Thermal characterisation

Example

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Use in Lemonergy

Record specimen, state, instrument, temperature and timing.

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Accelerating rate calorimetry

A test in which a cell sits in an adiabatic chamber that follows its temperature, so any self-heating is not lost to the surroundings. It measures the onset temperature, the self-heating rate and the temperature at which runaway becomes unstoppable.

Entropy coefficient

The change of open-circuit voltage with temperature, dE/dT, usually a fraction of a millivolt per kelvin and varying with state of charge. It sets the reversible heat a cell absorbs or releases, which can be a large share of total heat at low current.

Heat generation

The heat a cell produces in operation: an irreversible part equal to current times overpotential, and a reversible part from the entropy change, I·T·dE/dT. The Bernardi equation sums them and feeds every thermal model.

Thermal model

A model of cell temperature: at its simplest one thermal mass with heat generation inside and convection outside, at its most detailed a 3D simulation of the pack. Temperature feeds back into every rate, so electrical and thermal models are usually solved together.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

1. Battery Test Manual For Electric Vehicles, Revision 3

   Jon P. Christopherson · Idaho National Laboratory · 2015

   Topic background · Performance characterization, pulse resistance/power, life testing and reference performance tests; historical 2015 edition.