Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
×

Comment Re:Either way the tech needs another 15-20 years (Score 1) 659

Battery tech needs to go up in power density at least an order of magnitude

That seems an exaggeration. I have a Honda Fit EV that will go about 105 miles on a charge (best case). I have a Subaru STi that goes 250 miles on a fillup. There are electric vehicles that have smaller and larger ranges, and the same is true for gas powered cars, but I don't think we need an order of magnitude improvement in battery capacity in order to be useful to the majority of people. The Fit EV is a lease (it's a compliance car) but my plan when the lease ends is to get a Tesla Model-E with 200 miles of range. Based on my experience with the Honda, 200 miles of range should be enough for all but a couple trips a year that I do.

With the Honda, I use about 50% of a charge on my 55 mile commute. It takes about 90 minutes to recharge that when I get home, i.e. I can commute to work and back home again, grab a bite to eat and have nearly a full charge before I'm ready to go back out that night. This is all without public charging infrastructure!

I think that when people talk about wanting to recharge their EV in the same time it takes to fill a gas tank, they're missing the point that the refueling of the two vehicles would typically be different, specifically that cars tend to sit for long parts of the day and installing a recharging network that can be used (say, while you are at work) is not an insurmountable barrier.

Long trips are indeed the one case that the EV struggles with, but I think that Tesla et al will come up with reasonable ways to deal with this, whether it be superchargers or towed battery packs

I maintain my gas car for just such trips, and I find that when I'm commuting daily with the EV, the gas car only gets run once or twice a month (seldom enough that I've had problems with the brakes rusting so that it's difficult to get the vehicle to move).

Comment Re:They made a decision that's easier for them. (Score 1) 659

I have to question whether this is really the Toyota plan, or whether Hydrogen is a delaying tactic to be able to continue shipping their ICE cars, which let's face it, they have a large investment in. My gut tells me that Hydrogen powered cars in large numbers is decades away. If I'm right, why would Toyota be jumping on a technology that isn't likely to be useful anytime in the near future when we have a technology (BEV) that is already sufficient for a large number of people (the technology is, perhaps the price point isn't there yet) and it's a technology that is almost certainly going to greatly improve during the time frame necessary to bring Hydrogen automobiles to market.

Comment Re:Hydrogen Vs Batteries (Score 1) 659

I've read that the grid is already capable of charging large numbers of EV cars. For instance: http://cleantechnica.com/2014/...

Also, if the electric company offers off-peak discounts, people would almost certainly take advantage (my Honda Fit EV, and most if not all of the other major EVs can be programmed to charge at a specific time, i.e. I just enter into my smartphone when I want the car to charge and it will then delay charging until that time. You can force it to charge immediately if you think you'll need to use the car again that day before normal charging time).

Comment Re:Electric. (Score 1) 659

I'm leasing a Honda Fit EV which has a quoted range of something like 84, but when not using heating systems during the winter I see about 105 miles per charge (which costs about $2.50 in electricity). Interestingly, if you encounter a traffic jam in an electric car your range tends to go up because higher speed causes higher drag and a loss of efficiency; the EV car loves low speed driving. It's only a 19 kWh battery, so it would be relatively easy for Honda to produce one with more range (and I think Tesla has the right amount of range). There are enough chargers that there is little chance of getting stuck, but it would be a pain to have to plug in and wait, so typically I would only charge near my destination (like, if I'm going shopping and the mall has a charging station). The charging station issue is fairly easily solved - certainly there are no technical hurdles to greatly increasing the number of chargers out there - there simply needs to be a large enough user base to justify adding more. The fact is, however, that it's very rare that I charge away from home. Most of the time the range is sufficient for all the driving I do in a day, and I can simply plug in at home. I have a dryer outlet installed in my garage so that I can recharge at the end of a typical day in about 90 minutes (about 50% of the capacity is pretty typical when I get home from my 55 mile commute).
I've already decided that my next car will be a Tesla Model-E (200 mile range in a beemer 300 style chassis). I would guess that with that range, I might have to rent a car a couple times a year for long trips...

Comment Re:Oh noes, I can't drive X miles (Score 1) 398

I commute about 2 miles to and from work each day.

But the Leaf is ugly, the Tesla S is expensive and neither is convertible.

I agree about the Leaf - I'd buy one if they weren't so darn ugly. I'm currently leasing a Honda Fit EV and love it My commute is 48 miles round trip and it can do that twice before recharging (but obviously I just charge it every night when I get home). Biggest drawback so far has been wintertime in Boston - the range drops by 50% when you have to run the heat (so I just drive my Subaru instead).

