[MattW]

I went out to the local Red Cross to give them a pint of O+ goodness yesterday. This weekend always seems like a great time to give, every year.

No good deed, etc. Came back out to the car 35 minutes after parking, and I had a totally dead system - no SECURITY light, no IP test, no switch or starter click - and an odd buzzing noise from one of the relays in the footwell fusebox when I opened the right door. But the column lock solenoid could still be heard to cycle, the mirror reading lights still worked.

I got a jumpstart, and drove out to an Autozone. The whole time, my Voltmeter was fluctuating a lot. Could hear the occasional buzz/sizzle from the footwell fusebox and the voltmeter needle would dip every time a buzz was heard.

Volts would go from 12.5 down to as low as 7.9, especially idling at traffic lights. It would drop so low the airbag dash light would blink, and I set several BCM, LDCM and RDCM codes.

Got to Autozone, got diagnosed with a bad battery (of course).

Replaced battery with a "better" battery than had been in the car.

Now, I'm paying a lot of attention to the Voltmeter. When I'm running the car, the volts are staying at a solid 13.2. Idling at traffic lights, the voltage falls slowly... 13.0.... 12.7... 12.5... haven't seen it fall below 12.5.

Don't hear any more buzz/sizzle from the footwell fuse/relay box at all.

...when I crank the car, the car starts up quickly, no hesitation. Started it four times today.

But... the voltmeter needle, on cranking, swings all the way over into the 8-9 volt range. As the car idles, it slowly comes back up to 12+ volts, perhaps over the course of 6-10 seconds.

Is this "normal" behavior for a start event? I never paid attention before, and now I'm paranoid.