Okay, so! Car won't start.

* It ran just fine yesterday.
* Today when I turn the key to start, there is very slow cranking for a second or two, but it changes to repetitive clicking, with the dash lights flickering along with it. Classic low battery symptom.
* Battery reads 12.55 V. Could be higher, but should be fine. Accessory power is working normally.
* It was -5 to -10°C today, and this car has no block/battery heater. Could be too cold to push enough starting amps.

🧵1/?

* I tried jump-starting with another, running vehicle. It made no difference. I let the donor car run for 10 minutes, which I would hope might warm up the recipient battery a bit. *Still* no difference at all.

I can't rule out the cold temperature (or that it's probably an old battery), but I'm really surprised that jump-starting had no effect at all (and I had good sparking on the jumper cables, I'm pretty sure those were hooked up properly). I'm worried it's a bad starter or wiring. 😮‍💨

🧵3/

Today is warmer, but still -2°C. The battery read 12.3 V this morning, surely having been depleted by my futzing around yesterday. I lack a charger, and
I didn't want to keep troubleshooting without being certain of the battery's state, so I figured I needed to bring it to a shop for testing.

And only when I pulled it out of this 2013 Mazda did I realize it's the original from the factory (since the only English written anywhere on the battery is "Panasonic"). So yeah, 12 years old...