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I hate being a naysayer - this is cool technology - but the energy economics won't work out for metal-air batteries if they're used as the main power source. Re

by marvin 12y ago

I hate being a naysayer - this is cool technology - but the energy economics won't work out for metal-air batteries if they're used as the main power source. Recharging a metal-air battery is grossly inefficient, and a big part of the advantage with electric cars is that they use less energy in every step of the process except initial manufacturing. This means that the general economics of metal-air batteries will not work out either, because the system requires a physical supply chain that is much more expensive to build out than the electricity distribution network that already exists. Add to this that range anxiety is for the most part eliminated with >60kWh electric vehicles, and this is a no-starter. Where metal-air batteries could have a place, is as a trickle charging device that will be replaced only rarely, perhaps during an annual checkup, and used as a backup only on the few occasions where fast charging is unavailable or unwanted. But battery vehicle companies are onto this idea already - the Tesla Model S has space for what some suspect is in fact an upgrade slot where a metal-air trickle charging battery can be installed. The problem is, most mainstream news articles writing about progress in battery-electric vehicles are already far behind the state of the art. Tesla's innovation and execution in this space has largely removed range anxiety for all but a small (<5%) number of trips, and already have a very strong quick charging presence in multiple countries. The future is electric and is already here - most people just haven't noticed.

greglindahl 12y ago
Huh, the article addresses this issue pretty directly -- did you read it? Because the car would still rely on its regular rechargable lithium-ion battery most of the time and would switch to the aluminum-air battery as a backup only if the lithium-ion battery ran out, and because most car trips are 50 kilometres or less, Alcoa estimates the aluminum-air batteries would only need to be changed about once a year.
- pocketstar 12y ago
  Yes but then you are hauling around an extra 100kg of unused batteries for 95% of your trips.
  - pkulak 12y ago
    The BMW i3 Rex carries around about that weight right now for it's gas generator, plus tank, and it will only go 50 miles or so once the battery runs down! Since it seems to be selling just fine, people are obviously willing to spend weight to get range. Think how much lighter the Volt would be with no gasoline engine! And they also don't mention if you can choose how much to lug around. Maybe I think I'll only need 500 miles of extra range a year and I can carry around a pack half the size? I'd do that, even in the fast-charge plentiful northwest. It would be nice to have the freedom to skip a station and make some time instead.
    - mikeash 12y ago
      I figured that 50 miles for the BMW had to be wrong, it's way too small, but I looked it up and it's about right. Officially it's more like 70 miles, but that's still ridiculously small. I have to really wonder what the point of that option is. I get it for the Volt, you're pure electric for most of your trips, but you have gas range when you need it. But here, you still have typical crappy pure electric range, but with all the complexity of a hybrid system, and all the cost of burning gasoline for the last half of it. Why would anyone buy this?
      - pkulak 12y ago
        Well, it's a pure series hybrid, so, apart from the engine itself, it doesn't actually add too much complexity. It's a very small engine (650cc motorcycle engine) and there's never any direct connection to the drivetrain. The Volt engine is 1.4 liters and there's several clutches to hook it into the drivetrain at various speeds/modes. The BMW Rex is so close to perfect, that I think a lot of people are getting it with the hope that maybe they will be able to swap in a larger tank somehow later down the road. The tank right now isn't even 2 gallons. It's pathetic, and done to get some kind of damn sticker in California, not for any practical reason. Make that a 6-gallon tank with some after-market solution, though, and you've got a car with an 80-mile electric range and then several hundred more miles on gas for road trips.
        12y ago
esbonsa 12y ago
"... and a big part of the advantage with electric cars is that they use less energy in every step of the process except initial manufacturing." The most important part for me for electric cars is the simpler power-train system which is less likely to break... which is why i would never buy an hybrid that has both systems.
- mikeash 12y ago
  Oddly, hybrids seem to be really reliable, despite the additional stuff to break. Priuses get top marks for reliability. I'm not sure why, but I imagine it comes down to the electric stuff being extremely reliable due to the nature of the beast, and the gasoline end being treated more nicely (more consistent RPMs and throttle settings, no idling, not being used at all for a substantial fraction of your miles) more than compensates for the tiny increase in potential failures from adding the electric system. Also consider that there is essentially no transmission in the more advanced hybrids, which removes a potentially expensive breakage that regular gas cars are subject to.
  - esbonsa 12y ago
    top marks where? I don't see it... here is one source: http://www.usatoday.com/story/money/cars/2014/02/12/used-cars-less-dependable-jdpower/5403139/ http://www.usatoday.com/story/money/cars/2014/02/12/used-car...
    - mikeash 12y ago
      I didn't have any specific source in mind when I made that comment, it's just something I've seen in general. To double-check, I did a Google search for "most reliable used cars", then clicked on the first five links that didn't involve a price ceiling. Four out of five listed the Prius as being among the most reliable. For reference, here are the links I found: https://autos.yahoo.com/blogs/motoramic/car-dealer-scientific-guide-10-best-used-vehicles-181842236.html https://autos.yahoo.com/blogs/motoramic/car-dealer-scientifi... http://www.forbes.com/pictures/ehmk45iidj/toyota-prius-2/ http://www.forbes.com/pictures/ehmk45iidj/toyota-prius-2/ http://editorial.autos.msn.com/18-most-dependable-cars-on-the-road-1#2 http://editorial.autos.msn.com/18-most-dependable-cars-on-th... http://www.edmunds.com/car-reviews/best-used-cars-2013.html http://www.edmunds.com/car-reviews/best-used-cars-2013.html http://wallstcheatsheet.com/automobiles/10-most-dependable-cars-on-the-road.html/?a=viewall http://wallstcheatsheet.com/automobiles/10-most-dependable-c... (This is the one without a Prius, but even this one has a hybrid on the list in the form of the Volt.) Anecdotally, I seem to see a disproportionate number of the original Prius on the road still, despite only selling 54,000 of them in the US, and being over a decade old at this point. That could, of course, just be confirmation bias or local demographics.

