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Zhukova
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What I meant was that people will drive 40 miles each day and recharge at night. So for a 300 mile battery, the discharge is only 13%.
So .4 kwh/kg x 4 miles/kwh = 1.6 miles/kg. 300 miles would need about 187 kg. But this gives 10kw/kg x 187 kg = 1870 kw or 2,500 hp, more than matching the power of engine-driven systems.
@mahonj I think batteries for BEVs will always be sized for range. When they are cheap and small enough, people will want whatever gives them 300 miles range. But they will drive only 40 miles for 360 days out of the year. Just about every article on new batteries describes capacity lifetime in terms of deep discharge, but practical use will be different.
On-site PV. You mean a PV array that can put out 20kwh/day (with full sunlight), which would be about 15x15 meter array? Creating hydrogen like that for a car doesn't seem very practical. Probably the PV array wouldn't be backed-up, it would be supplemented by the grid most of the time because there's not enough space or sun to put the array.
No details about how the hydrogen will be created or transported. These problems have been studied with great intensity by governments and industries. The fact that Sandia needs to study it again means that practical solutions are still a fantasy.
30 kW/kg is great! I keep waiting for Li-Air battery to be perfected, but they seem to be plagued by low current density. So you need a 400 kg battery to get 100 hp, but 1,200 mile range. RPI's 600 wh/kg and 30kw/kg in a 100 kg battery would allow a BEV with about 250 miles range and 4000 hp!
"One major cell phone manufacturer has already expressed interest in the system, according to the TUM team. " If the cell phone makers can do this, measuring the position of a cell phone to a few centimeters, then they could also disable the cell phone in a driver's hand.
Or long platoon of 20 semi trucks, six feet behind each other, hogging the right lane. How is that going to work?
"where they can join and leave platoons" How about where manually-driven cars can bust through a 20 car platoon hogging the right lane, when it needs to get off on an exit ramp?
It's not to surprising that a battery of $150 is available. But the 250 Wh/kg capacity is "not there yet". For a BEV, people need much more range. At 4 miles per kwh, you need about 50 kwh battery for a respectable 200 miles. But that's a big battery - 200 kg (440 lb) and still costs a lot, if you want good range. I think Envia's battery is "proven' because GM engineers say it has 400 Wh/kg ( 125 kg or 275 lb/50kwh), but the lifetime is a little less than advertised. I don't know how the weight affects milage, but I still think they are testing it for deep discharge. Anyway, the Envia problem is more about who stole the anode formula. They are using Argonne Lab's cathode, but the silicon composite anode is what the law suit is about and when that's settled, another battery maker will already have a similar anode on the market. What's the advantage of 5,000 cycles over 1,000? Tesla is pushing long-range vehicles, which means a big battery. This means most of the time the battery is being discharged only 20% and recharged every night. The 1,000 cycle battery on 20% DOD would have a practical lifetime of about 20,000 cycles / 365 = 54 years! But the 5,000 cycle battery on 20% DOD would have a real lifetime of about 100,000 cycles / 365 = 274 years! I don't see a practical advantage of 5,000 cycles for a long-range BEV.
...and the copyright lawsuits against Envia don't help them much.
One more item about the Envia battery. Their web site shows 400 cycle lifetime at 80% DOD. But they don't have any info about lifetime at 20%DOD. In addition, it seems obvious that GM is testing at deep discharge in a small battery designed to have high current output. The high current per kg also degrades the lifetime. So if they test a 200 mile battery, as designed for BEV, instead of a short-range battery designed for the Volt, the average current draw would be much smaller. Therefore, the lower current and the small DOD would extend the battery lifetime very much. I wouldn't give up on Emvia's battery yet, especially at $125/kwh, except there are plenty of competitors like CalBattery.
We used to talk about this genset style hybrid about twenty years ago. The key is constant speed duty cycle, which keeps the efficiency high. This is old technology and I'm surprised never to read that somebody has done it.
$150/kWh actual cost or covered by the cost of the car? Could you buy a battery pack from Tesla for that price, without buying the car too?
Actually, 1,600 cycles, at five cycles per week, would be 330 weeks, or 6.5 years. However, I believe I greatly underestimated the increase in lifetime. According to the graph on page 20-4 of this LFP battery study - http://upcommons.upc.edu/e-prints/bitstream/2117/15119/1/Lifetime.pdf, the lifecycle at 65% is 2,000. At 20% it is 20,000 cycles. So, what is the lifetime of the Envia battery at 20% DOD? If expansion of the silicon in the anode is what causes the degradation, maybe there would be a lot less expansion and much greater lifetime at smaller DOD.
In other words, if GM is testing the Envia battery in a volt, at 65% DOD and gets 400 cycles, this doesn't reflect the cycle lifetime if it were put into a BEV. If they put a large Envia battery, with a 200 mile range, in a BEV, they will get about 1,600 cycles. That would probably give more than 1000 weeks (20 years) of average driving.
@Arne - "cycles over only ~65% of capacity" But this is deep discharge. My point is that a large battery gives at the same time a long range and long lifetime by discharging only a little each day, with normal driving. The Li Iron Phosphate battery gets about four times the cycle lifetime at 20% DOD as it does with 65% DOD. Between 65% and 100% the curve is pretty flat, meaning 65% DOD lifetime is only 15% greater than 100% DOD. 80% DOD doesn't extend the lifetime more than 5%.
Actually a 100% DOD each week might give only a five year lifetime. But, keeping a 200 mile Envia battery at near full charge by plugging it in every night might allow a ten year lifetime. Why do 99% of battery articles only talk about deep discharge lifetimes and not small discharge lifetimes?
"400 cycles/72% remaining capacity" At $160 kwh, the Envia battery would a good choice for GM even at that cycle lifetime, but only for a BEV. Probably they only want to put it into a Volt, which relies on 100% DOD every day. Therefore, of course it's not good enough. But if it's put into a BEV, with 200 mile range, a 100% DOD would be once a week on average and it would last about ten years. But most likely the BEV's 200 mile battery would be kept between 70% and full charge by charging every night.
Power company reps have already said that they could build plenty of substations to power BEV charging stations. It will be less expensive than digging holes for storage tanks and pumps, and they won't "melt" the grid.
That deep-throated noise wakes me up at 6:00 AM every morning. Why would that be satisfying? HD owners are exist of corrupt politicians who allow HD to sell those because HD says they will go bankrupt if their customers can't harass the neighbors with loud noise. In the HarveyD spirit, I predict that in 2025, enough BEVs will be on the roads, that the only vehicles making noise will be HDs, and legislation will be passed to silence them with mufflers.
"Forget the 350-mile EV. At 70 MPH cruise" How many people drive 350 miles per day at constant 70 mph? Very few, so wasting the high output is a minor issue. Much more important is the high energy capacity and cycle lifetime. These Li-S batteries are likely to cost much less than Li-Ion and therefore, may result in a BEV vehicle that costs less than a half-ICE PHEV. With 350 mile range, cost is the bottom line, even if the lifetime is short.
It seems ridiculous when researchers publish results that measure the BEV targeted battery lifetimes in deep discharge cycles, when everybody know that nobody wants a car that only goes 50 miles. The 50 mile range would cover average mileage per day and assumes full discharge and charging each day. But if people won't buy less than 200 mile range, then the researchers should always report the battery lifetime in terms of partial discharge and recharge cycles.