BMW i3 Rex Run.

Used 6% for 38 Kms at 120 Kph, good or bad ? considering it would drop a hell of a lot faster without the Rex I consider it excellent. When you slow down it actually creeps back up. At lower speeds it probably won't go down at all unless climbing some steep hills.

Had to make an emergency run to the hospital with my 2 year old Son, all good , more of a precaution after the last time we had to bring him.

Anyway, I didn't bother to charge the car last night ( didn't think I was going anywhere) , but it was about 50% full which is just above what the 24 Kwh leaf would have been at 100% charge but I did not have to reduce speed kept to 120 where I could on the M9 then 100 to Kilkenny hospital and the same on the way home. The leaf range would have been quiet low enough at that speed in this weather. Used the Rex on the Motorway the entire way then battery the rest from M9 turn off to hospital and same on the way back, Rex on Motorway and Battery last few Kms.

That's the first time in nearly 3 weeks I used the Rex. That's some efficiency out of 9 litres of petrol and still have half a tank lol.

I used to be against having an engine or generator but I think this is really fantastic, means smaller battery for 98% of your driving and the engine for the rest and I really think more manufacturers should go this direction until battery costs come down and manufacturing is greatly ramped up and charging time greatly reduced.

More environmentally friendly needing a lot less battery ?

If there were many more chargers and I could charge in half the time I'd say fair enough I don't need a Rex but my closest CCS charger is the dodgy charger in Naas, there's 0 from Naas to Waterford on the M9. But even if I still had the 24 Kwh Leaf I'd have had to charge at Barlo on the way home if driving at that speed from 100% charge and charging the Leaf would have been pretty slow with a cold battery.

Yes, I really think manufacturers should offer a 20-30 Kwh battery and then people can use generator for the rest, something that never drives the wheels directly like the i3 , It eliminates range anxiety and would attract a hell of a lot more people to EV. Means you don't have to fast charge but you still have the choice.

The Rex is a no compromise vehicle, truly delighted with it , means I can take it anywhere. Charge if I want or not or drive on, charger down ? or in my case today no charger anywhere near me and AC points way too far away, either way no worries, just get in and drive.

unkel

It's an embarrassing state we're in that we still kinda need ICE for some of our needs. And as such, I am no fan of hybrids, plug in hybrids or EVs with an ICE as a range extender. EV only is the only way forward.

That said, in the state we're in, there really isn't that much choice and availability of pure EVs to suit most peoples needs. And a car like the i3 REX seems to be a much better fit for most people currently owning a Leaf, like yourself. With the huge benefit that you can use the battery range 100% all of the time without any range anxiety, because you know the engine will kick in and will always bring you to a nearby petrol station.

tl;dr REX in theory should be frowned upon, worst of both worlds / in practice it really works at the moment until we get bigger batteries

Yes we'd all like more EV range but at some point you'll still need public charging.

Leaf could have sold in huge numbers if it had a rex like generator, this would have been the perfect solution until the network caught up and until battery costs dropped and also energy density increased to the point you could have 60+ Kwh in the same size and weight as 20 Kwh.

Could it be that faster charging is the way to go in the short term, if I could charge the i3 in 5 mins to 80% or even 10 mins from 6% I'd say fair enough but that increases reliance on the network and if I have 60+ Kwh then I'm carrying around a huge heavy battery I don't often need.

A generator means much less battery is needed but still burns petrol but is that so bad V the current manufacturing of batteries ? Petrol is being refined anyway and phev's with such large batteries would greatly cut down the amount of petrol needed.

If manufacturers had coped on to this long ago they could have had an i3 equivalent , especially Toyota. On such vehicles there should be the same VRT relief as given to BEV cars to keep costs down, higher VRT on the i3 is an insane Joke.

zilog_jones

Do you find the ICE noisy at all when it's running? Does the engine speed change much depending on load?

