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Battery knowledge · High-voltage and functional safety

Pre-charge circuit

A resistor and small contactor that charge the inverter’s capacitors slowly before the main contactor closes. Without it the inrush into empty capacitors can reach thousands of amperes and weld the main contactor shut.

Example

Capacitor charge and energy

At 5 V: 25 C and 62.5 J.

Ideal constant capacitance; leakage, series resistance and voltage rating excluded.

Explore the graph

Charge rises linearly with voltage; energy rises with voltage squared.

Stored charge
Stored chargeVoltage (V) versus Charge (C). Q = CV. Interpretation follows the graphs.006.251.2512.52.518.83.75255Voltage (V)Charge (C)
Q = CV
Stored energy
Stored energyVoltage (V) versus Energy (J). E = ½CV². Interpretation follows the graphs.0015.61.2531.32.546.93.7562.55Voltage (V)Energy (J)
E = ½CV²

At 5 V: 25 C and 62.5 J.

Q = CV; E = ½CV²

Illustrative model. Ideal constant capacitance; leakage, series resistance and voltage rating excluded.

Use in Lemonergy

Relate protection to faults, detection and response.

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. ISO 26262-1:2018 — Road vehicles — Functional safety — Part 1: Vocabulary

    International Organization for Standardization · 2018

    Topic background · Scope and terminology of automotive electrical/electronic functional safety. The catalogue is not the full standard.

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