NX450 performance when the EV battery is exhausted

[aji1]

Interested in your experiences once the drivetrain Battery is out of charge and the 450 is relying on the petrol engine.

Does performance (acceleration/overtaking) really suffer and the car turn into an overheavy underpowered SUV?

Does MPG get really bad?

Does the car harvest much from braking and over-run and charge the Battery up again?

Thanks!

[Tickedon]

The car will charge up a bit with lots of braking going downhill (there’s a big hill near me) - I might get an extra mile or so from a really long stretch. But there’s no meaningful recharge of EV-only driving miles.

I don’t find it problematic without any Battery charge. A recent trip, no EV miles, 70 minutes long and a mixture of urban, A roads, and motorway the car showed 50.7mpg at the end of the journey for that trip . Shorter trips are more usually 40-45 mpg pottering around where I live when ai don’t have any charge. I would say it’s very competitive compared to my previous diesel saloon (given diesel is slightly more expensive) - note I tend to use premium fuels not basic unleaded / diesel just in case it matters.

I’m not a slow driver and haven’t noticed any loss of power once EV miles used up, as you still have the 30% or so of Battery kept for the normal hybrid driving. I’ve never managed to exhaust that part of the Battery (as it does recharge as you brake, drive, etc.), car seems to do a very good job of balancing petrol engine and what’s left in the Battery for normal hybrid driving.

[stepppy]

You will find that unlike a lot of other plug in Hybrids, the Toyota/Lexus system still retains a portion of the traction Battery for hybrid driving as @Tickedon mentions.  This effectively makes it pretty much as efficient as the standard 350h.

Therefore you are not lugging around a useless empty Battery, it is in fact still fully functional as the standard non plug in version.

[Hayzee]

Al (above) is completely right. The NX HEV has a hybrid (traction) Battery of just 1.6 kWh whereas the PHEV Battery is 18.1 kWh of which about 5.4 kWh (30%) is reserved for HEV mode. So it has 3.8 kWh more hybrid Battery than the HEV for non EV driving.. This allows the PHEV to maintain all it's 302 HP regardless of having zero EV miles available, so performance is never compromised. MPG would also not be affected, except by your driving habits.

[Harrier Man]

No noticeable drop in performance, as explained by Colin. Under normal conditions the 450 is continually maintaining the Battery at around 30% on braking or the over-run but it doesn't get much above this as it uses the Battery often. This can be seen in the Trips section of the app for a particular journey where you can see frequent changes between ICE and EV (once the engine is warm) even after the Battery has hit minimum for full EV use. In these conditions, the mpg is okay because the car is behaving as a mild hybrid as Stephen mentions.

The 450 does have a mode where you can force the ICE to charge the Battery (up to 80% of a full charge) that does impact on mpg and noise levels. For these reasons, I don't use this mode on A roads but I do use it on motorways where I can maintain a fairly steady speed. Passengers don't notice the change in noise levels and it's not a big hit on the mpg in these conditions.

[Scotlex]

As said before, the Battery is never out of charge. 

[Scotlex]

I often use the engine to charge the Battery and then just plug in at home to top the Battery up.

Performance is still fine 😃

[Serguei]

I am not sure what is the point of using the engine to charge the batteries. It only increases fuel consumption without giving anything else in return. What am I missing?

I plug the car and do all local trips on electrics, but if I have to drive further than the Battery can last I just let the car to take care about it, so that it just keeps the charge at around 30%.

 

[ColinBarber]

10 hours ago, Serguei said:

I am not sure what is the point of using the engine to charge the batteries. It only increases fuel consumption without giving anything else in return. What am I missing?

Only useful if you want to reduce sound or air pollution in an area later on in your journey. Otherwise, as you say, it is pointless and a very inefficient way to recharge the Battery compared to plugging in.

[bgb]

Echo the sentiments of others.  This is something we used to do when driving regularly from Yorkshire to Kent when we had a BMW 330e.  We don't bother with the NX because, a) it still operates efficiently as a "standard" hybrid at 30% charge and b) there is a 'performance' hit when in chg mode, if you need to accelerate to join a motorway or overtake, you will not get much return for your right foot depression other than noise from the e-cvt so you need to be prepared for switching modes.

[Harrier Man]

15 hours ago, Serguei said:

I am not sure what is the point of using the engine to charge the batteries. It only increases fuel consumption without giving anything else in return. What am I missing?

I plug the car and do all local trips on electrics, but if I have to drive further than the battery can last I just let the car to take care about it, so that it just keeps the charge at around 30%.

