A votage regulator producing 14.5V is perfectly okay. Measured at the back of the alt between battery B+ and the D- ground terminal, the Volvo spec at 2500 rpm for the later alts is 13.8V-14.6V on the car with a minimal battery load and 14.1V-14.9V on the bench with no load. More commonly you'd expect to see closer to 14.25V at the alt, a bit less with loads on or a charging battery, a bit less still if measured at the battery posts (cable/connection voltage drop). I usually want to see around 13.25V-14.25V measured at the battery at >1700 rpm with minimum loads and no less than 12.5V with all loads on and a battery in only average condition. My first suspicion here would be an older battery that can't cope with winter temps combined with a slightly less than accurate voltmeter.

For others reading here, the nominal voltage for a lead acid battery in perfect condition at normal ambient temps is 2.2V per cell, but in practice it's typically 1.8V-2.1V depending on the charge. So, between posts and disconnected you'll typically see that 12.6V you mentioned, while as low as 10.8V can be considered acceptable for an almost discharged battery. As a battery ages as low as 12.2V is generally considered acceptable when fully charged.

Batteries need to be charged then load tested to determine their health and ability to hold a charge. I find the starter motor sounding weak and/or longer cranking after one week of the car sitting is one of the more reliable ways to know when a battery needs to be replaced.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now