I Can Explain Everything. Actually, No, I Can’t.

Achieving the impossible?

Image: Mag-Cars

In the recent series on the Nissan Qashqai, I mentioned that the latest generation will have a third powertrain option that is so left-field it deserves its own chapter. We are told that the e-POWER version will arrive sometime in 2022 and that nothing comparable has previously been offered in a mass-produced vehicle sold in Europe. What makes it unique is that the powertrain has true petrol-electric drive, a series hybrid system with no mechanical gearbox and electric-only traction. The internal combustion engine drives a generator which charges a buffer battery. This in turn delivers power to the electric traction motor.

Image: Nissan Europe

Nissan’s own presentation video explains the principles and components, with some impressive graphics. In Europe at least, no manufacturer provides a powertrain directly comparable, but some numbers help to indicate how it compares with Nissan’s own conventional hybrid and battery electric vehicles:

IC engine power:  155bhp, which is  just 1 bhp less than the more powerful of the Qashqai mild-hybrid options.

Electric traction motor: 188bhp. That’s your limit, as the IC and electric motors cannot operate to deliver traction together. For comparison, the Nissan Leaf BEV offers the options of 148bhp and 214bhp traction motors.

CO2 emissions and WLTP fuel consumption: The mild-hybrid 2WD Qashqais’ figures vary surprisingly little across the board, whether 138bhp or 156bhp, manual or automatic, the numbers are 143g/km CO2 and 44 or 45 mpg (combined). The preliminary(1) e-POWER figures are 122g/km CO2 and 44.4 mpg (combined).

The Qashqai’s traction battery capacity is just 2kW, one twentieth of the lower capacity Leaf options. It is effectively a buffer, allowing only 2-3km of autonomous running. There is no prospect of plug-in hybrid operation, which would require a minimum of about ten times the battery capacity. Nissan states that the powertrain will continue to operate if the battery is fully discharged, although it is not clear how much the performance is impaired in this situation.

Image: Nissan Europe

Notwithstanding the limited battery capacity, the outcome is a powertrain which replicates the experience of driving an EV: constant torque flow, stepless power delivery, the option of one pedal operation. Everything is there, but for the eerie silence. There are no range anxiety or charging issues, as the only available energy input is fossil fuel from a roadside pump. The downside is that the readily available fossil fuel is heavily taxed, the internal combustion engine burning it produces tailpipe emissions for most of the time the vehicle is running, and the ‘sustainability’ figures will not attract tax benefits or state purchase subsidies.

Image: Nissan

For Nissan, this is not untried technology. The e-POWER system was introduced as an option for 2017 Note and 2018 Serena models in Japan, with 70% and 50% take-up respectively . The 2020 Kicks also offers the e-POWER option, as does the Chinese market Sylphy. The Asian-market forerunners  to the Qashqai e-POWER use the Alliance’s HR12DE engine, a naturally aspirated 1.2 litre triple. All of this has come to pass almost unnoticed beyond Japan, China, and some South-East Asian markets. The West has possibly been too EV-fixated to pay attention but, perhaps rather too late, Nissan has managed to produce, with apparent ease and considerable commercial success, something which was regarded as an engineering impossibility only a decade ago.

As befits the range-topper for the European Qashqai range, Nissan has raised the e-POWER specification with a larger and more powerful three-cylinder engine, the 1.5 litre turbocharged MR15DDT unit. It has been widely stated that this engine is a variable compression ratio type, but this does not appear to be the case. The VC engine is actually the KR15DDT unit, presently exclusive to the 2022 Rogue / X-Trail, used in a non-hybrid configuration with a CVT.

It is likely that the choice of a triple cylinder rather than an in-line four is dictated by the engine compartment width, as the IC engine and e-POWER module are in a transverse end-on configuration. The powertrain is self-contained, occupying the space which would traditionally accommodate a transverse IC engine and end-on transaxle gearbox. The only remote item is the traction battery, about the size of a fuel tank and located beneath the front seats.

