Bleeping anectdote

My 97 did a strange thing today. Its been sitting a while and the battery was really weak and barely turned the motor over.
When it did start, the spoiler extended and the temp gauge that I had the dealer turn on read mph - - - instead of temp.
What is going on?

The low voltage of the battery, combined with the heavy draw of the starter, caused the car's computer to reset and some things went haywire. It's never a good idea to start a modern car on a low battery.

Once while working on my 88 CRX with the driver's door open, the radar detector started bleeping. I looked around for a police car, but nothing. This went on for a while with no evidence of police near by, so I just shut it off. I had the door open for several hours when I noticed the dome light was very dim. The car barely cranked, but started, so I left it running a while. When I turned on the detector there was no more bleeping.

Electrons are elusive. Our FD Freightliner Tanker truck will sound its brakes low air alarm when the portable radios are keyed. Disconcerting until you know what is happening. The radios have also opened the the fire house doors occasionally.

Ed B in warm (25F) and sunny NH

Removed the battery from the car. It is about three years old and had it tested. It checked out OK and we left in on the charger for about 20 minutes. Put it back in and my Temp gauge display returned and the car runs smoother than before. I have a Tip so the computer and probably other systems reset themselves.
The spoiler also appears to be behaving and staying put .
I can only guess I let the battery drain and go down too low.

My Turbo was slow cranking -- out of character -- but with no other symptoms. Interstate Battery in the car when I bought it, age of battery unknown. Could have accessed the battery and looked but I was too lazy.

Took the car (car still under CPO warranty) to the dealer. Tech tested the battery. Tested ok. Let car sit a few hours and tested it again. Battery down by IIRC 40%. New battery time. Oh, battery is a consumable and not covered by CPO warranty. Oh^2. Service department installed another Interstate battery. The dealer used to stock only OEM batteries -- I bought one from the dealer for my Boxster about 2 years ago -- but switched over to using Interstate Batteries.

Happy New Year!

Sincerely,

MarcW.