My clock is losing like a minute a day and our old friend Google leads me to believe it could be the battery. Can anybody confirm this please. If so, the battery could well be the original battery and would be 8 years old. The writing on it says: 12V 80AH 800A (EN) 140 RC 800 CCA (SAE) I can see plenty of 80 AH - 720 CCA but not many 80 AH - 800 CCA which seem to be much more expensive. Do I have to replace like for like?