Short Discharge Time

Short Discharge Time (SDT) is a constant characteristic of each battery cell technology, regardless of capacity or voltage, that allows fair comparisons of power handling ability.
SDT eases the calculation of the DC resistance and efficiency of a cell or battery pack, independently of its capacity, voltage and internal cell arrangement.
SDT can be thought of as the theoretical time required to a full cell (or battery) through a short circuit.
Characterization
SDT may be calculated from known parameters of the battery or cells within it, or empirically.
From specifications
SDT can be calculated knowing the cell's or battery's capacity, DC resistance and nominal voltage:
<math>STD = capacity * resistance / voltage </math>
Graphically
SDT can be calculated knowing the cell's or battery's nominal voltage. and having the voltage vs SOC curves at various discharge levels:
<math>STD = </math><VAR>Δ</VAR><math> voltage / </math><VAR>Δ</VAR><math> specific_current / voltage </math>
Where Δ voltage is the change in voltage between any two curves, and Δ specific_current is the change in specific current between those same two curves.
Empirically
SDT can be calculated by measuring the cell's or battery's capacity, DC resistance and nominal voltage:
<math>Short Discharge Time = capacity * resistance / voltage </math>
Usage
Knowing the STD of a cell technology makes it possible to easily calculate resistance and efficiency of the cell or of battery using that cell, regardless of its size.
Resistance calculation
The DC resistance of a cell or battery can be calculated from the STD.
Given the battery voltage and capacity:
<math>resistance = STD * voltage / capacity </math>
Or, given the voltage and energy:
<math>resistance = STD * (voltage )^2 / energy </math>
Or, given the energy and capacity:
<math>resistance = STD * energy / (capacity )^2</math>
Efficiency calculation
The efficiency of a cell or battery can be calculated from the STD:
<math>efficiency [%] = 100 * (1 - (STD / ActualDischargeTime ))</math>

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