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Battery powered cars are slowly becoming more prevalent. But are they worth it due to the limited life of the battery? As well as the expensive battery replacement costs. I personally think that fuel cell technology would offer an better energy density. If all of the problems could be worked out of course. What do you all think?
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I think that the phrase 'if all the problems could be worked out' has equal validity when applied to either technology.
The bottom line is that the most likely way those problems are likely to be worked out is if there is a multitude of well-funded actors working to solve them and - barring a unexpected breakthrough at a university or national lab somewhere - that sort of development usually takes place through the private sector. Which in this case means the companies working to make battery powered cars. But in order to develop them, and advance the technology, there has to be an ongoing and growing market for them.
It's really a type of feedback loop.
Fuel cells may eventually develop to the point where they compete with and/or supplant batteries or batteries may eventually develop such that the issues of battery life etc. are resolved or improved where they dominate.
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Supposedly Tesla batteries retain ~95% of capacity after 200,000 miles of driving. Few people drive that far before upgrading their car anyway. Are there any fuel cell cars on the market? I know there are a few experimental buses in London. What’s driving the growth of electric cars is that the technology has reached the point of being competitive with petrol in terms of range and lifespan and increasingly huge mass production is bringing unit cost down. I’m not sure anyone is doing that with fuel cells.
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(01-19-2018, 10:11 AM)Rhea47 Wrote: Battery powered cars are slowly becoming more prevalent. But are they worth it due to the limited life of the battery?
Well...a few points about the limited lives of cars and what's worthwhile in them:
Based on evaluation of 126 customer-operated Teslas that drove a total of millions of miles, the battery packs retained 80-85% of their life after 100,000 miles. That's still a useful range, and the replacement of the battery pack is cheaper than a new car.
Meanwhile, back in ye olden days of yore (like the 1960s-1970s) automobiles were considered to have about a 100,000-mile life. In the 1980s, "Built-in obsolescence" was a running joke about Japanese cars, which ran great then "blew up" at 100,000 miles, and Japanese cars had better reliability than US-made cars. (In 2012, New York Times declared "200,000 is the new 100,000" for care lifespans.) Teslas and other electric cars are well beyond that.
And what's a worthwhile range of cars? The world didn't avoid cars in the 20th Century, waiting for 21st Century cars with 200,000-mile lives. Some nations, some continents, embraced those short-lived cars of the 1920s, 1950s, and 1980s. And those cars accomplished what the owners asked of them: commuting, errands, professional work, etc.
Which is a point to consider: what do the owners need of electric cars?
For example, I was very close to getting a Chevy Volt. I was looking for a new car when US gas prices were hitting $4/gallon. It only had a 30- to 35-mile range on battery, but that easily covered my daily commute. Its gas engine handled the long distance driving I did on the weekends and alleviated any fears I had of battery exhaustion. If the battery was down to 85%, 75%, or even 50% of its original life at 100,000 miles, it'd still handle the daily driving I asked of it. Eventually, I caved in to a mid-life crisis and got a Charger, which is way more car than I really need but I'd gone through 25 years and 325,000 miles in sensible little cars.
Which is another point: what's worthwhile in a car? Skipping arguments that mass transit systems are all most people really need, all most people need in a car is not more than 10 or 20 horsepower; 100-200 miles range (less, if daily refuelings are possible); faster speeds than foot, bikes, or animal-drawn conveyances; a protective shell; and enough cargo capacity for their family and regular errands. You know, a VW Bug, Tata Nano, or Fiat 500. In that light, the popular electric cars today are as much gross overkill and salves for ego as an over-powered car like Dodge Charger. Getting 250 miles range, 100,000 miles battery life, and 100mph+ speeds from a Tesla is more than the minimum you ever need out of cars.
I used to wonder about the practicality of Teslas and Leafs and other modern electric vehicles, but I think they've proven themselves out well. Their lifespans are rivaling those of the cars I grew up with; the media is not filled with stories of distressed motorists stranded without a recharge; and their sales are better than any of the electric cars (e.g., EV-1) in the past.
With good, sustained sales and customer interest, car companies have the funds and justification to improve on batteries. Those battery packs are not stuck at current levels of performance. They're improving, and they have the funding to continue improving just like cars did in the 20th Century.
Mike Miller, Materials Engineer
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"Everbody's always in favor of saving Hitler's brain, but when you put it in the body of a great white shark, oh, suddenly you've gone too far." -- Professor Farnsworth, Futurama
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(01-19-2018, 10:11 AM)Rhea47 Wrote: Battery powered cars are slowly becoming more prevalent. But are they worth it due to the limited life of the battery? As well as the expensive battery replacement costs. I personally think that fuel cell technology would offer an better energy density. If all of the problems could be worked out of course. What do you all think?
I agree with you, for several reasons. First are the twin problems of range and recharging time. Even if range of an electric vehicle could be got to the same as that of an IC engined one, about 500 miles, the recharging time issue might well be problematic.
Second is the problem, not often discussed, of the expense of tooling up for electric vehicles. Both the charging stations themselves and the extra power generation and transmission capacity required.
Third is the fact that the batteries weigh a good part of a ton, which has to affect efficiency.
Fourth is the hazard caused by high energy density batteries in a crash.
Fuel cells don't have any of these problems. For some types of fuel cells (methanol for example) existing fuel delivery infrastructure could be used. Fuel cells are lighter than IC engines, if anything. And recharging is as simple as filling a tank with liquid. And the fuel itself is reasonably safe, if the right one is chosen. Methanol probably - liquid hydrogen, not so much.
BTW, the idea of fuel cells is often rubbished because, of course, if it's worth doing for ecological reasons the fuel has to be made. The solution to that is simple; use spare power, when the network is under light load otherwise - maybe at night.