The driver-machine interface is textbook EV: Standard, Sport and Eco drive modes and the option of one-pedal control. However Nissan states that the power management system has “a focus on keeping relationship between engine RPM and road speed connected.” The company may be making a virtue of necessity here, as the IC engine will not have much resting time from keeping that small buffer battery topped up. The Nissan press release also states that “Drivers can monitor the energy flow of e-POWER on the 12” TFT meter to check the system state.”(2)

e-POWER is a fascinating piece of systems engineering, but does it make sense in a European context? Many European nations are committed to ending the sale of fossil-fuel powered cars by 2030 and the continent’s major manufacturers are throwing resources and investment at battery-electric vehicles as if their survival depended on it – which it very probably does.

In Japan and South-East Asia the situation is less binary, and consumers seem more willing to try something different. For anyone who has driven a good EV, the idea of a vehicle which replicates the driving experience without range and charging infrastructure anxiety has a great deal of appeal. Maximum torque from the moment the motor is turning and the absence of turbocharger and transmission lag make for a compelling experience. Return to an internal combustion vehicle immediately afterwards and it feels and sounds like a tractor. There will be those who lament losing the sensual and cerebral delights of exploiting an engine’s power band and the sense of control achieved through stirring an oily box of cogs and cones, but they are the steam locomotive footplatemen of our times.

If the driving experience is as good as it ought to be, e-POWER should be a winner, even if the performance and efficiency advantages(3) over the mild hybrids are marginal. There are still uncertainties: performance figures have not been disclosed and, more importantly, neither have prices. The 32bhp maximum output increase will be partly counterbalanced by increased weight but, hopefully, with an extra 70Nm of torque there should be some improvement over the 157bhp mild hybrid.

Costs will matter more than performance to the e-POWER’s success in Europe. Nissan states that the e-POWER option will be sold at “an affordable price point”. Presently, the cheapest automatic Qashqai is the £29,475 158bhp Acenta Premium Xtronic. The highest priced version currently on sale is the 158bhp Tekna+ Xtronic 4WD at £38,855. If entry level for the e-POWER option rises too much over £30K, Nissan will be coming close to the prices of rival manufacturers’ plug-in hybrids, which offer fiscal and functional advantages not provided by the e-POWER system.

A GM enigma:  Voltec and e-POWER compared

While they may not seem directly comparable, there is an interesting parallel between Nissan’s e-POWER vehicles and GM’s 2011 Volt / Ampera drivetrain.

Chevrolet Volt Image: Wired

Envisioned as Bob Lutz’s ‘Prius fighter’, the GM Volt / Ampera took a different approach to Toyota’s parallel / series hybrid technology. Described as a ‘range-extended battery-electric vehicle’, the Voltec system was originally intended to have electric drive only, just like e-POWER, with the 84bhp 1.4 litre Opel engine only driving the range-extender generator.

The Volt’s drive system is a clever piece of design, with a planetary gear set allowing the generator to operate as a secondary traction motor when the control system senses high power demand. Even at a late stage of development, GM described the upcoming Voltec system as a battery electric vehicle with a discrete IC engine performing only a generation function. When the patent for the Voltec system was granted, not long before the car’s launch, observers were taken aback to find out that the planetary gear train now included a third gear and clutch pack which took drive from the petrol engine directly to the transmission.

The reason for this was that, in test cycles, involving highway driving, it was found that the process of generating three-phase AC electrical power, then converting it to DC in the inverter to charge the battery, then back to AC to drive the traction motor was only 70% efficient. The ‘efficiency deficit’ was reduced to a more acceptable 15% by introducing direct drive from the petrol engine to the gearset. The Volt had become a parallel / series hybrid, although differentiated from the Prius and Honda Insight by its plug-in charging capability and much longer electric-only range(4).

Image: Car Magazine

Unlike the Nissan system, the Voltec design cannot operate with a discharged traction battery as the main electric motor regulates the other power sources – if it stops delivering energy to the sun gear, the planet gears will spin freely with no power going to the final drive. The Volt, as a plug-in hybrid has a much larger battery than the Qashqai; 16kWh compared with 2kWh.

