This is not normal for this phone. I think you should ask for help on the forums or by email. Examples:
https://forums.puri.sm/t/modem-draining-the-battery-very-fas...
https://forums.puri.sm/t/modem-draining-the-battery-very-fas...
I've had the phone for a while and the battery has gone through many cycles. It has definitely lost some capacity.