The meter goes into a low power mode when data logging. I was hoping to finish off the battery this weekend but it still has a fair amount of charge left.
I put the meter into my temperature chamber
(cardboard box with two layers of foam, fan and heater). Normally I run this off a PC but for this, I just ran it open loop, using the Brymen to monitor the temperature next to the meter.
I started out at room temp (21.4C). I then just set the heater to a fixed current. At 18 minutes, it was at 32.2 C. At 1 hour it reached 34.2 C. At least a 10 deg rise.
After three days of testing and around 30 hours of hard time, the last picture shows the battery remaining. They do not talk about the battery life but I would guess based on my normal use, its about 40 hours between charges.