Hours of run time from capacity in mAh and a steady load in mA.
| Hours | – |
Use this calculator for a rough estimate of how long a pack lasts at a constant current: a bank, a light, or a small gadget.
Hours = capacity (mAh) ÷ load (mA). 3000 mAh at 150 mA is 20 hours. Real packs are not emptied to zero, and voltage sag shortens the useful time. Capacity in watt-hours needs a voltage as well; this form is current only.
Capacity (mAh): Battery capacity in milliamp-hours.
Load (mA): Average current draw, not zero.
Hours: Estimated run time.
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