Posted by Max Dunn Sat, 31 May 2008 23:30:07 GMT | no comments
Which do you think provides more performance by weight and size – a gas motor or an electric motor?
You are right if you said an electric motor. Here is a picture of an electric motor that provides twice the performance of the gas motor, yet is much smaller and has only 1 moving part!
(Reference: EVDrive BMW Project)
Posted by Max Dunn Fri, 30 May 2008 04:10:09 GMT | no comments
There was an interesting talk at the Woods Energy Seminar at Stanford yesterday by Dr. Gavin Conibeer about 3rd generation photovoltaic (PV) devices.
The 1st generation are the PV cells we have now that cost around $6/watt and are around 20% efficient. The 2nd generation are the thin film cells which cost around $1/watt but are only about 12% efficient. The 3rd generation cells will use quantum dot technology created using thin-film manufacturing methods, so they will be a lot less expensive than 1st generation devices but will also use a variety of techniques to boost efficiencies up to 65% which will drive the cost down to $0.20/watt.
This sounds pretty great! However, the catch is that when asked when these 3rd generation PV cells would start going into production, his answer was “It is still a long ways away.”
Following are the notes I took during his talk:
Posted by Max Dunn Wed, 28 May 2008 19:47:27 GMT | no comments
All of the major electricity generating systems in use today have a fairly steady output. Whether they are powered by nuclear, coal, hydro or natural gas, the electricity output will be fairly constant unless there is a malfunction. However, solar and wind systems aren’t consistent – clouds can dramatically affect the output of solar systems, and lulls and gusts can affect wind systems.
In our electrical grid, it is important that the supply of electricity consistently matches its demand. This will become more challenging once solar and wind systems are producing a larger percentage of the total electrical power, and there are currently no good ways to smooth out these fast fluctuations. Spreading the solar and wind units far apart helps so that clouds and gusts won’t affect all the units at the same time. Also pumped hydro (where water can be pumped up into a dam using electricity as well as letting it out to produce electricity) can help smooth things out as well as using natural gas spinning reserves.
However, we will still need more regulation that is much faster than these, and this is where Vehicle-to-Grid can help. If we can reach a level where a significant amount of electric vehicles are hooked up to the grid with fast command communication, they will be able to quickly smooth out the electrical surges and lulls from solar and wind systems. Otherwise, we will likely run into severe regulations problems with these systems due to clouds and gusts.
Posted by Max Dunn Wed, 28 May 2008 15:47:59 GMT | no comments
There certainly a lot of excitement over electric cars these days. A 2001 Toyota RAV4-EV with over 47,000 miles sold on eBay for almost $70,000! (The selling price listed was $89,000 but this was an illegally retracted bid and the seller confirmed that it was sold for $69,850.)
It was in good shape with only minor scuffing on the left bumper and had an HOV stickers so it can drive in the car pool lane, but $70k seems like a lot of money for an electric car with almost 50,000 miles. Hopefully next year we will start seeing brand new electric cars closer to $40,000.
If you still are dying to get one, there is another RAV4-EV for sale on eBay and the bidding is currently at $50,000.
Posted by Max Dunn Tue, 27 May 2008 18:00:55 GMT | 7 comments
Here is an interesting thought experiment: how would our lives change if gas cost $100 per gallon?
Posted by Max Dunn Sat, 24 May 2008 02:12:51 GMT | no comments
As we have seem, the biggest per mile cost of running an electric vehicle is not the electricity, it is the battery depletion. So it is important to maximize the life of your batteries. One trick that works with all battery techologies is to take short trips and recharge after each one. By minimizing your depth of discharge (DOD) you will maximize the total energy that the batteries will deliver over their life.
Another very important factor is to charge the batteries correctly. Especially for sealed lead-acid batteries like gel or AGM, correct charging is critical. Deka states that if their batteries are continuously charged with a voltage that is only 0.70 volts over the proper charging voltage, it will reduce the battery life by 60 percent! This is because if sealed batteries are overcharged, they will dry out and there is no way to replace the lost moisture. It is likely that all sealed lead-acid batteries will suffer from this, not just Deka batteries.
Here is the kicker: the proper charging voltage varies depending on the temperature. It ranges from 15.10 volts when it is below 40 degrees 13.60 volts when it is above 120 degrees. And it is not good enough to just measure the air temperature, instead it is important to measure the temperature of each battery since they will often be warmer than the outside air.
So unless your charger or BMS has a temperature probe on each battery, it is almost guaranteed that the batteries are not being charged correctly and that their potential life span will be reduced.
