电池寿命计算器
输入电池容量（mAh）和设备耗电量（mA），即时估算运行时间。切换到所需容量模式，可计算达到目标运行时间所需的最低 mAh。调节效率滑块以匹配您的电池化学类型和工作条件。
Real-world batteries deliver 70–90% of rated capacity. Default 80% accounts for discharge curve losses.
常见问题
如何根据 mAh 计算电池寿命？
电池寿命（小时）= (电池容量（mAh）× 效率) ÷ 平均电流消耗（mA）。例如，2,000 mAh 电池以 80% 效率为 200 mA 设备供电，续航时间为 (2000 × 0.8) ÷ 200 = 8 小时。效率因子（通常 0.7-0.9）考虑了放电曲线损耗、温度影响和电池老化——实际电池永远无法提供额定容量的 100%。
电池上的 mAh 是什么意思？
mAh 代表毫安时，是电荷的单位，表示电池存储的能量。3,000 mAh 电池理论上可以持续提供 3,000 mA 电流 1 小时，或 300 mA 电流 10 小时。mAh 越高表示存储的能量越多，假设设备电流消耗相同则续航越长。注意，mAh 本身不代表总能量——3.7 V 的 3,000 mAh 电池存储的能量远多于 1.5 V 的同等容量电池。
为什么电池效率低于 100%？
实际电池因多种因素而失去可用容量：(1) 放电曲线——电池耗尽时电压下降，大多数设备在电池完全耗尽前就停止工作；(2) 温度——寒冷天气可使容量降低 20-50%；(3) 年龄和循环次数——可充电电池约 500 次完整充放电后容量降低 20%；(4) 自放电——电池在不使用时也会自动放电。80% 默认效率是大多数锂离子应用的安全保守估算。
AA 电池能用多久？
全新碱性 AA 电池约有 2,400-3,000 mAh。以 80% 效率和 200 mA 负载计算，续航约为 (2400 × 0.8) ÷ 200 = 9.6 小时。对于电视遥控器等极低功耗设备（约 1 mA 平均消耗），同一块电池可以使用 1,900 多小时。续航时间很大程度上取决于电流消耗——在上方计算器中输入你设备的实际消耗以获得准确估算。
24 小时续航需要多少 mAh？
所需容量（mAh）= ⌈ (电流消耗 × 目标小时数) ÷ 效率 ⌉。对于消耗 100 mA 的设备，目标 24 小时，80% 效率：(100 × 24) ÷ 0.8 = 3,000 mAh。使用上方计算器的「所需容量」模式可自动计算。设计时始终增加 20-50% 的余量，以应对电池老化和最坏情况的温度条件。
mAh 和 Wh 有什么区别？
mAh（毫安时）衡量电荷，而 Wh（瓦时）衡量能量。转换公式：Wh = mAh × 电压 ÷ 1000。3.7 V 的 3,000 mAh 锂离子电池存储 3000 × 3.7 ÷ 1000 = 11.1 Wh。Wh 是比较不同电压电池的更好指标，也是航空公司用于随身携带电池尺寸限制的单位。对于单一电压系统，mAh 足以用于续航时间计算。
如何测量我的设备的电流消耗？
最直接的方法是将设置为直流 mA 的万用表串联接入电源线。对于包括睡眠模式和突发功耗在内的详细分析，专用电源分析仪（如 Nordic Power Profiler Kit II 或 Otii Arc）可捕获微秒级电流追踪并计算平均消耗。查阅元件数据手册的典型和最大供电电流数据，并将所有活跃元件相加，以在实际测量前估算总功耗。
寒冷天气会降低电池容量吗？
是的，显著降低。锂离子电池在 0°C 时容量约降低 20%，在 -20°C 时降低 40-50%，因为内阻增加减缓了电化学反应。碱性电池受影响更大，在冰点时容量损失高达 50%。对于户外或低温环境应用，在计算器中使用较低的效率值（60-70%），并考虑使用加热外壳或锂一次性化学电池（在极端寒冷中性能优于可充电电池）。
Battery Life Calculator: How to Estimate Runtime from mAh & Current
The Battery Life Calculator estimates how long a battery will power a device based on its capacity in milliamp-hours (mAh) and the device's average current draw in milliamps (mA). It also calculates the minimum battery capacity required to meet a target runtime — essential for embedded systems design, IoT deployments, portable electronics, and emergency backup planning.
