To what extent do Hybrid buses use their electric capabilities?

Lots of my local routes and others I've used within London are operated by a mix of hybrid and regular double deck buses (according to the large space at the back where I'm guessing the battery goes and the sign on the side of the bus). No matter the time of day, the hybrid variants rarely appear to cut out their engines and run on battery mode (I believe hybrid buses only ever do upon initial acceleration then the diesel engine kicks in at a certain speed).
In addition, new single decker buses that have 'hybrid' written on the side in my local area appear to never actually run in electric and only some drivers appear to enable the engine cut out when at a stop or red light (if they can even control that)

I'm just wondering if anyone has any insight to this, do garages not bother to charge up batteries? Are my experiences unique? I will try to edit in makes of the buses in question although I don't know much about buses so please excuse my ignorance. Many thanks.

You get two types of Hybrids (within buses)... I'm sure someone will elaborate in more technical detail, however a quick summary!

• Series Hybrid (Example: Enviro400H)... Bus is propelled entirely by an electric motor, a smaller than standard diesel engine acts as a generator to power the motor, because the engine is smaller you use less fuel.
• Parallel Hybrid Example: Volvo B5LH)... The electric motor and diesel engine work in parallel (hence the name) to propel the vehicle, because of this the engine is under less pressure/strain so uses less fuel and thus pollutes less than a standard diesel bus, the engine also typically tends to be smaller than normal.

While some Hybrid buses (such as the B5LH) have the option to drive in full electric mode the range tends to be fairly limited and once you pass a set speed the engine will kick in anyway.

The Enviro400H on the other hand cannot be driven in 100% electric mode, however ADL have recently launched the new Enviro400ER which has the ability to drive in fully electric mode for a limited period of time, the area of the route that it drives in electric mode can also be geo-fenced in so that the bus is in electric mode along the most polluted areas of a route.

Ethano92 said:

In addition, new single decker buses that have 'hybrid' written on the side in my local area appear to never actually run in electric and only some drivers appear to enable the engine cut out when at a stop or red light (if they can even control that)

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It sounds like those buses are fitted with start stop technology.

Ethano92 said:

(I believe hybrid buses only ever do upon initial acceleration then the diesel engine kicks in at a certain speed).

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Those will be the Volvo B5LHs, which after a certain speed (8MPH off the top of my head) the engine kicks in.

Jordan Adam said:

You get two types of Hybrids (within buses)... I'm sure someone will elaborate in more technical detail, however a quick summary!

• Series Hybrid (Example: Enviro400H)... Bus is propelled entirely by an electric motor, a smaller than standard diesel engine acts as a generator to power the motor, because the engine is smaller you use less fuel.
• Parallel Hybrid Example: Volvo B5LH)... The electric motor and diesel engine work in parallel (hence the name) to propel the vehicle, because of this the engine is under less pressure/strain so uses less fuel and thus pollutes less than a standard diesel bus, the engine also typically tends to be smaller than normal.

While some Hybrid buses (such as the B5LH) have the option to drive in full electric mode the range tends to be fairly limited and once you pass a set speed the engine will kick in anyway.

The Enviro400H on the other hand cannot be driven in 100% electric mode, however ADL have recently launched the new Enviro400ER which has the ability to drive in fully electric mode for a limited period of time, the area of the route that it drives in electric mode can also be geo-fenced in so that the bus is in electric mode along the most polluted areas of a route.



It sounds like those buses are fitted with start stop technology.



Those will be the Volvo B5LHs, which after a certain speed (8MPH off the top of my head) the engine kicks in.

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I didn't realise there were different modes of hybrid so thank you, that already explains a lot. I suppose on a parallel hybrid, as a passenger you wouldn't notice the difference from a regular bus which probably explains a lot of my confusion.

As for the Volvo B5LH, which is the bus I had in mind from a quick Google search, is it's only hybrid capability to run on electric up until ~8mph or does it also have other technologies as from my own frequent anecdotal experience, this cut out/electric running very often doesn't actually happen.

Why can't the ADL series hybrid be driven in electric mode? I thought a series hybrid drivetrain would be more suited to that.

Bornin1980s said:

Why can't the ADL series hybrid be driven in electric mode? I thought a series hybrid drivetrain would be more suited to that.

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series-hybrid systems can drive for a little distance in all-electric mode, but the BAE HybriDrive system used in Enviros only permits that during setoff and just before the bus stops. The ability of the system to do that depends on the electric power available to the electric motor, and this factor will also determine the length of time during which only electric traction will be used.