Ok, I am skeptical of non-EPA reports of cars whose existence is documented by press releases and rewrites by automotive press. There are a few exceptions but for the most part, I am skeptical. However, I have grown fond of Robert Llewellyn's efforts over the years and I found something in his latest review: Apparently Kia is feeding the electric motor power through the transmission. Today's EVs are often single gear-ratio transmissions. At low speed, the torque makes gears redundant but at higher speeds, the back EMF limits the power. If you want high speed, the motor needs to be geared for slow rpm and that is what Kia has done. But how fast do you need to go? Recently there is a report that the Hyundai Ioniq has set a speed record for hybrids. Piece of cake if you run the motor through a transmission to gear it down. Bob Wilson
Gears can help a lot, but can also have some problems with maintenance. From the mechanic point of view, our HSDs are a lot simpler.
Worth noting that the Sonata/Optima have had a version of this setup - pancake motor driving through a 6-speed automatic - since model year 2011 in the US. Really, it's a similar idea to Honda's old IMA system (but with an added clutch to allow the electric motor to drive the vehicle without the engine running, and with a conventional automatic instead of a manual or CVT), to Volkswagen's various hybrids over the years (although some of those use a 6 or 7-speed DCT instead of a conventional automatic), to Nissan's current hybrids (but with a conventional automatic instead of a CVT), or to the Ioniq/Niro (but with a conventional automatic instead of a DCT). There are some EVs with 2-speed gearboxes, the Rimac Concept_One has a 2-speed DCT for each rear motor (single-speed on the front motors, though). And, the Lexus LS 600h L and GS 450h have a 2-speed reduction box on the end of their power split device, which I'd say counts. LC 500h, and presumably the next-gen LS hybrid, will have a 4-speed reduction box, although this is apparently more for sportier driving characteristics (that is, closer to those of a conventional automatic, than a CVT), than for efficiency?
I was thinking about a geared electric motor and realized that it may lead to higher efficiency in some partial power bands. So I started a Google search and sure enough, motors have efficiency curves and in some cases peak efficiency in a subset of the torque-rpm band. Thinking about it, there are parasitic core losses at higher speeds as well as mechanical and capacitive losses. The secret of Prius efficiency has been running the Atkinson engine in peak efficiency power range and use the hybrid transmission and battery to handle the inefficiency power needs. But the same rule can be applied to the electric motor and that may be what is behind: 2017 Hyundai Ioniq Electric Steals Energy Efficiency Title From Toyota Prius Prime | CleanTechnica Bob Wilson
I'm trying to remember when I last had to wait behind someone to refill petrol. In my area, you can't make a living running a gas station if it doesn't have 8 pumps and many places have double that. It could have occurred during a gas pipeline shutdown. But then there have been two of those, one tornado and one hurricane that took out Electric power for a significant time during the same time period (which in our area shuts down the petrol pumps too). And why should I worry if I generally have 500 miles in the tank. We are all creatures of our own experiences, circumstances and biases.
It is worth noting that in electric bicycles, efficiency seems to go something like this, in increasing order, if you don't do regenerative braking, IIRC: Direct-drive hub motors (very heavy, extremely low RPM (in the ballpark of 300-400 RPM tops), and lamination thickness on most of them results in decently high cogging losses, although some companies are starting to work on this) Geared hub motors (much lighter, higher RPM (typically 5:1 or so reduction gearing), and freewheeling typically, removing cogging losses from the equation) Mid-drive motors (using the bicycle's gearing in addition to their own gearing, so they can spin at whatever RPM's most efficient, and target around 60-90 RPM at the sprocket to optimize efficiency for both motor and rider, and freewheeling) The caveat is that regenerative braking does give gains, and you have to go direct-drive to get it. (You don't have to, but freewheelless geared hub motors are extremely uncommon, and most sane applications of a mid-drive would have a freewheel at the back. Then again, there's the NexxtDrive Gemini, which is basically a human-powered power split device, and the planned mid-drive version would have to be specced to use a fixed gear rear hub to get regenerative braking - I think the pedals are on a freewheel though inside of it. If I got a hold of one of those, though, I'd actually want the rear hub version - the vehicle I'd plan on using it on would have a somewhat inefficient chainline, that would be a pain in the rear to adjust if it had to handle torque in two directions (no tensioners allowed).
I have been thinking about the 'last mile' problem of EVs since I got my BMW i3-REX. For me, parking at a charger simply means an opportunity to take a walk up to 1/2 mile. This is good for my heart but sometimes you want to go a bit further. For example, there are six, 16A chargers about half a mile from work but there is no direct path. Instead, you have to walk the outside of blocks. So I've been thinking about an electric skate board / scooter, top speed 10 mph, no faster than I want to fall. My tentative requirements are: Easily stowed in back of BMW i-3 REX Brake Handle uneven surfaces Range ~5 miles (you have to go and return without a charge) Speed ~10 mph 120 VAC charger Bob Wilson
