Okay it's 10 years old, the battery in my S2000!
Kept it on the charger all winter, she started right up... Kind of, sputtered and spurted a bit before starting. Assumed, bad gas maybe....
Well wouldn't start a day later, doh. Quick boost with the Yaris and it cranked over without the sputtering it was doing with the weaker battery. 10 years, it is done, it did well.
Time to go shopping!