Nissan’s determination to bring e-POWER to Europe in the Qashqai J12 is a bold venture, particularly as its engine range has no high combined output plug in-hybrid  powertrains on offer for those wanting something heftier yet more tax efficient than the small petrol turbos present offered. Price and promotion are likely to decide e-POWER’s success.

 

(1) Nissan states that these numbers are ‘Pending final homologated values’.

(2) I would much prefer it if they instead paid attention to the road ahead, and even took an occasional look in their rear-view mirrors.

(3) Toyota offered a plug-in Prius from 2012, rather under sufferance as they considered that the extra battery weight compromised the overall efficiency and technical purity of their self-charging hybrid system.

(4) The 16kWh battery of the early Volts was downrated to around half that capacity to slow down battery degradation. Later Volts and Amperas had increased battery ratings, and an improved battery-only range.

24 thoughts on “I Can Explain Everything. Actually, No, I Can’t.”

  1. I am a member of the steam locomotive footplatemen, but I consider myself modern as someone I know owns horses 😉

    E-power basically sounds like a Fisker Karma drivetrain in a Nissan? I like the idea as batteries are still heavy and I prefer lightweight vehicles above the 2,5 tonnes Teslas and that ilk. BMW was rumored to have the same idea some 10 years ago, but I haven’t really heard about that for a long time.

    Having said that I know things are changing and I am not against change. For me personally electrical cars have little appeal as they are still expansive and still have too little range. The shortest trip I do is 100 kilometers one way, the longest just over 250 kilometers one way. I like to be able to make trips like that back and forth without the need to charge in between and I like to do it in winter too with the heating on. So 500 kilometers highway travel in winter with the heating on is the minimum for me. Either that or the charing time needs to be reduced more than it already has, but I don’t find the idea of stopping every every hour and a half or so to charge appealing, even if it’s only for a couple of minutes. It will be different for anyone else.

    And let’s not forget that situations are different in different areas of the world. To sell cars globally it’s still good to have BEV’s and ICE-powered vehicles as well as hybrids I reckon.

  2. Good morning Robertas and thank you for an excellent explanation of Nissan’s new powertrain. I must be missing something, however, as I am completely mistified as to the point of it all. The petrol engine will be running almost all of the time, and the power losses in converting the electricity generated to D.C. to charge the battery, then back to A.C. to power the motor, must be significant, not to mention the extra weight and complexity of the drivetrain. Does it suffer from disconcerting engine noise that is unrelated to road speed, like a CVT automatic set-up? The stepless power delivery of the electric motor could largely be replicated by a good dual-clutch automatic.

    1. There are quite a few e-Power propelled Nissan Notes here in NZ, having been imported used from Japan. I believe there are plans by Nissan to sell them new in NZ soon.

      Having driven one, it’s actually quite pleasant. You don’t really hear the engine much at all, but you do get to enjoy the instant torque from the electric motor, plus a decent amount of regeneration if you prefer the one-pedal driving style option.

      Speaking to those who have them, economy overall seems to be pretty consistent and quite a bit better than the small Toyota hybrids. One person I know is averaging around 24km/l, which includes commuting and round town running. An 800-1000km range is readily achievable.

      Doing away with the complexities of a mechanical gearbox and replacing it with an electric motor (and the benefits it brings) seems like a good move. It allows you to tune the engine to run more efficiently over a smaller range of working conditions. We also have to remember that there are many places in the less developed world (and even the developed world outside some main centres) where a pure EV is simply not (yet) an option.

    2. Hello Paul – funnily enough, I’ve just been watching a short video about the e-POWER Note to try to understand the concept better. It seems one gets an EV experience, as you say, with a range of up to 1,300 km on 47 litres of fuel, which is 78 mpg. I assume that this vehicle would be a lot more efficient in urban environments, compared with a traditional set-up.

    3. Daniel, as I understand it the reasoning is that the benefits of running the engine at a fixed and economic speed outweigh the reduced efficiency. E-Power was originally sold only in Japan and then migrated to neighbouring and RHD markets where low speeds and dense traffic are common. In this scenario hybrids of any persuasion are at their best as the frequent stops mean that otherwise wasted energy can be recovered. Don’t forget that E-Power is still a hybrid in that the motor can reverse itself and charge the battery.
      The downside is that the system, like any hybrid, is less suited to sustained high speeds as the possibilities for recovery of energy are reduced and the need to run the engine almost continually means that the inherent inefficiencies come to the fore. Other makers get around this by using mechanical drive at cruising speeds – Honda’s Twin Motor system differs from E-Power only in that it connects the engine directly to the wheels in the kind of situation where a manual car would be in sixth gear.
      I was initially surprised when Nissan announced the arrival of E-Power to Europe and assumed that it would be modified along the lines of the Honda system but seemingly not.

  3. Another consideration is since we are part of “the system” we have to adapt and change our perspectives on the right of movement and how its achieved, in other words evolving and however painfull for some this is happening as we witness it.
    The internet has provided man kind a means of eliminating physical travel and yet elders still
    yearn for it without the negatives.
    Extended charge/ rest stops just may become the new normal for todays generation, I for one
    recently found a break at the UK’s Braintree Gridserve charge station a most pleasant experience.

  4. Like Daniel, I am struggling to see the point – power, torque and even emissions are nothing special at all, so why go to all the bother?

  5. I’m surprised this hasn’t been done before; it’s essentially a petrol car version of the “Diesel electric” system used on railway engines since the 1930’s.

    I always assumed that it would promise a saving in transmission weight over a “conventional” car but that is only a guess, for a manual fwd set up it might be negligible or perhaps even heavier(?).

    It is probably best thought of as a system with a simplified operation; one pedal, no gears. All the benefits of a torque converter or CVT operation with fewer drawbacks.

    The GM “Voltec” system is interesting and suggests how electrical transmission equipment has only crept foward incrementally over the decades if at all. According to railway guru O.S Nock 1960’s diesels had a transmission efficiency of about 81% (Components were around 90% efficient, so generator x traction motor- or 90% x 90%- equals 81%). This was typically reflected in the difference between engine horsepower and power at rail. As a big (Former?) diesel locomotive manufacturer GM would have been aware of this and probably used it as a target efficiency for the Ampera/Volt. By my reckoning they got an 85% efficiency by mechanical drive to the wheels, suggesting that if they’d opted for a dc generator x dc traction motor arrangement it still wouldn’t have been able to match the efficiency of direct drive, even though it would have been better than their AC to DC arrangement.

    As an aside Mazda uses what they coyly call a DC motor generator in their mild hybrids. That is a starter motor that doubles as the generator and assistive motor to give the car a bit of a boost. This is simpler than the third option shown in the diagram. However it raises intriguing posibilities about how much this was inspired by “Dynastarters”, a 1950’s vintage dynamo and weedy starter motor that some motorbikes of the era were “Blessed” with. Obviously it is more advanced than that in the Mazda but it suggests that some ideas for the future can come from the past.

  6. Doesn’t the current (hybrid-only) Honda CR-V use some kind of indirect drive system between the IC motor and the wheels? I’m sure I’ve read the details, without really understanding….

    1. Mervyn, the Honda system is very similar to the Nissan one in that it uses the engine to drive an alternator to drive the wheels with the intervention of a battery to recover energy, but it has a significant difference in that it uses mechanical drive at cruising speeds, basically when you would use sixth gear in a manual equivalent. The reasoning is that at a steady speed the losses involved a purely electrical system such as Nissan use are significant. There is after all a reason why electrical drive hasn’t been used in cars before (except for the outlier of the range extender version of the BMW i3).

    2. The Honda system – at least the i-MMD(Intelligent Multi-Mode Drive) one used from around 2014 – is similar to the Volt/Ampera’s in that the IC engine is not mechanically connected to the final drive under most driving conditions, but will be connected by the drive control management system in steady-speed highway use. The connection is achieved using a motorcycle-like multi-plate wet clutch.

      Otherwise there’s no conventional transmission – neither epicyclic, CVT, nor dual clutch. Honda seem to have followed up GM’s basic idea, added some of their own, but still found the same “efficiency deficit” which stood in the way of pure petrol-electric drive without any mechanical connection between the IC engine and the road wheels.

