Battery Runtime Calculator
Estimate portable-station operating time from battery capacity, radio current and transmit duty cycle.
This estimates runtime from average current. Real runtime depends on battery chemistry, temperature, discharge rate, converter losses and transmit duty pattern.
Plan for duty cycle and battery margin
Battery runtime is an energy-budget estimate. Transmit current usually dominates for voice operation, while digital modes and long receive periods can produce a very different average load.
Use the actual radio current figures from the manufacturer when available, and include conversion losses for DC-DC converters or inverters. Leave a practical reserve instead of planning to drain a field battery completely.
For portable operation, measure one representative operating session if possible. A real duty-cycle measurement is more valuable than assuming that the radio draws full transmit current continuously.
Use the result when planning a portable session
A battery-runtime estimate is most useful when the radio's actual operating pattern is known. A transceiver may draw a modest current while receiving and a much larger current while transmitting, so a simple full-power figure can overstate or understate practical endurance. Enter the supply voltage and the relevant load values, then account for transmit duty cycle rather than assuming continuous transmission. A reserve is sensible for portable work because nominal battery capacity is measured under specified conditions and may fall with temperature, age, high discharge rates or an unsuitable cutoff voltage. DC-DC converters and other accessories also consume power, so include them when they share the battery. The result should be read as an estimate of usable operating time, not as a guarantee that the radio will remain within its preferred voltage range for the entire period. Before an important activation, test the actual station under a representative load and record the current drawn from the battery.