Question of the week: Can an MHEV travel on electric power?

David Ross, Editor
Fri, 15 Nov 2024

Dear Honest John,

"I am looking at a hybrid but I am concerned about the electric range. Some called mild hybrids have a small range. I am interested in the Honda Jazz hybrid but then I read it has only 0.85kWh battery. Is this correct? If so it seems like a mild hybrid.

Are there any engine-driven hybrids which also have a plug-in facility? If not, is there any reason not to have this? I would have thought it must only entail a socket plus some more control gear.

I would be very interested in such a car which has about 100 miles electric range, plus I can charge it up at night for shorter journeys. Such cars could be fitted with much smaller fuel tanks."

- AM

Dear AM,

It is important to clarify how different types of hybrids operate. A mild hybrid - or MHEV - cannot travel on electric power alone.

Instead an electric motor works to provide a small amount of extra power to the engine when needed, usually in order to assist with efficient acceleration.

MHEVs often use a generator in place of a starter motor to make the stop/start system work more smoothly. Power is stored in a small lithium ion battery which is recharged during braking.

The Honda Jazz Hybrid is a full hybrid but operates differently to the majority of full hybrids, as it does have a small 0.86kWh battery which means it can only travel on electric power for very short periods.

However, when the battery is depleted it uses the engine as a generator to power the electric motors, only driving the wheels directly at higher speeds. Honda says this is a more efficient arrangement.

Most full hybrids have larger batteries which means more range on electric power only, but when required the engine kicks in and drives the wheels directly, either on its own or in combination with the electric motors.

Plug-in hybrids offer the additional facility to charge the vehicle from an electric charging point, which means it is possible to spend a greater percentage of your driving time on electric power alone as you are not relying on regenerative braking or the engine to recharge the battery.

Some buyers see this as a better option than a conventional hybrid, especially if you need to do frequent short journeys which can be completed on electric power and you have access to a home charger. As an example, the Audi A3 TFSI e and Volkswagen Golf eHybrid PHEVs have a claimed EV range of 88 miles.

Ask HJ

I'm looking to replace my Hyundai Ioniq with another PHEV, what should I choose?

I currently have a Hyundai Ioniq PHEV that I plan to replace this August with a new PHEV. The Ioniq PHEV is no longer produced - what would you recommend about the same size?

PHEVs have been a popular choice for customers looking to move into electrified vehicles, but manufacturers are moving towards full EVs which means the number of PHEVs available is diminishing. One option is the Volkswagen Golf e-Hybrid. It is a bit more expensive than your Ioniq, but this is partly offset by the better performance, driving experience and higher-quality cabin. Alternatively you could go for the MG HS, which is a little larger than your Ioniq but offers excellent value for money.

Answered by David Ross

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