Battery Discharge Calculator Formula

Understand the math behind the battery discharge calculator. Each variable explained with a worked example.

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Formulas Used

Discharge Current

discharge_current_ma = capacity_mah / target_hours

C-Rate

c_rate = 1 / target_hours

Energy Delivered

energy_wh = capacity_mah * nominal_voltage / 1000

Variables

VariableDescriptionDefault
capacity_mahBattery Capacity(mAh)5000
target_hoursTarget Discharge Time(hours)10
nominal_voltageNominal Voltage(V)3.7

How It Works

Battery Discharge Rate

Formulas

I_discharge = Capacity / Time

C-rate = 1 / Time(hours)

Energy = Capacity x Voltage

A 1C rate discharges the battery in 1 hour. 0.5C takes 2 hours. 2C takes 30 minutes.

Worked Example

5000 mAh battery to be discharged in 10 hours.

capacity_mah = 5000target_hours = 10nominal_voltage = 3.7
  1. 01Current = 5000 / 10 = 500 mA
  2. 02C-rate = 1 / 10 = 0.1C
  3. 03Energy = 5000 x 3.7 / 1000 = 18.5 Wh

Ready to run the numbers?

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