Battery knowledge · Testing methods

Power spectral density

The way a random vibration profile is specified: acceleration intensity per unit frequency, in g²/Hz, across a band such as 5–200 Hz. The square root of the area under the curve gives the overall level in g rms. SAE J2380 and ISO 12405 use PSD profiles to stand for road vibration, whereas UN 38.3 uses a sine sweep.

Abbreviation
PSD
Also called
PSD vibration profile, random vibration, acceleration spectral density, ASD
Unit
g²/Hz
Relationship
g_rms = √(∫ PSD(f) df)

Example

Integrate a flat vibration band

An illustrative one-sided acceleration PSD of 0.01 g²/Hz from 10 to 110 Hz has area 1 g² and therefore 1 g RMS. A peak PSD value alone does not determine RMS without the bandwidth.

Explore the graph

A flat illustrative vibration band makes the integral easy to inspect.

Authored one-sided acceleration PSD
Authored one-sided acceleration PSDFrequency (Hz) versus PSD (g²/Hz). 20–200 Hz flat band. Interpretation follows the graphs.000.00362.50.0061250.0091880.012250Frequency (Hz)PSD (g²/Hz)
20–200 Hz flat band

Band width is 180 Hz. Variance = 1.8 g²; RMS acceleration = 1.342 g.

g_rms = √∫ PSD(f) df

Illustrative model. One-sided rectangular teaching spectrum. No resonances, random time history or standard-specific profile is generated.

Use in Lemonergy

Record specimen, state, instrument, temperature and timing.

This is a reference concept. No executable Lemonergy block has been verified for this term.

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.