Posted by Max Dunn
Wed, 09 Jan 2008 18:39:28 GMT | no comments
An revolutionary new technology is being developed by Stanford researcher Yi Cui that could could generate 10 times more energy from lithium-ion batteries. The trick is that instead of using carbon anodes, they use silicon nanowires because silicon can hold large amounts of lithium atoms. The nanowire technology allows these small wires to swell to four times their normal size without breaking. [1]
When Cui’s paper was originally submitted six months ago, they had only achieved 30 charge-discharge cycles. Since that time however, Cui’s team has pushed the battery through 1000 cycles. [2]
Ultimately, these batteries should be cheap to build. However, they are probably 5 years away from being commercialized. [3]
In reality though, the “10 times more energy” figure is just the theoretical charge capacity increase in the silicon anode, so a real production battery won’t see that much improvement. But even if it improves the overall energy density of a lithium ion battery by 2 or 3 times, that would still be very significant.
[1] Nanowire battery can hold 10 times the charge of existing lithium-ion battery
[2] New Nanowire Battery Life Reaches From iPods to Electric Cars
[3] GM-Volt.com: Interview with Dr. Cui, Inventor of Silicon Nanowire Lithium-ion Battery Breakthrough
Posted in Electric Vehicles, Global Warming, Peak Oil
Posted by Max Dunn
Sun, 30 Dec 2007 17:43:32 GMT | 1 comment
When I talk about how clean electric vehicles are, people sometimes ask if they really do reduce greenhouse gases since burning coal to produce electricity creates a lot of CO2. My standard answer to this question is that even in the worst case, electric cars are twice as clean as gas powered cars. However, while reading an article in Forbes about vehicle-to-grid (V2G) systems. I realized that in general, electric cars are much cleaner than even this.
This article had an interesting chart that said electric cars produce about 1.1 tons of greenhouse gases a year while gas powered cars produce 6.3 tons – over 6 times more! Let’s see if we can verify these numbers.
The average car is driven 15,000 miles per year and electric vehicles normally get 4 miles per kWh, so it takes about 3,750 kWh of electricity a year to power an electric car. In California, the mix of electricity production produces about 0.6 lbs of greenhouse gases per kWh so this would produce 2,250 pounds, or 1.1 tons of greenhouse gases – right on the money with the Forbes chart.
A gas car, on the other hand, produces about 1 lb of CO2 for every mile driven (based on producing 20 lbs per gallon and getting 20 mpg). So 15,000 miles would produce 15,000 lbs of greenhouse gases, or about 7.5 tons – which is more than the Forbes estimate of 6.3 tons (maybe they are using a higher mpg).
So electric cars are even cleaner than I had thought, producing about one sixth as much greenhouse gases as a gas car.
Posted in Electric Vehicles, Global Warming, Peak Oil
Posted by Max Dunn
Tue, 04 Dec 2007 17:15:19 GMT | 2 comments
That is the question – whether to buy a low-speed electric vehicle now, or wait for a high-speed electric vehicle later? Here are the factors I am looking at:
- What type of transportation do I need?
- When will high-speed electric vehicles really arrive?
- How much will they actually cost?
- When will the severe oil shortages start?
- Will there be subsidies for electric vehicles?
The short answer is that I am going to buy a low-speed NEV now and wait for later to buy a freeway capable electric car. Here is the long answer:
Read more...
Posted in Electric Vehicles, Global Warming, Peak Oil
Posted by Max Dunn
Wed, 12 Sep 2007 20:31:35 GMT | 3 comments
Today, I went grocery shopping on our electric Zapino. I was a little worried that I wouldn’t be able to fit all the groceries in the basket and under the seat, so I took a Trader Joe’s bag too and planned to hold it between my feet. However, it turned out that I didn’t have any problems. Here is what I bought:
- Large powdered Gatorade
- 2 – Boxes of cereal
- Half gallon milk
- Quart of goat’s milk
- Jar of mayonnaise
- 2 – Tamales
- Frozen fish
- Asparagus
- French rolls
As you can see from the pictures, they all fit in nicely! I definitely could have squeezed a few more things in, and then could have filled up the shopping bag and put it between my feet.