Comment Re:Somewhat cheaper... (Score 1) 496

You have a good point, but there could be an advantage to your night vision with the camera - since you can limit how much light the screen emits, you won't be blinded by the reflection of someone's headlights But as someone else mentioned, it's important for the screen to properly dim (which seems to be something that eludes manufacturers).

Comment Re:Uh... anyone check electric grid capacity? (Score 1) 327

Yeah, even as I was writing that, my little voice was telling me something was wrong :-)

The estimator I used (which takes geographic location into account) mentions 4.28 kWh/m2/day which is where I got my original number. I see that it also mentions 158 sq-ft as the roof area needed. I think that's the entire roof of my house 3 layers deep ;-)

Comment Re:There is no Magic Energy Fairy (Score 1) 327

I agree that the lease makes it harder to compare to other cars. Honda only offers lease of the FIT EV at this time, but I also liked it because it was a risk reducer for me - worries about battery life etc. I have used the air conditioning and it makes a surprisingly small impact on milage - I saw a loss of less than 1 mile /kWh. The heater on the other hand really uses a LOT of battery. I'm going to be interested to see what happens when it gets really cold here in the winter.

The 90 minute charging time is to re-charge after my 10 kWh commute. If I was to run the battery flat, it's more like 3 hours. I've only done that twice in 6 months of driving... I think the 20 minute charging time is with a special DC charger. I think they charge at 400+ volts (Honda doesn't have this, but I think the new Nissan Leaf does). Mine uses a modified dryer outlet for 220 volt charging. Charging at 110 volts is not practical. It takes all night to charge at 110 volts. It's definitely an emergency thing (Honda supplies a 110 volt charging cable that is carried in the cargo area, but if you had to use it I think you would plug in and come back for the car the next day!)

I have no doubt that purchase price for an electric is higher than that of a gas car, although one could probably make a case that the Tesla is comparably priced to similar luxury vehicles. Certainly if I could buy a Honda FIT EV it would cost substantially more than the gas version. TCO I'm not so sure about. There is the savings in fuel which isn't huge but adds up over the years. The maintenance is probably unknown, but looking at the systems of the FIT, there's a LOT less to maintain than in an ICE car. I think chances are good that maintenance will be substantially less (certainly you'll save on brakes - probably never replace them for the life of the car!).

Tax break - Honda took the $7,500 tax break, not me (because it's a lease) :-(

Where do you live and how long is your commute? You sound like you don't think you could rely on an EV car...

Comment Re:Electric cars are *not* more energy efficient (Score 1) 327

I think Honda is being very conservative because of the bad press it would generate if people were ending up at the side of the road with no charge left. Interestingly, if you *do* run out of charge they'll send a flatbed truck to come get you. My guess is that if you do that more than once or twice they cancel the lease!

As for efficiency, I think one of us made a math error. I got:
Diesel #2/ US gallon: 146,300 kJ converted to Imperial Gallons = 175,560 kJ/gal imp.
If you get 60 mpg, 175,560kJ / 60 = 2,926 kJ/mile == 4,681 kJ/km == 1.3 kWh/km
(http://www.extension.iastate.edu/agdm/wholefarm/pdf/c6-87.pdf pdf alert)
Simpler way to look at it:

Diesel US gallon = 138700 BTU * 1.2 (imp gal) = 166440 BTU = 48 kWh. 60miles / 48kWh = 1.25 miles / kWh
So, based on that even the Tesla @ 3.5 is twice as efficient as the diesel and the FIT is up to 5 times as efficient.

Did I miss something?

Comment Re:Uh... anyone check electric grid capacity? (Score 1) 327

6.5 is an optimal milage, 4.5 is a pretty typical number with passengers and/or cargo. Air conditioning doesn't seem to cost that much in milage, heating does - I expect my winter numbers to be lower. Interestingly, I get better milage when I hit traffic jams! (lower speeds, thus lower air drag).

Actually, in another post I did a calculation on PV - it looks like here in Boston (not the solar capital of the world) it would take about 4 square meters of PV to generate enough electricity for my daily commute).

Comment Re:There is no Magic Energy Fairy (Score 1) 327

Respectfully, although you say you are all for electric cars, you then go on to imply that there is a long way to go before they can be practical. I'd say there is a short way for them to be practical for a large (but not 100%) of the populace.