by marvin 12y ago

greglindahl 12y ago

Huh, the article addresses this issue pretty directly -- did you read it? Because the car would still rely on its regular rechargable lithium-ion battery most of the time and would switch to the aluminum-air battery as a backup only if the lithium-ion battery ran out, and because most car trips are 50 kilometres or less, Alcoa estimates the aluminum-air batteries would only need to be changed about once a year.

pocketstar 12y ago
Yes but then you are hauling around an extra 100kg of unused batteries for 95% of your trips.
- pkulak 12y ago
  The BMW i3 Rex carries around about that weight right now for it's gas generator, plus tank, and it will only go 50 miles or so once the battery runs down! Since it seems to be selling just fine, people are obviously willing to spend weight to get range. Think how much lighter the Volt would be with no gasoline engine! And they also don't mention if you can choose how much to lug around. Maybe I think I'll only need 500 miles of extra range a year and I can carry around a pack half the size? I'd do that, even in the fast-charge plentiful northwest. It would be nice to have the freedom to skip a station and make some time instead.
  - mikeash 12y ago
    I figured that 50 miles for the BMW had to be wrong, it's way too small, but I looked it up and it's about right. Officially it's more like 70 miles, but that's still ridiculously small. I have to really wonder what the point of that option is. I get it for the Volt, you're pure electric for most of your trips, but you have gas range when you need it. But here, you still have typical crappy pure electric range, but with all the complexity of a hybrid system, and all the cost of burning gasoline for the last half of it. Why would anyone buy this?
    - pkulak 12y ago
      Well, it's a pure series hybrid, so, apart from the engine itself, it doesn't actually add too much complexity. It's a very small engine (650cc motorcycle engine) and there's never any direct connection to the drivetrain. The Volt engine is 1.4 liters and there's several clutches to hook it into the drivetrain at various speeds/modes. The BMW Rex is so close to perfect, that I think a lot of people are getting it with the hope that maybe they will be able to swap in a larger tank somehow later down the road. The tank right now isn't even 2 gallons. It's pathetic, and done to get some kind of damn sticker in California, not for any practical reason. Make that a 6-gallon tank with some after-market solution, though, and you've got a car with an 80-mile electric range and then several hundred more miles on gas for road trips.
      - 12y ago

esbonsa 12y ago

"... and a big part of the advantage with electric cars is that they use less energy in every step of the process except initial manufacturing." The most important part for me for electric cars is the simpler power-train system which is less likely to break... which is why i would never buy an hybrid that has both systems.

mikeash 12y ago
Oddly, hybrids seem to be really reliable, despite the additional stuff to break. Priuses get top marks for reliability. I'm not sure why, but I imagine it comes down to the electric stuff being extremely reliable due to the nature of the beast, and the gasoline end being treated more nicely (more consistent RPMs and throttle settings, no idling, not being used at all for a substantial fraction of your miles) more than compensates for the tiny increase in potential failures from adding the electric system. Also consider that there is essentially no transmission in the more advanced hybrids, which removes a potentially expensive breakage that regular gas cars are subject to.
- esbonsa 12y ago
  top marks where? I don't see it... here is one source: http://www.usatoday.com/story/money/cars/2014/02/12/used-cars-less-dependable-jdpower/5403139/ http://www.usatoday.com/story/money/cars/2014/02/12/used-car...
  - mikeash 12y ago
    I didn't have any specific source in mind when I made that comment, it's just something I've seen in general. To double-check, I did a Google search for "most reliable used cars", then clicked on the first five links that didn't involve a price ceiling. Four out of five listed the Prius as being among the most reliable. For reference, here are the links I found: https://autos.yahoo.com/blogs/motoramic/car-dealer-scientific-guide-10-best-used-vehicles-181842236.html https://autos.yahoo.com/blogs/motoramic/car-dealer-scientifi... http://www.forbes.com/pictures/ehmk45iidj/toyota-prius-2/ http://www.forbes.com/pictures/ehmk45iidj/toyota-prius-2/ http://editorial.autos.msn.com/18-most-dependable-cars-on-the-road-1#2 http://editorial.autos.msn.com/18-most-dependable-cars-on-th... http://www.edmunds.com/car-reviews/best-used-cars-2013.html http://www.edmunds.com/car-reviews/best-used-cars-2013.html http://wallstcheatsheet.com/automobiles/10-most-dependable-cars-on-the-road.html/?a=viewall http://wallstcheatsheet.com/automobiles/10-most-dependable-c... (This is the one without a Prius, but even this one has a hybrid on the list in the form of the Volt.) Anecdotally, I seem to see a disproportionate number of the original Prius on the road still, despite only selling 54,000 of them in the US, and being over a decade old at this point. That could, of course, just be confirmation bias or local demographics.