Posted by Max Dunn Wed, 21 May 2008 18:29:07 GMT | no comments
BlueSky Motors in Sacramento periodically sells EV Ford Rangers on eBay.
When I contacted them about the reserve price for a previous EV Ranger, here is what they said:
The reserve on the vehicle is $26,998 + License, Calif. sales tax, doc fee, and registration. The total cost with a PSC charger ($600.00) ends up close to $29,000. You can call for a test drive – (916) 929-7508 ask for Scott.
Paying almost $30,000 for a Ford Ranger seems pretty expensive – is there a way to justify this? One way is to think about the extra cost as just “pre-paying” for your gas.
The gas 1999 Ford Ranger gets a combined mileage of 16 MPG, so this is about $0.25 per mile at $4 per gallon. Assuming electricity will cost $0.05 per mile, you will save $0.20 per mile with the EV Ranger. (The EV Rangers NiMH batteries will likely last for the life of the car, or about 150,000 miles, so you don’t need to worry about battery replacement costs.)
So one way of looking at the extra $20,000 that this EV Ford Ranger costs is that you are just pre-paying for gasoline at $4 per gallon for the next 100,000 miles and after that, it is like getting free gas. And when gas goes up to $6 a gallon or more, this will seem like a real bargain!
Posted by Max Dunn Mon, 19 May 2008 16:04:49 GMT | no comments
When driving an electric vehicle (EV), it is important to know how far you can go on a full charge. On flat ground, the range will be pretty consistent and the only variable will be if you are driving around town or on the freeway. But how will your range be affected when you are driving up a hill?
This is an important question to me because I like to go surfing in Santa Cruz which is about 30 miles away and requires a climb of 1500 feet over a mountain range.
As a rule of thumb, you can add 10 miles for every 1000 feet you climb. So to take the Santa Cruz example, the peak is 15 miles away and a climb of 1500 feet, so it would actually take 30 miles of energy to get to the peak.
Going downhill of course, won’t take as much energy and will actually add some energy if you have regenerative braking. So the total trip to Santa Cruz is likely to take about 37 miles worth of energy.
RAV4 owners have reported that it takes less energy to climb a hill, only 6 miles per 1000 feet. One owner reported driving to Mt. Baldy which was 20 miles away and a climb of 6000 feet. He used about 60 miles worth of charge to get to the top. However, coming back down he added 20 miles of charge, so the round trip only took 40 miles of charge, or only the linear distance disregarding the climb. Ref
Bottom line is that while you need to be aware that it takes extra energy to climb hills, EVs can handle them with no problem.
Posted by Max Dunn Wed, 14 May 2008 18:21:05 GMT | 6 comments
While Altairno batteries have demonstrated 25,000 cycles, my Zapino batteries are starting to weaken after less than 500 shallow cycles.
This was evident in a ride I took today to Los Gatos to get a new battery for my MacBook. (Yes, even the lithium-ion battery in my MacBook gave out after less than 300 cycles! But this was likely just a manufacturing problem, not an inherent limitation.)
I knew the Electier batteries in my Zapino batteries were getting weak, so I rode in the “economy” mode the whole way, accelerated slowly and rode 25 MPH or less. There were some small hills but I took it really easy going up them. Nonetheless, by the time I was approaching home, the needle was dipping into the yellow upon acceleration and even starting to get in the red. The entire ride was 14 miles, and I probably could have nursed it another 3 to 5 miles, but this was still only about half of the 30 mile range that we got when the Zapino was new.
Posted by Max Dunn Tue, 13 May 2008 02:01:13 GMT | no comments
The electricity to power an electric vehicle costs very little – usually around 3c per mile. A bigger cost is the wear-and-tear on the batteries, which will cost 8c a mile or more.
For instance, if an electric car has a range of 75 miles with a 25kWh lithium-ion battery pack that has a life of 2,000 cycles, then the car could go 150,000 miles on the battery pack. If the batteries cost $25,000, this adds about 17c per mile to the cost of operating the car in addition to the electricity.
But what if the batteries lasted longer – much longer? Then the total cost per mile would be a lot lower.
For instance, lets say that instead of 2,000 cycles you could get 25,000 cycles out of the batteries. Maybe these batteries cost twice as much, but this would still bring the cost per mile down to about 3c per mile.
Well it appears that Altairnano might have done this. In their recently released 2007 annual report, it states that in January 2007 they completed 25,000 deep charge/discharge cycles of their batteries and they still retained over 80% of their original charge capacity.
The batteries are not cheap – it appears they are selling them for about $2,000 per kWh, about twice what other lithium-ion batteries sell for. But if they can really go 25,000 cycles in the field, it will be an exciting breakthrough!