t = H * (C / (I * H))ᵏ
t = Time (Hours)
H = Rated discharge time = 20 (Hours)
C = Capacity (Ah)
I = Load (A)
k = Peukert constant (1 - 1.5)
This calculator estimates the theoretical runtime of a battery under a given load. By entering battery configuration and load parameters, you can determine the expected duration of power supply.
Select the battery connection type:
Series: Voltages add up, capacity remains unchanged
Parallel: Voltage remains constant, capacities add up
Total number of batteries in the system. The total voltage and capacity are calculated based on the connection type.
Voltage (V)
Nominal voltage of a single battery, in volts (V).
Capacity (Ah)
Rated capacity of a single battery, in ampere-hours (Ah).
Load (W or A)
Power consumption of the connected device. Two input options:
Power (W): In watts, suitable for most appliances
Current (A): In amperes, when operating current is known
A coefficient used to correct for capacity loss at higher discharge rates. Typical values by battery type:
Lead-Acid: 1.1 – 1.3
Gel: 1.1 – 1.25
Flooded: 1.2 – 1.5
Lithium-Ion: 1.0 – 1.28
An ideal battery has a Peukert constant of 1.0. Real batteries have values greater than 1.0, which typically increase with age.
The percentage of battery capacity that has been discharged relative to full capacity.DoD = 100% - SoC (State of Charge).
Can be expressed in percent (%) or ampere-hours (Ah). In some cases, actual capacity exceeds rated capacity, so DoD may exceed 100%.
Calculator outputs are theoretical estimates. Actual runtime is affected by battery aging, ambient temperature, transient peak loads and cable losses. Incorrect settings for Peukert constant and Depth of Discharge also create deviation between calculated and real discharge duration.
Depth of Discharge (DoD) is the percentage of total rated capacity drawn from the battery. Higher DoD gives longer calculated runtime yet accelerates cycle aging. Each battery chemistry has its recommended maximum DoD; avoid continuous deep discharge in practical operation.
Use power (W) mode if you know device power consumption. Use current (A) mode when operating current is measured directly. Both inputs should yield consistent results. Ensure input values match the total battery‑pack voltage; mismatched parameters produce incorrect runtime estimates.
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