Radon Monitor with extended life battery

I recently purchased a used Sun Nuclear 1027 continuous radon monitor. Per the manual, an alkaline 9V will provide up to 20 hours of battery back-up. But what about those houses without electricity or where electrical cords could become a trip hazard? I tried the Ultralife 9V batteryand got 83 hours of battery-only run time. I bought this battery at Radio Shack for about $10. I’m sure there are other extended batteries out there but I just happened across this one at Radio Shack.
I am not affiliated with this battery company, but just wanted to share an option for users of the Sun Nuclear 1027.