HV Definitions and Glossary

The HV Definitions & Glossary is an A to Z extension to our website that just gives you an alternative way of finding information.

Battery Disconnect Unit – contains the contactorsfuses, pre-charge circuit and current sensors. This unit sits inside/on top of the battery pack and has all of the components for monitoring, activating, and deactivating the high-voltage battery system.


Busbars are the main electrical connections between cells, modules and connect all of the HV system to the outlet connector. Normally made from copper or aluminium.

Clearance – the line-of-sight distance between two conductors through the air.

Charge Voltage – voltage that the battery is charged to when charged to full capacity.

Contactor – a switch that can be operated by the control system. They are essentially a relay.

Creepage – the distance between two conductors on the surfaces of the parts or along the surface of the insulating material.

Current Sensor – can include resistive or magnetic elements based on their structure. We use these elements for sensing the current to be measured.

Cut-off Voltage – the minimum allowable cell voltage defines this lower voltage limit.

Fuse – device that protects electrical circuits against undesired high currents. We can use passive fuses and pyro fuses in battery design.

HV – abbreviation of High Voltage and in automotive world this means above 60V DC.

HVIL – Hazardous Voltage Interlock Loop.

Isolation Resistance of a Pack – for the complete HV system to ground with the contactors closed should be >500Ω/V and hence for a battery pack its resistance target must be specified by the HV System designer, typically >1,500kΩ.

LV – abbreviation of Low Voltage and in automotive world this means below 60V DC.

Nominal Voltage – reference voltage of the battery at 50% state of charge and at the defined discharge rate.

Pre-Charge Resistor – when the battery pack contactors are closed onto a motor and inverter there will be an inrush of current into the inverter capacitor. This very high current is at a minimum likely to age the contactors, it could permanently damage the contactors.

Pyro Fuse – a fuse that can be blown by a signal.