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 02 Sep 2007 15:37:48 GMT | 5 comments
After running the Zapino battery all the way down last night, I put the charger on it with the Kill-A-Watt meter to record how much power it would take to recharge. The charging rate started at about 360 watts and then increased to 400 watts. The total power consumed was 2.68kWh.
This is an interesting number and does make sense since the battery pack is rated at 2.28kWh (60v-38ah) and you would expect that there are some losses when charging. Sealed lead-acid batteries typically can be up to 95% efficient and chargers are typically 90% efficient, so combined these numbers lead to the total efficiency we measured of 85%.
Another useful fact about charging is that for every hour that the scooter is being charged, you are adding about 4 miles to the range. (Based on the charger putting out 400 watts, and the Zapino using about 100 wh/mile.) So, for instance, my wife works part time at an office about 18 miles away. So if she is there for 4 1/2 hours, the Zapino will be completely recharged.
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 02 Sep 2007 02:06:40 GMT | no comments
After the excursion with my wife today where we traveled about 20 miles, I went to go pickup my son at the pool which was a little over 5 miles away. I was still taking it easy in economy mode and staying around 25 mph. However, I did go through the neighborhood where there were a lot of stop signs. Coming back home, we got about 3 miles away and the range indicator starting to drop into the yellow when we accelerated. At 2 miles it was dropping into the red, so I started driving 15-20 mph. At about 1 mile away, the engine cut out because the indicator dropped below the road while accelerating. Coasting to a stop, I turned off the key and back on again and was able to continue. I then starting going really slowly, about 10 mph. The engine cut out a few more times, but we made it home. So i consider that we fully utilized all the available range.
Total distance today 31.2 miles. Not bad!
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 02 Sep 2007 00:21:38 GMT | 3 comments
Last Wednesday, after weeks of looking around at electric scooters, we finally bought a Zapino and love it! Today, Suzanne and I took a little excursion around town to see if it could carry both of us and to see how the battery would hold up on a longer trip.
The first thing you should know is that it was hot in San Jose today, getting up to 94 degrees. Riding the Zapino was nice because the breeze cooled us off. However, we were worried that it would overheat because we were pushing its 282 lb weight limit with our combined weight of 275lbs. (And no, Suzanne forbids me to break out our weights separately. ;-)
Since we were just out cruising, we were using the energy saving mode which limits the top speed to 30mph. Most of the time, this is plenty fast, but I did kick it into high-speed mode several times going down Highway 9 to Los Gatos.
The Diagnosis light was flashing its 2-3 combination which means that it is overheating, but I just ignored it and kept going
We stopped at a store and looked around for about 5 minutes. When we got back on the Zapino, the overheat protection kicked in and it made us go really slow. This was probably because after stopping, there was no more wind to cool off the controller and it was so hot out anyways. This slow speed was fine since we only needed to ride a block. We then got off again and walked around for about 20 minutes before getting back on the scooter, at which time it had cooled down.
Going home, we continued to take it easy but the “overheating” warning starting flashing again very soon. This didn’t seem to make any difference, although our top speed was a little lower, around 25 mph in the energy saving mode. Just for fun, right before we got home I put it back into high-speed mode and it sped right up past 30 mph, no problem.
I realized on this trip that the diagnosis light is a little annoying. In order to read the flashing codes, you have to look at it continuously for about 5 seconds, which is very dangerous while driving.
Our total outing ended being about 20 miles and the charge indicator was only about halfway down in the green. So we have now confirmed that driving conservatively with a heavily loaded bike can take you at least 20 miles on the Zapino.
Suzanne and I really enjoyed our little excursion on the the Zapino!
Posted in Electric Vehicles