Power & Battery Planner

Energy stored in a battery is Watt-hours = (mAh × V) ÷ 1000. For each device you multiply its full Wh by the share of the battery you drain per day, then sum across devices. A 1.3× efficiency / safety factor accounts for converter loss, voltage conversion, cold-temperature derating and ageing cells. Power-bank capacity is quoted at its cell voltage (~3.7 V): 10,000 mAh ≈ 37 Wh, 20,000 mAh ≈ 74 Wh, 30,000 mAh ≈ 111 Wh.电池储存的能量为 瓦时 = (mAh × 电压V) ÷ 1000。每台设备按其每天消耗的电池比例乘以满电 Wh，再把所有设备相加。再乘以 1.3 倍效率/安全系数，以覆盖升压转换损耗、低温掉电与电池老化。充电宝容量按电芯电压（约 3.7 V）标注：10,000 mAh ≈ 37 Wh，20,000 mAh ≈ 74 Wh，30,000 mAh ≈ 111 Wh。

dailyWh = Σ (mAh × V / 1000 × %use/100)

needWh = dailyWh × days × margin

Sources: basic electronics (Wh = mAh×V/1000); power-bank Wh ratings as printed on certified products; 1.3× margin is a common outdoor-planning rule of thumb. Always verify the Wh rating printed on your actual battery — it also matters for airline carry-on limits.