Battery Life
9h 0m
Wh
18.5
Draw
1.85W
Estimated Runtime
9h 0m
540 minutes total
Effective mAh
4500
Watt-Hours
18.5
Draw (W)
1.85
Inputs
Result
Effective capacity = 5000 × 0.90 = 4500 mAh. Runtime = 4500 / 500 = 9 hours.
Inputs
Result
Effective capacity = 60 × 0.92 = 55.2 mAh. Runtime = 55.2 / 30 = 1.84 hours = 1h 50m.
Divide the battery capacity in mAh by the device current draw in mA. A 5000 mAh battery powering a 500 mA device lasts about 10 hours. Factor in efficiency losses (10–30%) depending on battery chemistry.
| Battery Type | Efficiency | 5000 mAh @ 500 mA | Effective Runtime |
|---|---|---|---|
| Li-Ion | 90% | 10 hrs ideal | 9 hrs |
| NiMH | 80% | 10 hrs ideal | 8 hrs |
| Alkaline | 70% | 10 hrs ideal | 7 hrs |
| Lead-Acid | 75% | 10 hrs ideal | 7.5 hrs |
mAh (milliamp-hours) measures charge capacity, while Wh (watt-hours) measures energy. To convert: Wh = mAh × Voltage / 1000. A 5000 mAh battery at 3.7V = 18.5 Wh. Airlines limit carry-on batteries to 100 Wh.
Average smartphone current draw is 300–600 mA during normal use. Screen-on browsing draws ~500 mA, idle/standby draws ~30–50 mA, gaming or GPS can draw 1000–1500 mA. Actual draw varies by screen brightness, processor load, and radio activity.
Yes. Lithium batteries lose about 20% capacity after 500 charge cycles. After 2–3 years of daily charging, a 5000 mAh battery may only deliver 4000 mAh. Heat and deep discharges accelerate degradation.
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Last Updated: Jun 11, 2026
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