You might have heard of ‘Range Extender’ hybrids and wondered why they’re still not prevalent in Europe. In theory, they propose a near-compromise-free combination of EV-like electric range with a small ICE engine that can keep the batteries topped up – but, as MG’s boss of R&D has just explained, there’s a problem.
Advertisement – Article continues below
Qiu Jie told Auto Express: “It’s very difficult to make range extenders Euro 7 compliant. A range extender won’t pass Euro 7 [emissions regulations], but a PHEV will.” If this initially seems confusing, it has to do with how range-extenders work – and a quirk of the Euro 7 testing procedure that uncovers a gap in this type of powertrain’s eco-credientials.
Firstly, to be considered a ‘range extender’ hybrid, the car must work largely as an EV, with a correspondingly large battery pack. In certain Chinese-market models, this often sits between 40kWh and 80kWh. When the battery is depleted, it calls on a small petrol engine to generate power for the batteries in order to drive the wheels. There is no physical connection between wheels and petrol motor, but it’s at this operating phase that the issue arises.
Qui Jie explained that with a low state of charge in the battery, a petrol engine has to work very hard to ensure that it’s producing more power than the electric motors are calling for. Although some owners won’t often find themselves in this situation, the assessment for Euro 7 regulations includes emissions testing for hybrids with a low state of charge, and it’s in this operating phase that it could be very hard to satisfy the Euro 7 rules.
Many range-extenders have limited emission-control devices due to the cost of implementing a large battery pack, electric motors and a combustion engine plus all its ancillaries.
Plug-in hybrids are different, because their combustion engines generally play a more active role in the car’s general running cycle, and therefore come with more emissions-related tech. Plus, with the engine being directly connected to the car’s wheels, PHEVs are also generally more efficient in their pure petrol modes, in effect acting as an overweight full-hybrid car.
Don’t miss out! See more of Auto Express in your Google Top Stories. Click here…
