I get 85-90 minutes consistently whether it's the H520 or the E-RTK. Less flight time on the RTK due to waiting for satellites and a fix. I carry 3 batteries at all times and have the 3-port charger.order the last part auto low voltage cutoff circuit. been manually observing the voltage and cutting it off at 15.1 volts. which is enough runtime for up 8 full flights at 20 min each or 6 full flights at 25 min each. with power to spare. which is 50 percent storage level with the h520 flight battery.