Every month, more and more electric vehicles (EVs) are being imported into New Zealand, but many of our motorists are still unfamiliar with the battery technology used to power them. The electric motor in these vehicles are powered by a high voltage, generally, lithium ion battery pack.

You can think of the high voltage battery pack in an EV as a new kind of fuel tank, as it effectively stores the fuel used to propel the vehicle.  If you’re considering buying an EV, it’s important to understand the three main aspects of this ‘fuel tank’ – its capacity, charging and range.  

Capacity                                          

An EV’s battery is rated in kilowatts per hour (kWh) - a measurement of electricity for the amount of energy expended in 60 minutes by one kilowatt of power. So the more kWh the battery capacity has, the longer the vehicle range.

For example, a 2019 Nissan Leaf has 40kWh and an average range of 270km, whereas a 2018 Hyundai Kona EV has a range of around 400km thanks to its 64kWh battery. These range recommendations are of a new vehicle and subject to driving conditions and driver behaviour.

This shouldn’t be confused with the power rating of the actual electric motor which is measured in kilowatts (kW). The power of the motor is what produces the impressive torque demonstrated by EVs.

Charging

The life and performance of a high voltage EV battery pack is very reliant on the charging pattern it is exposed to. There are common precautionary measures that can be taken to maintain the state of health (SOH) of your battery and its longevity. See the user manual of your EV for correct charging regime. 

There are currently 3 main methods for charging:

1) Home (via an In-Cable Control Box (ICCB) charging cable)

This is designed to connect to a standard three-pin wall socket, but it’s a slow overnight charging method and will fully recharge a used Nissan Leaf in 6-8 hours or a Kona in around 43 hours. The power supply from this cable is typically 10amp/2.4kW.

 2) Home (via a Fast Charge Wall Box)

This is an optional wall box for your household and improves charge times by utilising a 16-32amp 3.7-22kW power supply. It can significantly reduce EV charging time at home but currently costs a few thousand dollars to purchase and install.  

3) Public Rapid Charging Stations

This is the fastest way to charge an EV, and can take up to 75 minutes to charge a large capacity EV from 0% to 80%, typically utilising 25-50kW DC charging.

4) Mobile EV  Charger – Service provided by AA Battery Service

This is a mobile EV charging service provided by AA Battery Service Ltd. This service is currently available in Wellington CBD only. AA Battery Service mobile EV charger will come to you when you in, rare circumstances, do run out of juice in your EV high voltage battery pack. A 15 – 20mins of charge at 15amp/3.7kW will put in enough charge to get you going for another 10 -12km helping you to get to the nearest charging station or home if it is in the range. This service is free of charge to all AA Members.

Range

Battery range is dependent of environmental factors and load, so unlike petrol in your tank, you are draining the high voltage EV battery by having anything electrical on in the car. Thankfully though, brake regeneration systems can put enough charge back into the battery to counter this and boost your range as you drive. During winter and extreme cold weather your EV battery can lose up to 12% of range as extreme weather affects battery performance.

Two common terms you might hear when shopping for used EVs are ‘state of charge’ and ‘state of health’.

State of charge (SOC) is defined as the available capacity (in Ah) and expressed as a percentage of its rated capacity. State of health (SOH) represents a measure of the battery’s ability to store and deliver electrical energy, compared to a new battery.

Like with a smartphone, over time an aging EV battery can reduce in ability to store charge (SOH) while the demand from the motor’s power remain the same.  When acquiring a second hand EV it is important to consider the state of health of the battery. It is not necessary that a battery at 100% state of charge (SOC) will deliver 100% of the recommended range. State of health (SOH) of EV batteries deteriorate due to age and the charging regime and hence resulting in reduced range.

The future

The next generation of EVs due to enter the New Zealand market over the next 12-months will meet the demand for increased capacity DC fast charging systems in excess of 150kW. This can charge a high capacity EV like the new Audi E-Tron to 80% in just 30 minutes.

And it doesn’t just stop there; the requirement for a quick high-capacity “dump” of electricity will also increase - it’s reported that the new Porsche Taycan will have the ability to accept an impressive 350kW.

Like any new vehicle, EVs also have a warranty which covers the battery, typically 5-8 years or a set distance (i.e. 100,000km). It’s still early days and we’re yet to see what an “expected” EV battery life looks like.

Some EV batteries are recyclable and they’re able to be repurposed. For instance, An EV battery no longer able to power a car could still store enough energy for use with a home. A high voltage EV battery pack should be handled by qualified personnel only.

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