There's serious potential for Mazda in this field, as rotary engines are very compact, smooth running, and can actually be efficient when running at a constant speed i.e. as a generator (as opposed to normal car application, where fuel consumption is pretty awful), but it seems smaller manufacturers just don't have the resources to get into this business...

n97 mini

zilog_jones wrote: »

There's serious potential for Mazda in this field, as rotary engines are very compact, smooth running, and can actually be efficient when running at a constant speed i.e. as a generator (as opposed to normal car application, where fuel consumption is pretty awful), but it seems smaller manufacturers just don't have the resources to get into this business...

You're possibly conflating turbines and rotary engines. Turbines are efficient, rotary engines are not. Unequal compression (which is an inescapable part of the design) leads to incomplete ignition which in turn gives poor emissions and economy.

zilog_jones

I'm talking specifically about Wankel engines, which Mazda call "rotary" engines. I don't know how efficient the can be exactly, but by running them at a constant speed you can certainly maximise their efficiency:

http://www.telegraph.co.uk/motoring/news/9550675/Mazda-stays-loyal-to-rotary-engines.html

"The rotary engine has very good dynamic performance, but it's not so good on economy when you accelerate and decelerate. However, with a range extender you can use a rotary engine at a constant 2,000rpm, at its most efficient. It's compact, too."

The small packaging and refinement compared to piston engines are still a big potential advantage. Mazda love their rotaries too much to ever give up on them, and have been trying to solve other problems with them (e.g. emissions) in past years. They may even have something out in a couple of years: https://www.motoring.com.au/tokyo-motor-show-mazda-outlines-ev-plans-109553

Audi and a few others have made range extender prototypes using Wankel engines, but don't know if they'll ever go into production.

The Mazda2 EV prototype had a single-rotor 330c engine delivering nearly the same amount of power as the i3 REx ICE (22 vs. 25 kW), and including fuel tank and ancillaries only weighed about 100 kg.

n97 mini

That Telegraph article is from September 2012!

I don't think we'll ever see a rotary engined rex. For the reasons outlined (uneven compression) Wankel engines can never be as efficient as reciprocating engines.

zilog_jones

The second link was based on an announcement during the Tokyo Motor Show two months ago, they seem to be committed to releasing a rotary-based range extender EV in 2019:

https://www.autocar.co.uk/car-news/motor-shows-tokyo-motor-show/mazda-bring-back-rotary-engine-range-extending-hybrid

But in that announcement it's clearer that they're looking at rotary more for refinement than efficiency. I think the point still stands they'll be more efficient than direct drive rotary engines at least.

zilog_jones

zilog_jones wrote: »

Do you find the ICE noisy at all when it's running? Does the engine speed change much depending on load?

There's serious potential for Mazda in this field, as rotary engines are very compact, smooth running, and can actually be efficient when running at a constant speed i.e. as a generator (as opposed to normal car application, where fuel consumption is pretty awful), but it seems smaller manufacturers just don't have the resources to get into this business...

You can hardly hear a hum from it , they suppressed any noise very well.

zilog_jones

zilog_jones wrote: »

The second link was based on an announcement during the Tokyo Motor Show two months ago, they seem to be committed to releasing a rotary-based range extender EV in 2019:

https://www.autocar.co.uk/car-news/motor-shows-tokyo-motor-show/mazda-bring-back-rotary-engine-range-extending-hybrid

But in that announcement it's clearer that they're looking at rotary more for refinement than efficiency. I think the point still stands they'll be more efficient than direct drive rotary engines at least.

It's no good though unless they have a 20 Kwh + battery.

zilog_jones

[Deleted User] wrote: »

It's no good though unless they have a 20 Kwh + battery.

The prototype Mazda2/Demio had a 20 kWh battery with this ICE, though that was a good few years ago now.

zilog_jones

zilog_jones wrote: »

The prototype Mazda2/Demio had a 20 kWh battery with this ICE, though that was a good few years ago now.

Did it ? shame it never came to production.

Plug ins won't be so popular here due to the extra VRT, the Government should eliminate VRT on all plug ins with a 20 + Kwh battery.