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Battery life is calculated from capacity (mAh), discharge current (amps), and voltage. Watt-hours = mAh × Voltage ÷ 1000, and runtime = Watt-hours ÷ Power draw (Watts).

الصيغة

Runtime(hrs) = Capacity(mAh) ÷ 1000 ÷ Current(A) × Voltage(V) | Watt-hours = mAh × V ÷ 1000
C
Battery Capacity (mAh)
I
Discharge Current (A)
Wh
Energy Capacity (Wh)

دليل خطوة بخطوة

  1. 1Runtime (hours) = Capacity (mAh) ÷ 1000 ÷ Current (A) × Voltage (V)
  2. 2Watt-hours = mAh × V ÷ 1000
  3. 3Real runtime is 70–80% of theoretical (efficiency losses)
  4. 4Temperature, age, and load affect actual capacity

أمثلة محلولة

الإدخال
5000 mAh at 3.7V, 0.5A draw
النتيجة
37 Wh, ≈10 hours theoretical runtime
الإدخال
Phone battery: 4000 mAh at 3.85V, average 1W usage
النتيجة
≈15.4 Wh → ≈15 hours

أسئلة شائعة

Why is real runtime less than calculated?

Efficiency losses from internal resistance, voltage regulation, and management circuits typically consume 20–30% of theoretical capacity.

How does temperature affect battery life?

Lithium batteries perform best at room temperature. Cold temperatures reduce effective capacity; heat ages the battery faster.

What is battery cycle life?

A cycle is one full discharge and recharge. Most lithium batteries last 500–1000 cycles before capacity degrades to 80%.

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