I am thinking you are measuring reference voltage to an A\F O2 sensor. Reference voltage is usually between 2.5 and 4 volts. If there are 4 or more wires, this is most likely the case. Also A\F sensors don't oscillate like traditional sensors.
A voltmeter can tell you part of the story.
The second part is twofold. One is how much your battery can deliver in the cold. Cold cranking amps means worse case senerio.
Two is how long that battery can deliver some amount of current over time.
Usually both figures are published on the battery or someplace. One tends to be more important over the other ...