close
the door and have someone outside lock the doors.

Yes, you can use an ammeter to check for drain. But, most folks will just
blow out the ammeter doing this if the current is high.

If I remember correctly you will see about a 60 milliamp (.060 amps) drain
on the battery. Some stuff is always on, like radio memory, etc.
If you have more current that this. Start pulling fuses to isolate the
problem.

****WARNING !!!
Your radio(original) will not work again if you disconnect the battery. You
need to put in a code to get the radio working again. You get the code from
the dealer. I think you need to give him radio serial number. This
information should be on a sticker in the trunk lid.
If you need the procedure to input the code, let me know.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q