Contents
Battery Life Formula
The core formula for estimating battery runtime is straightforward:
Runtime (hours) = (Capacity × Efficiency) ÷ Current Draw
- Capacity — battery rated capacity in mAh
- Efficiency — usable fraction (0.0–1.0, typically 0.8)
- Current Draw — average device consumption in mA
Example: A 3,000 mAh lithium-ion cell powering a 250 mA circuit at 80% efficiency:
To find the minimum capacity needed for a desired runtime, rearrange the formula:
Efficiency Factors
No battery delivers 100% of its rated capacity under real-world conditions. Several factors reduce usable capacity:
Discharge Curve Losses (5–15%)
Battery voltage drops as charge depletes. Most devices have a minimum operating voltage cutoff, leaving some charge inaccessible. This is the primary efficiency loss for lithium and alkaline chemistries.
Temperature Effects
Cold temperatures reduce capacity significantly — a lithium cell can lose 20–30% capacity at 0°C and up to 50% at −20°C. High temperatures accelerate aging and self-discharge. Use a lower efficiency figure for outdoor or cold-chain applications.
Battery Age & Cycle Count
Rechargeable batteries degrade over charge cycles. A lithium-ion cell at 500 cycles typically retains only 80% of original capacity. For aging cells, reduce the efficiency figure accordingly.
Self-Discharge
All batteries lose charge while idle. Alkaline cells self-discharge about 2% per year; NiMH up to 20% per month; lithium-ion about 2–5% per month. For long storage periods, account for self-discharge when sizing a battery.
Recommended Efficiency by Chemistry
| Chemistry | Typical Efficiency | Notes |
|---|---|---|
| Lithium-Ion (Li-Ion) | 80–90% | Flat discharge curve, good efficiency |
| Alkaline (AA/AAA/9V) | 70–85% | Voltage sags under load |
| NiMH | 75–85% | High self-discharge reduces effective capacity |
| LiFePO4 | 90–95% | Very flat curve, long cycle life |
| Lithium Primary (CR2032) | 75–85% | Very low self-discharge, good shelf life |
Common Battery Capacities
Use this reference table to quickly select the right battery for your application or to verify datasheet values when using the calculator.
| Battery Type | Typical Capacity | Voltage | Common Use |
|---|---|---|---|
| AA Alkaline | 2,400–3,000 mAh | 1.5 V | Remotes, clocks, toys |
| AAA Alkaline | 1,000–1,200 mAh | 1.5 V | Small remotes, LED lights |
| 9V Alkaline | 500–600 mAh | 9 V | Smoke detectors, effects pedals |
| CR2032 (Lithium coin) | 210–240 mAh | 3 V | Watches, RTC, key fobs |
| 18650 Li-Ion | 2,500–3,500 mAh | 3.6–3.7 V | Laptops, flashlights, power banks |
| 21700 Li-Ion | 4,000–5,000 mAh | 3.6–3.7 V | EVs, high-drain devices |
| Smartphone battery (typical) | 3,000–5,000 mAh | 3.7–3.85 V | Mobile phones |
| LiPo 1000 mAh | 1,000 mAh | 3.7 V | Drones, RC vehicles, wearables |
Capacities are typical rated values at 0.2C discharge rate at 25°C. Actual values vary by manufacturer and discharge rate.
Tips for Maximising Battery Life
Reduce Peak Current
Use sleep modes and duty cycling to minimise average current. A microcontroller drawing 50 mA active for 10% of the time averages only 5 mA — a 10x improvement.
Use Efficient Regulators
Linear regulators waste the voltage difference as heat. Switching regulators (buck/boost) achieve 85–95% efficiency. This directly improves effective battery life.
Measure Actual Current
Use a multimeter or power profiler (e.g. Nordic PPK2) to measure real average current draw. Datasheets list typical values; your circuit may differ.
Add a Safety Margin
Design for 120–150% of the minimum required capacity. This accounts for battery aging, temperature variation, and unexpected load spikes.