I'll relate my experience of the last 6 months of leasing a Honda FIT EV:

I drive about a 50 mile round trip commute daily. The Honda gets between 4 and 6.5 miles/kWh on that commute - it'll be worse in the winter, but most days I get home having used about 10 kWh for the commute (thats under 1/2 a charge - I forgot to recharge one night and was able to do the commute the next day and still make it home with 10-15 miles of range left). It takes about 90 minutes after I plug in to recharge to 100% charged. Future charger technology will no doubt shorten that, but I've never had to take the gas car because the electric car hasn't finished charging. I think I pay about 0.18 / kWh for electricity here in Massachusetts, so it costs me about $2.00 for the commute versus about $5 for my Subaru (which is a much less efficient car, so I don't want to imply that's apples for apples).

If I have the math right, here in Massachusetts I could install about 4^2 meters of PV array and generate enough electricity to cover the commute. I based this on a solar system estimator at http://www.find-solar.org/index.php
While you can make cases that it costs CO2 to produce the PV cells etc., as other people have mentioned you also pay CO2 costs to deliver gas to the station, but it's not unreasonable that a large percentage of drivers that own electric cars could produce enough electricity to power their vehicles for their daily drives.

As for costs, I lease the car from Honda for $275/month. I'm saving about $100/month on fuel although again that's comparing an efficient Honda to a STi Subaru play car (22 mpg) so it's not a perfect comparison. Still, in my case, my net cost is about $175/month or just over $2,000 per year to lease the car. So, not at all an extravagant car like the Tesla. I would say affordable by many people if not all (hard to beat a $12,000 gas Honda).

As for usage, I expected that I would drive the Honda on the daily commute but that a lot of weekend running around would require me to use the Subaru. The reality has surprised me: The Subaru has been used more like once per month. It turns out that most of the drives that I thought would require the gas car can be done if I plan on recharging at a public recharge station, which usually isn't that difficult.

The two comments I would say about range (anxiety) is that you have to plan your driving. (I'm a pilot, so it's a lot like planning my flight - you need to leave the house having a fairly good idea of where you'll be going that day, and if it's a longer than 100 mile day which charger you'll use to recharge). This isn't as bad as it sounds, because for a lot of us, our days don't change that radically. I can do the commute to work and still have about 70 extra miles available for appointments and errand running without having to recharge. If your daily commute is more like 100 miles, this probably won't work for you unless there is a recharging station at work. If not, a gas car is probably still for you.

The second comment is that fast driving really really kills range. At 55 I get about 4.4 miles per kWh which gives me about 100 miles of range. At speeds above 65 this starts to drop off quickly. At 85 mph I couldn't make it to work and back. The funny thing is that I tend to take back roads (and thus get around 6.5 miles per kWh giving me around 120 miles of range, and yet this only costs me an extra 10 minutes of commute because although sections of the highway are pretty fast, other sections are really slow because of traffic. Driving back roads I'm moving more slowly, but at a much more steady pace so it doesn't take that much longer to go at a speed that really conserves power. Also, it's a much more pleasant drive! That said, it probably wouldn't be very good for portions of the country like out west where you need to drive at 75+ speeds because of the distances involved.

I went on much longer than I meant to, but I find this BEV a very viable replacement for a gas car, especially in a two car family where there is still a gas car available for longer trips, but even without that I think it would be viable by renting a car occasionally when longer trips are required.

As for your statement that it would be beautiful to drive a quiet car with electrical motor performance, yeah, it is! I can out-accelerate most of the smaller cars on the road, and on a back road (where wind noise is minimal) I can whisper in the front seat and the other people in the car can hear me!

So, to recap, I'd say that cars like the Nissan Leaf, the Honda FIT EV, the Chevy Spark, are actually viable electric cars today and not play-toys for the rich. I think the battery technology will continue to improve, but it's actually already good enough for a lot of us.

Comment Re:Electric cars are *not* more energy efficient (Score 1) 327

I'd like to note that using the Tesla for milage figures is akin to using a SUV for gasoline milage figures - the Model S is a large heavy car. My Honda FIT EV gets about 25%- 80% better mileage / kWh. (I get between 4.5 and 6.5 miles per kWh versus the 3.5 you quoted for the Tesla [130+reserve on 19kWh battery] - I'd expect numbers to improve in the next few years as EV production by the large auto makers is still in it's infancy).

Slashdot Top Deals

It's time to boot, do your boot ROMs know where your disk controllers are?

Working...