GREEN SPECIAL: What's the difference between BEV, PHEV and hybrid?
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This has certainly been the year of the EV in New Zealand: partly because the move towards electric cars is a global phenomenon, but especially because the Government has introduced a Clean Car Discount that gives rebates of $8625 to buyers of a brand-new Battery Electric Vehicle (BEV) and $5750 for a Plug-in Hybrid Electric Vehicle (PHEV). Nothing at this stage if you purchase a hybrid; although that will change for all low-emissions vehicles from April next year once the expanded Clean Car “feebate” system kicks off.
All of this has put the spotlight on what the differences are between these technologies. Why do you get more back for a BEV than a PHEV and nothing at all for a hybrid? How do you know which is which?
Let’s start at the top. “BEV” is potentially a bit confusing because all electric cars have batteries of some kind. All cars have batteries of some kind, actually.
But a BEV is powered only by the battery, which uses an electric motor (or motors in some cases) to drive the wheels. There is no petrol or diesel engine, which means the only way you can “fuel” it is to plug in and charge up. A BEV is arguably the most “pure” of EVs; if you charge it using only sustainably produced electricity, which is certainly possible in NZ, it’s the cleanest kind of car.
You also plug in a PHEV, but it has a much smaller battery and can only drive for shorter distances on pure-electric power: 30-80km is typical, depending on the model (the BMW X5 xDrive45e can do 77km, for example). The key difference with a PHEV is that when the battery runs out, there’s also a petrol or diesel Internal Combustion Engine (ICE) that enables it to run as a hybrid: the ICE and electric powertrains work together and of course the battery can be charged either by the ICE, or through energy recovered during braking and deceleration (what is sometimes called “regeneration”).
To illustrate, consider two MINI products: the Electric hatch (below left) and the Countryman SUV PHEV (below right). As the names suggest, the former is a BEV and the latter a PHEV.
The MINI Electric has a 28.9kWh battery (the battery is like the fuel tank of a BEV) and a maximum range of 233km; you can charge to 80 per cent in 36 minutes on a public DC fast charger.
The Countryman PHEV has a 9.6kWh battery that’s good for 55km – not much compared to a BEV, but plenty for most daily commutes. And when that range is used up, it turns into a hybrid with a 1.5-litre turbo-petrol engine, meaning you can drive as much as you want and simply fill with fuel like you would in an ICE vehicle.
The key thing to remember is that for a vehicle to be an EV – at least according to the NZ Government – it must be able to recharge from an external power source. It must have a plug, in other words.
That’s also the key difference between EVs (which includes both BEVs and PHEVs) and hybrids, which have additional battery capacity and “electrification” like a PHEV, but cannot be recharged from the mains. They are sometimes (confusingly) called Hybrid Electric Vehicles (HEVs) – even though they are not technically EVs!
The Toyota RAV4 is probably the hybrid most Kiwis are familiar with: it has a 2.5-litre petrol engine and a small battery that work together. Even with a full battery the RAV4 hybrid can only run on electric power alone for a kilometre or two, but rapid regeneration means it can spend much of its time in city driving using very little fossil fuel, because every time you lift off or brake, charge goes into the battery.
Many carmakers are also now utilising “mild hybrid” (MHEV) technology, with high-voltage electrical systems that use regenerated power to help with high-demand electrical systems – anything from engine starting to adaptive suspension. Because the engine is not working as hard to supply that power, it’s free to do what it does best: propel the car. It can sometimes even get a little boost from the hybrid system. Mild hybrids can’t generally drive on battery power alone, so they really don’t feel too different from a conventional ICE car.