Well, I'm finding an operation time of ~46 hours, although the battery life was supposedly 60 hours. I did find this tidbit[1]:
"Shortly after passing into daylight, the Vega-2 aerostat plunged several kilometers, to a level of 0.9 atmospheres, dangerously close to the lower limit of its stable float zone. After the end of signal, the balloons probably overheated and burst, somewhere on the daylight side of Venus."
