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lebikerboy

For those of you interested in electric cars...

25 posts in this topic

The issue is not the electric car but the battery. More research time and money should be diverted to mass producing capacitors designed specifically for EV's. No rare earth materials will be needed, charging times become much quicker and capacitors will be much lighter than the batteries they will replace.

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Capacitors are not a feasible alternative, even the wonderful new ultracapacitors. Nowhere near the energy density needed. They may well have a role to play as their power density is phenomenal, so they can absorb or supply peak surge currents very well, but you need more storage than they are remotely capable of. Ultracapacitors for a limited amount of surge energy, backed up by battery storage energy is an excellent idea. Batteries can be much better storage devices if they don't have to handle sudden surges, especially charge surges (braking).Energy density = KW/H, Joules etc per unit of weight.Power density = maximum rate of charge/discharge per unit of weight.Both are important. Ultracapacitors excel at the later, suck at the former. Far more energy density than regular capacitors, still nowhere near what is needed.

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Experimental electric double-layer capacitors have demonstrated densities of 30 W·h/kg and have been shown to be scalable to at least 136 W·h/kg. For comparison, a conventional lead-acid battery stores typically 30 to 40 W·h/kg and modern lithium-ion batteries about 160 W·h/kg.

What energy density is needed to make super caps feasible?

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I'm no expert in the field. What I took from the bit of research I did was that real-world practical results were more in the range of 5-10 Wh/kg. Big difference between a single cell in a lab encased in a blast shell and a massive bank of them underneath your seat. With the extremely high potential discharge rate they make a pretty good bomb! I'm not really sure, like I say I'm no expert. Very interesting developments indeed, I'm watching it. Even at the current state they can certainly be of use for the sudden surges.

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With the extremely high potential discharge rate they make a pretty good bomb!

Fuses, breakers, IGBT's can easily and safely limit current.Gasoline can be very volatile as well. Edited by Huronlad

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Internal failure, not external is the "bomb" problem. Multiple cells in the same pack, if one fails, doesn't set off the rest, and doesn't stop the functionality of the pack no biggie, if there is a cascading failure look out!Again, very interesting developments, great potential, far from realization. Not ready for prime time.

Edited by Alex

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Only those in Vancouver or Montreal will get that, Francesco! :D

I think it's pretty commonly understood these days that LGBTs are everywhere!

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Internal failure, not external is the "bomb" problem.

The battery charging monitors on each cell can be used to ensure the batteries are discharging correctly as well. If the cells are not functioning correctly, either shut the whole system down and disconnect the battery out of the system or if the battery pack is broken up into sections, disconnect the affected section and limp the vehicle home.I suspect the manufacturers may go over board on safety and just have the car stop until the fault is fixed.

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Another reality check: The shocking truth about electric cars

As Dennis DesRosiers, a leading auto consultant, points out, consumers simply won’t pay a $20,000 premium for a vehicle that doesn’t go very far, isn’t very convenient, and runs out of juice as soon as you turn on the air conditioner.Of course, electric cars aren’t in mass production yet. And the technology is bound to get better and cheaper. Right? Not so fast...Electric cars...aren’t microchips, and Moore’s law doesn’t apply.Electric cars aren’t necessarily green at all. Electric vehicles require large amounts of electricity – so much that Toronto Hydro chief Anthony Haines says he doesn’t know how he’d get it. “If you connect about 10 per cent of the homes on any given street with an electric car, the electricity system fails,” he said recently. And if the extra electricity isn’t generated by renewable energy, then overall carbon dioxide emissions will go up, not down...

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It is going to be sometime before there are 550,000 EV in the GTA to worry about them causing brown-outs.

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A lot of FUD gets spread, most of the arguments laced with herrings of a certain colour. Ontario might have difficulty (doubtful claim), but BC and Quebec would not. The FUD-spreaders claiming pollution will go up fail to mention that the amount of energy it takes simply to refine crude oil into a gallon of gasoline -- before a car ever even gets to burn that gasoline -- is more than the amount of energy used by an EV to go a gallon-equivalent distance. In other words, according to the EPA the current fortwo ED has an 85 MPGe; the amount of energy the car uses to go 85 miles is less than the amount of energy it takes to produce one gallon of gasoline. That gallon ends up in some bubba's Silverado and gets burned off to go 13 miles.

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It is going to be sometime before there are 550,000 EV in the GTA to worry about them causing brown-outs.

And as we've said before, most EVs will (logically) be plugged into smart chargers and the Smart Grid. They will be charging overnight and off-peak, when much of Ontario's excess electricity generation isn't being banked (EVs will essentially constitute an energy storage bank), but rather is being burned off needlessly. You can't simply shut down a nuclear or thermal station at night, anymore than you can stop a river from flowing.

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You can't simply shut down a nuclear or thermal station at night, anymore than you can stop a river from flowing.

Both nuclear and thermal plants can be throttled down, thermal quickly, nuclear less so. Run-of-river plants can be slowed or stopped almost instantly but the potential energy is wasted as river flow. All conventional hydro plants with a dam and lake can be throttled down and the lake just rises a few inches overnight so no waste at all.

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Do they really throttle down nuclear and fossil fuel plants between 11 pm and 5 am? From all I've read it is even less efficient to do so.Either way, overnight is when most EVs will be charging. Unless Ontario is running at peak demand when everybody is asleep, I fail to see how "the electricity system fails."

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The part missing from that calculus is the energy signature of the raw materials that compose the electric car versus the ICE car.

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Do they really throttle down nuclear and fossil fuel plants between 11 pm and 5 am? From all I've read it is even less efficient to do so.

All generating units are engineered to be most efficient at 100 %Most can be readily throttled, but there is a very real co$t of inefficiency that gets added onto the overall cost of production.If a thermal generating station has, say 4 units, they will leave 3 at maximum and use one for throttling.It is also a very co$tly endeavour to bring a thermal generator up to operating temperature from a shutdown, or from a low-operating level, so there is no real possibility of doing that except for planned maintenance.'Green Generation' from Solar or Wind is so gonna really trouble systems, in that they can't allow more of it than they can have a back-up running in wait.Yup, I worked in Power Generation for over 10 years ... in a previous life ... in a previous millenium ...

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The part missing from that calculus is the energy signature of the raw materials that compose the electric car versus the ICE car.

Well, consider that there are less moving parts and simpler mechanicals. A 35 Kg motor versus a 70 Kg engine. No transmission versus a five-speed transmission. Truly, the big difference is the Lithium ion battery pack, and it the case of the ED, it's not even that large. The battery packs in EVs (for now) are very similar to those in laptops, cordless tools and mobile devices. End-of-life recyclability of the Li-ion packs is certainly better than much of an ICE engine and its peripheral systems.

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I've never seen that discussed other than normatively by gadabouts; someone qualified at an academic institution ought to do a environmental and energy footprint comparison report.

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I can see this type argument being made 120 years ago about the present gasoline and diesel powered automobile by the horse and buggy set. It makes sense to turn all forms of potential energy into electricity and then design all items needing energy to run on electricity. My 2 cents worthRoy

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Here is a report that makes sense to me. Or you can read the summary.

The article from Post #23 sounds like a rant, and I can't follow the calculations. It sounds like he expects that 13 million cars will need to be charged from completely flat in one hour on Sunday night.

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