Tracking down a battery drain

[Huw Powell]

On 9/29/2010 12:22 PM, TooManyAudis at aol.com wrote:
> Took the car to Advance Auto last night, had them do a charge on the
> battery, then a system test.
> Existing battery (4 years old -- Huw incorrectly guessed at its age
> being 6 years, resulting in 4 demerits) was putting out 500 +/- amps,
> with it being rated for 700 amps new.

I guessed based on the MY of the car.  So it needed a new battery after 
two years?

Anyway, so it tested "good"...

> Put in a new battery for $100. Rated at 850 amps with 700 cold cranking
> amps. Started strong this morning.

...so why put in a new one?

> The salesman at Advance did a charging system test after the install of
> the new battery. Results are:
> 1) Battery: 12.56v; measured at 817 CCA, rated at 700 CCA; Temp: 79
> degrees f.; Good Battery
> 2) Starter Test: Voltage: 10.99v; Amps: 215.8A; Time: 1.03 seconds;
> Cranking Normal.

200 amps is a bit high.  Like double what it should be, I think, though 
I don't know your engine.  I once had a hot start problem on my coupe, 
starter was drawing 200 A, replaced, problem went away.

> 3) Charging System Test: No load: 14.00v, 4.4A; Loaded: 13.47v 2.4A: No
> Problems
> 4) Drain Test: 0.45A: Pass

As everyone else said, that seems a bit high.

> With # 3, my Instrument cluster voltmeter showed right around 12v with
> the high beams on and AC on max during this test. Is there an
> explanation for the difference. Is the IC voltmeter picking up voltage
> after the radiator fan, blower fan and compressor clutch?

The blower fan is probably raising the IC ground a bit.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/