Well, I just got WheelWorks (battery dealer) to check the electrical system
and I did further analysis.


~Prior to going to the dealer, I jump started the car and drove hiway for 20 minutes and the reat of the 20 minutes was street driving and car idling while I waited to be attended.


3PM 24-Nov-06
Wheelworks used a medium-large sized hand held digital apparatus to first check the battery voltage and cranking power with car off. He said battery was marginal. I asked if battery had an internal short, he said he could not tell (later I reasked after he did the load test and he said the meter showed no int. short. He did seem to understand better that time...). He said its cranking power of 8 amps (?) was not up to par. Basically he assured me that once it charged up, it would be good. So far no premise for new battery under warranty.

To my surprise, the car started up for the rest of the tests.

He checked the charging system without load it was 13.74 V , with load (lights on and air blower on-not AC) it read 13.45V.
(remember the car had been running 40 minutes prior to test in order to catch any faults with a hot system).

He tested the alternator and starter by way of the apparatus and claimed they were good, no shorts etc.

Back home with car still idling I did some more checks with my Fluke multimeter.

3:25 PM

At idle, 13.73V alt. charging.
At high idle the meter read up to 13.94V

With the car off and battery cables still on, the battery at rest read 12.55V immediately after shutting car off.

Three minutes later after taking the cables off the battery posts read 12.48V
with cables quicky pressed on I got 12.48V-- no difference.

After another 4 minutes at 3:34PM battery w/o cables read 12.45V
At 3:35PM it read 12.44V
At 3:39PM it read 12.43V
At 3:43PM it read 12.42V

I stopped here. I will get a reading a few hours later to see if it drops significantly before attaching the 1 Amp battery charger overnight.


The other tests I made prior to shutting the car off were:

All external lights work. No burnt bulbs. Trunk light OK switch works.

The main trunk light read 12.96V across the bulb with car running.
The two horizontal lights on the trunk end-lip (safety lights for when lid is up at night) read -0.047V across the bare terminals each.
With headlamps on, these terminals read 12.38V
(I removed the bulbs to these lid lamps because they looked dark but filaments were whole. Did not test bulbs but remain uninstalled)

Glove box light terminals with car idling, read 13.57V (is this high?)
With the glove box light switch depressed the mater read 0.008V across the terminals.

~~~~~~~~~ Question so far, does a standing battery that is marginal , lose volts soon after the car is shut off or should it float within a certain margin of volts?

I plan to check the reading after a few hours to see how much more it drops if any.

EDITED-- At 6:45PM the battery read 12.32V A 0.10V drop in three hours.

A fully charged battery is supposed to float at some said volts. What is the margin of voltage loss just standing without cables attached??

Thank You.

Denis

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD