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Rotary as REX?
omg, Can I put my hope on a hybrid RX-7?
I miss everything about my FD3S except the eye watering mpg
it does make sense to use a wankel rotary as REX, it is light, compact, have less moving part compare to piston engine, low noise and less vibration.
 

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Whatever it was, the reason it died (and the i3 BEVx now appears close to the end) is that the ICEs in both vehicles were over-sized to meet the absurd requirement of providing kW output sufficient for normal driving (or nearly so) following battery depletion.
A much smaller on-board ICE generator with output as low as somewhere between 10 kW to 20 kW, supplied by a five to ten gallon fuel tank,

The i3 REx is a 650cc two cylinder scooter engine with 36HP in the LCI (facelift) version. REME (Generator) output is about 25kW. EU/UK fuel tank capacity is 9 litres or just under 2.4 gal-US. The US version has a smaller usable tank set in software to meet some obscure regulation.
 

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The i3 REx is a 650cc two cylinder scooter engine with 36HP in the LCI (facelift) version. REME (Generator) output is about 25kW. EU/UK fuel tank capacity is 9 litres or just under 2.4 gal-US...
And if any small BEVx was built using ~the same battery capacity, an ICEx ~half the size, and a fuel tank with three to four times capacity of the i3, it would cost less to manufacture, have higher efficiency (when utilizing grid/battery kWh) have ~twice the maximum range between refueling, and I would quite likely be driving one today.

...The US version has a smaller usable tank set in software to meet some obscure regulation.
Obscure or not, CARB staffers screwed up severely when they wrote the BEVx rules:

"California’s new ZEV rule introduces the BEVx; ARB staff expects these vehicles to play a longer-term role than plug-in hybrids

29 January 2012
On Friday 27 January, the California Air Resources Board (ARB) adopted the new Advanced Clean Cars (ACC) package that sets out the regulatory emissions and technology requirements for light-duty automobiles through model year 2025. (Earlier post.) The Zero Emission Vehicle (ZEV) regulation—one of the three main regulatory packages that constitute ACC—introduces a new regulatory vehicle category: the BEVx, or a battery-electric vehicle with a small “limp-home” range extending engine or APU (auxiliary power unit)—i.e., not a series-hybrid type vehicle such as the Chevrolet Volt equipped with a full-capability engine.
Under the ACC, ARB will award BEVx credits on the same basis as BEVs...

ARB staff suggested that the BEVx market may appeal to drivers who would not otherwise consider a BEV with the same range. Since staff considers these vehicles full function BEVs with short range APUs, it stressed the importance of having the minimum range for eligibility be equivalent to full function BEVs in the marketplace.
Basic criteria for these vehicle include:
  1. the APU range is equal to or less than the all-electric range;
  2. engine operation cannot occur until the battery charge has been depleted to the charge-sustaining lower limit;
  3. a minimum 80 miles electric range; and
  4. super ultra low emission vehicle (SULEV) and zero evaporative emissions compliant and TZEV warranty requirements on the battery system..."

I have had several conversations with assorted CARB staff on this subject over the years.

Apparently, the requirements that the APU range is equal to or less than the all-electric range and engine operation cannot occur until the battery charge has been depleted to the charge-sustaining lower limit were instituted in an attempt to idiot-proof BEVxs.

CARB staffers feared that, absent these design limitations, many drivers would be so seized by range anxiety that they would make a habit of firing up the ICE every time they drove their BEVxs.

Unfortunately, with those regulations CARB effectively snuffed out nearly the entire BEVx classification, with only the i3 ever being certified. And for added comic relief, many (most?) California/USA i-3 drivers apparently have (illegally) modified their i-3s to ~euro-spec to maximize their utility.

Back on-topic, I can only hope that Mazda either is engaged with CARB in revising these BEVx regulations, or is planning to certify their vehicles under another (less lucrative) CARB classification.
 

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Why Mazda thinks a smaller battery is just fine for the MX-30


At first glance, you might think that Mazda has made a serious mistake with the MX-30 electric compact crossover.
Automakers are racing to ease customers’ anxiety about electric vehicles by fitting larger and larger batteries that permit 400 km of range or even more. But Mazda has given the MX-30 a 35.5. kilowatt hour battery pack, resulting in a range of about 200 km.
And there isn’t really a price benefit, either: The similarly sized Hyundai Kona EV, which has a 39-kWh battery pack that permits 289 km of range under the WLTP cycle, is priced at about 38,000 euros, compared with the MX-30's expected price of about 35,000 euros.
Not so, Mazda says. It is simply taking a different approach in deciding to give the MX-30 a smaller battery pack.
Or, in the words of Christian Schultze, director and deputy general manager at Mazda Europe’s r&d center, it is giving the new model a battery pack that is “responsibly” sized.
Mazda is basing this claim on a life-cycle assessment of total CO2 emissions, saying that the MX-30 with a 35.5 kWh battery pack is comparable to a diesel Mazda 3 compact hatchback (see chart, below) on that basis. Schultze said that even after replacing the battery pack, something that could occur after 160,000 km (100,000 miles) of use, the MX-30's total CO2 emissions are still similar to the diesel’s.
Mazda says that a 95-kWh battery pack would have substantially higher CO2 emissions from Day One, both from the production of the larger pack and higher electricity consumption. And when that larger pack needs to be replaced, overall emissions will jump again, Mazda says...
http://a.idio.co/r?a=consume&e=190488&o=1905&d=1905&u=https%3A%2F%2Fwww.equinix.co.uk%2Fresources%2Fwebinars%2Fdigital-industrial-revolution%2F&c=automotivenews&q=1f7bd970-769d-40d3-a404-97c4f6da081d&x%5Bidio%5D=530371728




One caveat to Mazda's comments would be that a larger battery would probably last much longer.

However, if past experience is any guide, battery packs produced today will approach obsolescence in only ~5 years anyway.

And if Mazda's battery lasts for ~10 years and ~100k miles with only ~20% degradation (as seems likely) AND with the capability to recharge as you drive, the BEVx concept seems superior to the half-ton-battery plan.
 

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Hmm, I expected then to cite weight as the reason.

If Mazda and Honda offered a larger pack for 3-4k more, which is basically what the Hyundai pack upgrades cost, I'd take it.
 

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That's effectively their point and they have done the analysis based on a low mode average usage where there is little advantage to the bigger pack and the additional weight is an issue. How the REx might compare in a high mode average usage would be interesting to know.
 

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I think for a lot of people it's a 99/1 problem. Like there are a few times a year when a bigger battery would be of use so it's not really worth paying a lot more and carrying the extra weight and compromising the layout and handling of the car just for that.
 

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That's effectively their point and they have done the analysis based on a low mode average usage where there is little advantage to the bigger pack and the additional weight is an issue. How the REx might compare in a high mode average usage would be interesting to know.
I think for a lot of people it's a 99/1 problem. Like there are a few times a year when a bigger battery would be of use so it's not really worth paying a lot more and carrying the extra weight and compromising the layout and handling of the car just for that.
I was flicking through a car mag over Christmas and the MX-30 was mentioned, and I found myself agreeing with Mazda’s thinking around battery sizes, and not just because I happen to own a 35 ish kWh EV at the moment.

When I had my first gen i3 (with a Rex) I kept thinking that a car with 120 miles of electric range would be perfect for me, now I have a car with such range and occasionally I think that 200 would be ideal. Where does it stop though?

There are already a lot of big battery EVs out there that are being woefully underused, and the ‘spare’ battery capacity could be being put to use in thousands more smaller battery EVs. Even if those batteries are being used to complete journeys rather than just for the performance aspects that a bigger battery brings, then the efficiency is hardly anything to write home about.

My thoughts now are that it’s surely ‘better’ to take a moderately sized battery pack and sweat it properly on a daily basis, and charge it as required for those occasional beyond range longer trips as required (accepting the time penalties).

For that to be possible though, we need an abundant and reliable charging infrastructure. The lack of that infrastructure is driving thinking for bigger batteries, to be independent of said public charging infrastructure, but I’d be happier with a smaller and lighter EV that could be reliably and quickly recharged wherever I needed to take it.

Globally, it’s still early days, but it does feel like we’re making the same mistakes with EVs that we've been making with ICE vehicles for years.
 
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