Quote:
Originally Posted by dcb
batteries do not necessarily charge efficiently "The coulometric charging efficiency of nickel metal hydride batteries is typically 66%, " How to charge Nickel Metal Hydride Batteries.
and you have to charge the battery before you can discharge it.
Plus a few percents for converters/controllers/lights/heat/etc. |
That's only going to be true for DIY HEV conversions. Every mass produced EV/PHEV is going w/ Li batteries, and charging efficiency is much higher, around 90% or so.
Quote:
Originally Posted by dcb
So even suggesting that an EV is %90 efficient from the wall is coocoo.
I also don't think %15 is a fair number for ICE, it takes the driver and any recent advancements out of the equation. It is entirely possible to operate a car near it's peak efficiency, folks here do it all the time. Even if you look at a reasonably idiot proof efficiency car, the prius, it is rated at %37 (link also shows a well to pump of %79 and a well to wheels of %29) EFFICIENCY: "WELL-TO-WHEEL" ANALYSIS. -- Britannica Online Encyclopedia |
It's fair to say that most PHEVs/EVs aren't 90%. ~75% from the plug is closer to what most would see. Along the same lines a Prius isn't going to be at peak engine efficiency of 37% all the time, it'll be closer to high twenties in terms of average efficiency. The car has to warm up, light off the emissions system, and so on. Most new cars are probably around 20+% in terms of average efficiency and most hybrids are in the high twenties in terms of efficiency.
Quote:
Originally Posted by dcb
so, I'm still skeptical that electric is "all that" in the full life cycle efficiency department. I'm not convinced yet the BEV's dominate in efficiency full cycle. The land use is a good thing for electrics, but range and initial cost and availability make liquid fuels attractive for transportation.
Also, the rolling resistance/weight thing. The problem with extra weight is not just extra rolling resistance, but also you only get a small fraction of your acceleration energy back in electric regenerative braking.
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It depends on the specifics, but generally speaking an EV compact car will need ~1kWh/mile of electricity assuming we use something like subcritical coal, while a conventional gas version will need ~1.5kWh/mile of gasoline. A hybrid gas version would need about the same amount of energy per mile an electric would. As we move to generation methods like natural gas the EV drops to ~.75kWh/mile. Using renewables or fission can further reduce the amount of fossil fuel energy per mile needed.
Quote:
Originally Posted by JasonG
Well tell ya what,
when you build an EV that can pull a 16,000lb trailer at 55 MPH for 350 miles I'll conceed that electric is on equal terms.
Heck, if you can find one that can do either I might
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I don't think anyone is saying that either one is on equal terms. An engine can't beat a motor for reliability or efficiency and a motor can't beat an engine for refueling times or energy storage. Each one has it's advantages and disadvantages.