 

My motivation is that I want to be green and quieter later on in my journey, particularly if the end point is a town or city. There are no motorways this far North in Scotland so a typical scenario for me is the drive from Scotland to Wales. I start in electric until it runs out and then onto the ICE; I switch to use the ICE to charge the Battery on the M74 so that when I get off the M6, I can find my B&B (the insurance for many B&Bs precludes EV charging); two days of running about to local attractions on battery; drive rest of way to Wales using the ICE, charging the Battery again when I'm back on the M6; switch back to EV mode for the Battery to drive through Aberystwyth and to my final destination - where I can charge up using the granny charger for local running around and before setting off for the return journey to Scotland. Hence, very selective use of the ICE to charge the Battery and, in my subjective experience, charging at steady motorway speeds doesn't make a big difference to mpg.

[Scotlex]

16 hours ago, Serguei said:

I am not sure what is the point of using the engine to charge the batteries. It only increases fuel consumption without giving anything else in return. What am I missing?

I plug the car and do all local trips on electrics, but if I have to drive further than the battery can last I just let the car to take care about it, so that it just keeps the charge at around 30%.

 

As an answer, what is the point of buying a car with an expensive 2.5 litre engine and then not using the engine? You would surely be better buying a fully electric car.

I will often drive around the city using fully electric but will then use the hybrid system on the motorway. When I arrive at my destination I will again use fully electric.

[Serguei]

5 hours ago, Scotlex said:

As an answer, what is the point of buying a car with an expensive 2.5 litre engine and then not using the engine?

I did not say I was not using it!.

I use the engine on the trips that are longer than the Battery range. But I don’t use the function of charging the Battery back to higher level, I just continue driving it as a self-charging hybrid when the Battery charge stays around 30%.

This is what plug-in car is for - use electric on short trips and then drive car long distance without having to charge it. 

[Serguei]

6 hours ago, Harrier Man said:

My motivation is that I want to be green and quieter later on in my journey, particularly if the end point is a town or city

I see.

I personally don’t bother. If I go away from home I let it run out of Battery I just use it as a self-charging hybrid until I return home where I have a proper 7kw charger in my driveway.

My specific use-case is ideal for plug-in hybrid - I have a driveway and most of our daily driving is well below the range.

[Saxacat]

I recently did my first long journey in the NX.  I started the journey with the tank full and Battery at 100%; I used HV mode for the whole journey, which was mostly motorway roads and driving to the speed limit. I filled the tank as soon as I arrived, having driven 339 miles, it took 6.6 gals to fill it, the Battery still showed 100%; as the Battery was at 100% at the end of the journey, I'm guessing the fuel figures probably would have been the same if the traction Battery had been exhausted when I started the journey.

[Serguei]

3 hours ago, Saxacat said:

the battery still showed 100%; as the battery was at 100% at the end of the journey, I'm guessing the fuel figures probably would have been the same if the traction battery had been exhausted

I suspect the fuel figures would be better if the traction Battery was exhausted (or at least at a lower level)  

When one drives in HV mode with 100% Battery, where the electricity generated when you go downhill or break is to go?

Also it is not good for the Battery to be at 100% for a long time. The manual actually says that when one is not using the car for some time it is better if the Battery is deprecated (I.e. at 30%). 
 

[Saxacat]

37 minutes ago, Serguei said:

I suspect the fuel figures would be better if the traction battery was exhausted (or at least at a lower level)  

When one drives in HV mode with 100% battery, where the electricity generated when you go downhill or break is to go?

Also it is not good for the battery to be at 100% for a long time. The manual actually says that when one is not using the car for some time it is better if the battery is deprecated (I.e. at 30%). 
 

It was using the traction Battery on the journey, the car switched into EV mode when circumstances dictated, as it's designed to do in HV mode; I would guess that the regenerative energy would then top up the energy used during these periods.

This was my first long journey in a PHEV, and I wanted to see how the car's systems worked on such a journey; the Battery was at 100% for the journey, once I came off the motorway at my destination, I switched from HV to EV.

[Scotlex]

It is interesting to see how others use their NX.

It is quite a versatile car 😀

[Pm4]

I started to use ev until it ran out, now on long journeys I switch manually to ev at speeds below around 50mph and back to hv above that, I  think it's more efficient, but not sure? 

[Harrier Man]

It's  true that the Battery will deplete at a faster rate at higher speeds than lower speeds but it is also true that you will use more fuel at higher speeds than lower speeds. I think other factors would come into play. At a steady 50mph, the petrol engine is pretty efficient but not so much if there is a lot of acceleration and deceleration that gives rise to an average of 50mph (if this is the case, the EV might be more efficient).  There are so many variables, that a fixed rule is probably better considered as a guide.