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(01-20-2018, 08:21 PM)iancampbell Wrote: I agree with you, for several reasons. First are the twin problems of range and recharging time. Even if range of an electric vehicle could be got to the same as that of an IC engined one, about 500 miles, the recharging time issue might well be problematic.
Tesla supercharger can add another 270km of range in 30 minutes. A full charge to over 400km takes an hour and 15. I realise that the US has different driving habits than Europe but how often does anyone drive more than 400km in a day? Beyond that how many drive more than 670km and wouldn’t take a 30 minute break? Or an 800km journey with an hour’s break?
(01-20-2018, 08:21 PM)iancampbell Wrote: Second is the problem, not often discussed, of the expense of tooling up for electric vehicles. Both the charging stations themselves and the extra power generation and transmission capacity required.
I’ve seen that discussed frequently but where I live electric charging stations have been steadily increasing in number for years (there are two on my street and the last few motor way service stations I’ve been to have had ranks of them, they’re becoming common in supermarket carparks too). The cost isn’t a dealbreaker.
(01-20-2018, 08:21 PM)iancampbell Wrote: Third is the fact that the batteries weigh a good part of a ton, which has to affect efficiency.
The weight and volume of the batteries certainly do however the gains made elsewhere is what complies like Tesla are banking on:
https://youtu.be/oJ8Cf0vWmxE
(01-20-2018, 08:21 PM)iancampbell Wrote: Fourth is the hazard caused by high energy density batteries in a crash.
Is there any reason that would be worse than a tank full of fuel?
(01-20-2018, 08:21 PM)iancampbell Wrote: Fuel cells don't have any of these problems. For some types of fuel cells (methanol for example) existing fuel delivery infrastructure could be used. Fuel cells are lighter than IC engines, if anything. And recharging is as simple as filling a tank with liquid. And the fuel itself is reasonably safe, if the right one is chosen. Methanol probably - liquid hydrogen, not so much.
BTW, the idea of fuel cells is often rubbished because, of course, if it's worth doing for ecological reasons the fuel has to be made. The solution to that is simple; use spare power, when the network is under light load otherwise - maybe at night.
It seems like the primary reason fuel cells are still a pipe dream for anything more than prototype commercial vehicles is that no one has figured out a way of making them economically. This issue is what has driven the electric car market in recent years; decreasing manufacturing costs. Is there anything like that on the horizon for fuel cells?
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01-21-2018, 12:16 AM
(This post was last modified: 01-21-2018, 01:58 AM by stevebowers.)
I like fuel cells because they utilise oxygen from the atmosphere; this allows them (in theory) to have a greater energy density than batteries.
They don't deliver this energy very quickly, though, which means that capacitors (and supercapacitors) are better if you need a lot of power quickly.
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01-21-2018, 01:26 AM
(This post was last modified: 01-21-2018, 01:59 AM by stevebowers.)
(01-21-2018, 12:16 AM)stevebowers Wrote: I like fuel cells because they utilise oxygen from the atmosphere; this allows them (in theory) to have a greater energy density than batteries.
They don't deliver this energy very quickly, though, which means that capacitors (and supercapacitors) are better if you need a lot of power quickly.
Yup. However, I don't see any reason why a supercapacitor bank shouldn't be used in combination with another type of energy storage/generation, maybe fuel cells, for times when short bursts of power are needed.
Another reason for having some sort of energy storage on board is to allow regenerative braking to be used. Braking wastes all the energy used to accelerate the vehicle; regenerative braking allows at least some of this energy to be recovered.
As for the comparison between a tank of fuel and a battery bank: A damaged battery bank is quite likely to get hot without any interaction with the outside, simply by shortcircuiting - and current designs use lithium, which is highly flammable in air to say the least. Whereas something like methanol doesn't just spontaneously combust and water-miscible fuels (including methanol) are easy to get rid of with simple water. Try stopping a lithium battery fire with water!
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01-21-2018, 02:06 AM
(This post was last modified: 01-21-2018, 02:06 AM by stevebowers.)
Supercapacitors are used by electric buses and trams that can recharge quickly and frequently at traffic stops.
https://en.wikipedia.org/wiki/Capa_vehicle
Autocars, drones, transporters, vecs and robots would use supercapacitors in a similar way - if they could gather electrical power frequently from their environment, they would have access to a much greater power density at any one time (compared to devices using batteries or fuel cells). On the other hand a car, drone, transporter, vec or robot that needed to store a lot of energy for a long time would be better off using fuel cells or some kind of battery.
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(01-21-2018, 02:06 AM)stevebowers Wrote: Supercapacitors are used by electric buses and trams that can recharge quickly and frequently at traffic stops.
https://en.wikipedia.org/wiki/Capa_vehicle
Autocars, drones, transporters, vecs and robots would use supercapacitors in a similar way - if they could gather electrical power frequently from their environment, they would have access to a much greater power density at any one time (compared to devices using batteries or fuel cells). On the other hand a car, drone, transporter, vec or robot that needed to store a lot of energy for a long time would be better off using fuel cells or some kind of battery.
I suspect that the design of vehicles in (say) 2050 won't be all that simple. Storage of small amounts of electricity may well be necessary on top of the main engines - for heating up the reaction cells in a fuel cell, for example. It's worth noting that a present-day non-hybrid car holds enough energy in the battery to travel a couple of hundred metres, which is occasionally useful - but the reason for the energy storage is specifically to start up the main engine.
Also, some high-performance hybrids rely mostly on their IC engines and only use the electric power boost for short surges of power; I believe that the latest hybrid BMW does that.
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