  7. Thank you Robertas for the technical description of this third engine version of the Nissan but, like Daniel, I didn’t really understand the point.

    They combine the disadvantages of an ICE (local exhaust fumes, is getting on the index in cities) with the disadvantage of an EV (weight). Well, due to the high energy content of a petrol tank, the technology is well suited for long range rides in the outback. But then why waste the transformation losses? For these operational area a ICE would suffice.

    So for me the only remaining advantage is the driving experience of an EV – quite a lot of effort just for that.

    But probability bordering on certainty I’m not the target group anyway – first I don’t need such a vehicle, and second I can no longer take Nissan seriously after the (non-)performance of the GT-R LM Nismo in the WEC in 2015 – so I don’t need to understand all this.

  8. I’ll add my name to the list of those who don’t get it. Would this even qualify as a hybrid technology?

    At the core of all this is the fact that the Japanese really seem to hate EVs and after some research, I found the link, below, which may give a bit more background. I didn’t realize that Toyota once had a stake in Tesla, but sold it. Oops. One final thought – ‘our’ (governments’) commitment to our eco goals is going to be tested by the energy crisis. It will be interesting to see how it holds up.

    https://electrek.co/2021/11/11/how-toyota-sneakily-spreads-anti-ev-propaganda-in-japan/

  9. Fair dues to Nissan for making this work where others failed. I’ve always wondered why all hybrids didn’t work this way – having a mechanical drive link seemed atavistic once an electrical drive system was in place. DP’s comment about losses at a steady state cruise explains that.
    I’d actually like to know more about the way current diesel-electric rail units work: some of the ones I’ve travelled on give a distinct impression of possessing a gearbox, with engine revs audibly rising, then suddenly falling as though there had been an upchange.
    As an aside, the GM diesel electric locomotives of the sixties and seventies are credited in some quarters as having saved the Irish rail system after the first tranche of diesel traction from Metropolitan Vickers proved unreliable. I don’t believe the more recent ones have done so well, although the UK has a large fleet of EMD (neé GM) JT42CWR locos for freight haulage.

    1. Michael, if you’re able to hear the engine in a train you’re probably in what’s called a DMU, a Diesel Multiple Unit, where each coach has an engine under it. These are typically not diesel electric – they use what the railway world calls diesel hydraulic drive where the engine drives the wheels through multiple fluid couplings each of which provides a different speed. So what you hear as the train changing gear is in fact the train changing gear!
      Some newer trains use conventional automatic gearboxes so the experience is even more like that of a road vehicle.

  10. Paul H – Your New Zealand experience with an e-POWER Note makes interesting reading. 24km/l translates as nearly 70 miles per UK gallon, the sort of figure usually only achievable with very small diesel engines in light cars of the sort we’re not allowed any more. There should be a good supply of Notes forthcoming, as by March 2021 Nissan reported that domestic market sales of e-POWER vehicles cars had reached the half-million, just over four years after the introduction of the powertrain in the 2017MY mid-term facelift Note. The Note was a regular top-seller in the years which followed, and 70% had e-POWER.

    Nissan have stated that e-POWER is “a key pillar of its electrification strategy.” This bears out Charles’ statement, following research, that “the Japanese really seem to hate EVs”. The electrek.co article on the Toyota-backed anti-EV propaganda is a great find, although it’s made me think less of Akio Toyoda.

    In the European context, the full – or ‘strong’ – self-charging hybrid, is being by-passed in the rush to PHEVs and full BEVs. I can’t help but think that the high-ups at Nissan HQ have imposed e-POWER on Europe to see if consumers can be persuaded of its advantages, and thereby emulate its success in the Japanese market. That’s my pragmatic view.

    My sceptical one continues to be that the European Nissan people are probably aghast, and wish the development costs had been spent on a PHEV option for the Qashqai, or adoption of the Rogue’s 200bhp+ variable-compression ratio engine as the high power option, possibly with the ELiS mild hybrid integrated with its CVT, which is the same Jatco unit as used in the Qashqai.

    1. Im wondering how this compares with the BMW i/3 range extender which favours a larger battery and smaller generator plus has plug in ability.

