@Cheesequake - Did you purchase from a retailer or purchase direct from Arizer? Hopefully you purchased from one of the much loved retailers like PotV or PIU.
I had a new Solo start giving me battery issues before the warranty expired. When I first got it I noticed the battery life wasn't nearly as good as my almost 5 year old Solo. It was still acceptable when new but I also noticed it was doing some weird things like skipping a battery level all together on the way down. After several months it was way worse but Arizer said it was acceptable degradation or within their acceptable range. At this point the battery lights were working even more strangely (Level 7 wouldn't light up anymore and entire levels where skipped) and battery life wasn't dependable. Had to go to PotV to get it replaced. I never used the Solo while charging, etc.
Lesson learned....I never purchase directly from the manufacturer unless they are the only place to go AND their reviews imply good customer service.