After a recent trip, I started learning how to shoot star trails. Found several helpful posts but also worry about OM-D battery life. So did some tests using my intervalometer set to give a 359 sec. exposure every 360 sec. First the good news. With everything you can turn off set to off (IS, AF, screens, MF assist, AF Illuminate, Noise Reduction, Full Time AF, Face Priority, Frame Rate Normal, etc.), I got 52-53 exposures from a fully charged 6 mo. old Olympus battery or 5 hrs 5 min. Ran 2 tests at about 65F & one @ 45F. No difference in battery life. Now the bad news. In 3 tests, the Wasabi 3rd party batteries only gave 21-22 exposures or 2 hrs 5min. These were charged in the Wasabi charger while the Olympus batteries were charged in the factory charger. So the factory batteries will easily last long enough at least in mild conditions to shoot star trails when fully charged & camera set to its lowest power consumption state. That last condition is important. By accident, I left IS on for one test & that alone cut battery life by about 60%. Really cold conditions are likely to significantly reduce battery life. If I find that does happen, I'll try using a rubber band to hold a small chemical hand warmer on the camera battery door to keep it warm. Hope you find this helpful!