    2. I wondered that initially. The BMW has a large battery and a tiny engine, and is mostly charged by plugging it in.

      The Nissan has a normal engine that constantly powers a small battery and can’t be plugged in.

      One is an EV and the other is an optimized internal combustion powertrain.

    3. As DP aptly describes it, the BMW i3 REx system is an ‘outlier’. I’d unkindly describe it as just slightly better than carrying around a small petrol generator in the boot. The situation is further confused by the miniscule fuel tank stipulated by US regulations in order to qualify as a zero-emission vehicle. European versions weren’t much better – you could still be in a situation where after 150 or so miles the petrol tank is full but the discharged battery prevents further progress.

      BMW really shouldn’t have bothered with REx, and allowed the i3 to stand on its merits as a battery-electric vehicle.

      Which is not to say that some carmaker, somewhere in the world, might revisit the idea and make it work with today’s advances in EV technology. In EV terms, 2013 now looks like the Stone Age.

  11. Thank you Robertas for writing on this subject. The GM supplied numbers on thermal efficiency for the Voltec do not add up for me (or I think for GM, or they’d still be selling Voltec). The Nissan e-POWER’s series hybrid ICE component seems to deliver around a ~20% efficiency advantage over the ICE components of Toyota’s Prius and the Voltec, but the net thermal efficiency of the entire system is still nowhere near 85%.

  12. Robertas I have yet to experience a lack of travel using the i3 range extender with a depleted main battery so would have to disagree. The i3 battery maintains a buffer when indicating empty
    thus it is always powering the car with the range extender maintaining that buffer.
    Keep filling the tank which is equal to main battery distance or recharge the main battery at a charging station.
    BMW has now discontinued the extender after upgrading the battery providing an equivilant range.
    Stateside i3s can be hacked to give full capacity to the fuel tank which in reality is the same size as the European models.

  13. In the course of my researches I contacted Nissan’s UK media office to ask about prices and launch date for the e-POWER Qashqai, and was told that more would be revealed at an event in Spain towards the end of March.

    The event has been and gone, and AutoCropley’s Illya Verpraet has posted a useful synopsis. The focus of the event, held on a closed track was the Ariya – prices and specifications now confirmed, orders being taken, but the mid-2022 availability has since been thrown into doubt by the continued inability of Far-Eastern chip shops to deliver.

    Anyway, on to the e-POWER Qashqai. No prices, no on-sale date. According to Illya, the 1.5 litre triple is the turbocharged variable compression unit. If so, it’s considerably downgraded from the US Rogue (X-Trail) non-hybrid application; 156bhp as against 201bhp. Driving impressions are favourable – Illya is not a fan of the currently available Qashqais’ “underperforming” 1.3 litre mild hybrid powertrains, whether with the “obstructive” manual gearbox, or the “wheezy” CVT.

    Based on closed track experience, the e-POWER is “a better Qashqai in every way”. AutoCropley’s broader conclusion is that:

    “The bigger issue is that prices have not been announced yet. To pull off its series hybrid trick, the E-Power has a bigger electric motor and a bigger battery than most full hybrids. So it wouldn’t be surprising if the whole car ended up costing more than rivals. The Qashqai E-Power is one of the more convincing cars of its kind, but it will still need to be competitively priced if it is to earn our recommendation.”

    Which is very close to my own earlier uninfluential opinion, despite not being informed by on-track experience.

    As an aside, the data accompanying the AutoCropley report states a top speed of 104mph for the e-POWER Qashqai, as against 120-128mph for the mild hybrids. Could this restriction be Nissan’s way of dealing with the series hybrid’s “efficiency deficit” issue?

    1. Nothing in the AutoCropley report deflects me from my suspicion that the e-POWER Qashqai is just not going to happen, at least in Europe. Plenty of excuses are available – processor supplies, supply chain generally, and a far faster take-up of BEVs in Europe than anybody expected.

      All of that notwithstanding, Nissan need to sort out the Qashqai powertrains soon if they are to maintain their market share. A plug-in hybrid at the very least – Alliance partners Renault are doing this already with the Megane and Captur.

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