Electronics
Runtime from amp hours
The ideal runtime before depth of discharge and rate effects.
The Formula
runtime hours = amp hours x volts / watts
The ideal runtime before depth of discharge and rate effects.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| Ah | Capacity | amp hours | The nameplate capacity in amp hours. |
| V | Voltage | volts | The nominal pack voltage. |
| W | Load | watts | The power the load draws. |
| t | Runtime | hours | The hours the pack can supply the load. |
What Each Symbol Means
Ahamp hours
Capacity
The nameplate capacity in amp hours.
Vvolts
Voltage
The nominal pack voltage.
Wwatts
Load
The power the load draws.
thours
Runtime
The hours the pack can supply the load.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate battery life page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Battery Life, filed under Science. Every number the guide produces comes from substituting into this one line.