@Uzer That's close to what I had with my Solo when I first got it. Around 2 hours of battery life. I still probably get 7 - 12 min sessions with my Solos and 1 is 6 months old and the other is about 8 months.
I've been trying to adhere to
@OF s advice about taking care of ones battery. My fav temp is heat level 4 and then bump up to 5 at the end of my session. I go higher with the D020 bubbler.
I'm very happy with the battery life with both units. One of the Solos I bought for $55 through Puffitup. It was one that had been sent back and repaired, so really the one that's 6 months old could be older. They are both the 2014 models. Look every so often at Puffiup it's called a Last Call sale, you'll see it.