AA Car Care: Electric Vehicle (EV) batteries explained
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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.
You can think of an EV battery 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.
An EV’s battery is rated in kilowatt hours (kWh) - an electrical measurement of the amount of energy transferred in 60 minutes by a power flow of one kilowatt. 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.
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.
There are currently three main methods for charging:
Home (via an In-Cable Control Box, ICCB)
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 new Hyundai Kona in around 43 hours. The power supply from this cable is typically 10amp/2.4kW.
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 can sometimes cost over $3000 to purchase and install.
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 0-80 per cent, typically utilising 25-50kW DC charging.
Battery range is dependent on environmental factors and load, so unlike petrol in your tank, you are draining the 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.
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 with a new battery.
As 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 remains the same. This means that a full battery charge won’t last as long, resulting in reduced range.
The next generation of EVs due to enter the NZ market over the next 12 months are meeting the demand for increased capacity DC fast charging systems in excess of 150kW, which can charge a high capacity EV like the Audi e-Tron to 80 per cent in just 30 minutes.
And it doesn’t just stop there; the requirement for a quick high-capacity “dump” of electricity will also increase – the new Porsche Taycan is one car with this capability (up to 270kW, or 100km range in five minutes).
Like any new vehicle, EVs also have a warranty which covers the battery, typically 5-8 years or a set distance (100,000km for example). 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 at home.
How is the AA is helping with the switch to EVs?
The AA recently joined EECA’s Gen Less campaign to show the ongoing action it is taking to live and work in more climate-friendly ways and also provide practical tips, tools and ideas for how its 1.7 million members might do more with less.
The AA is a founding member and sits on the Governance group of the Battery Industry Group (www.big.org.nz).
A couple of years ago, it launched the AA EV Charge Finder, a platform built in collaboration with Waka Kotahi (NZ Transport Agency) and other industry partners, which collects live information from safe and monitored charge points across the country to help drivers plan their journeys.
Also, on 20 July 2020, the AA Battery Service introduced a new mobile EV charger to its AA Roadservice fleet in Wellington, meaning if you do run out of juice the AA will be able to help you get back on the road.