Formula
Ideal hours are capacity divided by current. Efficiency makes them longer:
hours = mAh / mA / efficiency
The runtime page discharges into watts. This page fills the cell from a milliamp current.
Assumptions
- The current stays at the number you type.
- Efficiency is the share of that current that becomes stored charge.
- The battery starts empty.
Worked example
A 10,000 mAh battery charged at 2,000 mA with 85% efficiency takes 5.88 h.
Input definitions
- Charge current
- The milliamps the charger delivers.
- Charge efficiency
- The percent of those milliamps that end up stored.
Limitations
This is a planning figure from the numbers you type. It is not a measurement of a network, a camera, a printer, or a power supply.
Questions
Why is the result longer than 10,000 divided by 2,000?
Five hours would be a perfectly efficient charge. At 85% the same current takes longer.
Does this model the taper at the end of a charge?
No. The current is constant. A real charger may slow down near full.