Yes, the battery meter is at times close to useless. It'll say 25% one minute and then be at 0% the next minute. If you plug it in, it'll magically charge from 0% to 40% instantaneously.
Just run it until it shuts off, and then charge it until it says it's fully charged and ignore the battery meter for now and see how many days you get on a full charge. I got 18 days on my Libra 2 last time, so now I'll try to be more gentle with the battery for the next few charges, and if the meter goes completely wonky again, I'll do another full charge/discharge.