How to

How to disconnect the high voltage power in an EV

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Performing any maintenance on a high-voltage system can be extremely hazardous, so it’s important to have the right training and follow the proper safety procedures.

Follow along with our Delphi expert who will tell you:

The correct steps to disconnect the power
The equipment you need
Essential safety advice

Batteries How to Technicians 2 min read

Do I need training before I perform any maintenance or disconnect a vehicle’s high-voltage power?

Yes, absolutely. Do not attempt this procedure without the right training as it could result in personal injury or death.

Why is it hazardous?

The Nissan Leaf, like other electric or hybrid vehicles, uses a high-voltage battery system. ‘High voltage’ is generally considered anything over 50 volts. Today’s electric vehicles may produce voltages up to 900 volts, whereas a conventional vehicle may only operate between 12 and 16 volts.

What do I need to safely disconnect the high voltage power?

First and foremost, you need a good understanding of the vehicle manufacturer’s high-voltage system shutdown procedure for the specific vehicle that you’re working on – as this can vary not only from manufacturer to manufacturer, but also from model to model. You can find this in the vehicle’s manual and documentation.

It’s also essential to wear a pair of insulating gloves made from rubber or synthetic rubber, rated to 1000 volts AC or more which are in good condition and haven’t expired their use by date.

What are important watch-outs?

The high-voltage power system must be properly shut down according to the manufacturer’s guidelines before you can disconnect.

Even when the system has been shut down, it’s best to always assume that the circuit is live to be as careful as possible.

Make sure to tell any other technician in the workshop that you’re working with high-voltage circuitry, and prevent any possible reconnection by securely locking away components needed.

It’s a good idea to also remove any jewellery, especially on your hands like rings or watches, or any loose change or anything metallic in your pockets that may fall out.

What are the steps for disconnecting high-voltage power in an EV vehicle?

• Read the vehicle manufacturer’s official guidance and procedure.

• Turn off the vehicle, remove the key and wait for the prescribed amount of time to allow the system’s capacitors to discharge.

• Put on your protective clothing.

• Remove the service disconnect as prescribed in the manufactures guidance.

• Using your digital multimeter, check there is no voltage present as the prescribed test points.

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