It does not take alot of battery power to run it.. it will last you along time. It is just like running a watch. It does not take alot to measure all the data as alot of it has to do with the magnet sensor at the wheel and fork. As the magnet pass the sensor on the fork with every rotation, it is sending that magnetic flux which is picked and calculated by the display unit on your handle bar. Easily one year of use lah..... more if you are careful not to damage it or subject it to any big change in temperature..etc.