Hybrid Battery Question

[npnicholson]

I've had a 2015 Auris Hybrid Tourer for a few months now and I've never seen the Battery achieve full charge. It always has at least one bar which isn't green on the display. I can understand why it doesn't get charged while I'm driving around town, but on a decent motorway run I thought it would?

A related question is how long should it be able to drive on Battery (at walking speed) from an almost full charge? The other day I arrived at my destination with the Battery showing one bar short of full charge, but it only managed a few minutes driving around a multi-story car park before the battery was almost discharged and the petrol engine cut in.

[Gerg]

Hi,

It's not intuitive, but the car tries to keep the top two bars of 'charge' empty, so that if the car needs somewhere to put energy from regenerative braking, then it can go into that spare capacity, otherwise that energy would be wasted.  The car will never normally charge those top two bars when driving at a steady speed on the flat.

In fact, the Battery SOC (State Of Charge) indicated on the meter is not the real range of Battery charge.  The car is only using a part of the total charge range, by doing this an improvement in long-term Battery life is achieved.

A figure I have read quoted for battery-only range is 1.25 miles, but that would be on the flat.  Hills or inclines will deplete the battery much faster.

This diagram (actually from a Prius, but still basically holds true for the Auris) may help explain some of this. 

[npnicholson]

13 minutes ago, Gerg said:

Hi,

It's not intuitive, but the car tries to keep the top two bars of 'charge' empty, so that if the car needs somewhere to put energy from regenerative braking, then it can go into that spare capacity, otherwise that energy would be wasted.  The car will never normally charge those top two bars when driving at a steady speed on the flat.

In fact, the battery SOC (State Of Charge) indicated on the meter is not the real range of battery charge.  The car is only using a part of the total charge range, by doing this an improvement in long-term battery life is achieved.

A figure I have read quoted for battery-only range is 1.25 miles, but that would be on the flat.  Hills or inclines will deplete the battery much faster.

This diagram (actually from a Prius, but still basically holds true for the Auris) may help explain some of this. 

Many thanks for this comprehensive answer. I thought it must be deliberate that the Battery doesn't fully charge but just wanted to make sure. I think the battery-only range is disappointing. It seems a bit pointless to have a battery-only driving mode, which in practice you usually can't use because there's not enough charge.

[Gerg]

You are welcome!

There are plenty of owners that would agree with you, especially your point about the 'EV' Battery only button.

The way the car has ended up, to an extent, makes more sense when the mechanics and electronics are 'laid bare'.  As you perhaps already know, the transmission and associated parts in the HSD are quite different from a normal car, and the way the car drives (i.e. basically like a normal automatic) is quite a testament to the ingenuity of the engineers in concealing what's really going on under the bonnet.  It's quite novel how they have managed to design a car missing a torque converter/clutch and most of the gearbox.  And no alternator, starter motor or drive belts.  Some may think they left out too much sound-proofing (actually, that's probably just me), but the refinement is excellent, apart from the 'mooing' sound when you press-on.

This link is quite old now (it is about the Prius gen 1 and 2), but apart from some of the detail, it is the same as your Auris' engine /transmission.  I'd suggest going to the section 'Understanding Your Prius', then perhaps 'Powertrain Components'.  He's obviously quite passionate about his car!

http://prius.ecrostech.com/original/PriusFrames.htm

In a hybrid, the Battery capacity  is massively hampered by 'packaging' considerations (e.g. keeping a decent size boot space).  And a bigger Battery costs more, of course.  I suppose Toyota have judged the battery size to be big enough to make a worthwhile difference to fuel economy and town-driving refinement, without compromising too much else.  Certainly in your version (Auris Mk2), the hybrid bits are hidden away with enough success to make it look exactly the same as any other Auris, which is some achievement.

Toyota must acknowledge there is room for improvement and development; the next generation of the Hybrid powertrain (in the latest Prius) *is* better!