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Charles Murray
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Re: Boeing back in the news
Charles Murray   1/22/2014 9:00:46 PM
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Well, yes, you would need a big flat-head to pry it out if it looked like this, Cabe. Fortunately, the automotive version won't be a gigantic coin cell.

Cabe Atwell
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Blogger
Re: Boeing back in the news
Cabe Atwell   1/20/2014 5:33:40 PM
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I'm guessing you need a really big flat-head screwdriver to pry it out of its housing when a replacement is needed.

Charles Murray
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Blogger
Boeing back in the news
Charles Murray   1/16/2014 8:30:10 PM
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It's interesting to see that Boeing's lithium-ion batteries are back in the news again after an incident in a Japan Airlines aircraft. We'll be reporting on it next week.

William K.
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Platinum
Re: But there is another concern
William K.   1/9/2014 7:45:23 PM
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As soon as I read that post I recalled that it had been quite interesting at the time, and it still is an interesting area of car technology. Probably an electric dragster could pull max acceleration for the entire quarter mile. Given some of those really sticky tires, that could be way faster than any normal engine driven racer. The limiutation will undoubtedly be the tires.

Charles Murray
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Blogger
Re: But there is another concern
Charles Murray   1/9/2014 7:13:04 PM
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You're right about wearing down the battery at the dragstrip, William K. A few years ago, when we did an article about EV drag racing, we interviewed a driver who used 848 lbs of batteries in his electric Pinto and consumed 1600 A at 360 V, which comes out to 0.576 MW of power. That runs the batteries down pretty quickly. Here's the link.

http://www.designnews.com/document.asp?doc_id=228440

 

William K.
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Platinum
Re: But there is another concern
William K.   1/7/2014 9:00:38 PM
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Charles, you are right about unpredictable types of battery abuse. My mention of vehicle AC is because we know about that one, not to imply tyhat there won't be others. Just imagine a vehicle with an alternative PROM installed, just like they do for the ECMs on some cars today. So we could see an EV dragster burning the tires for the whole quarter mile, and running the battery down to nothing in that same distance. Optimized consumption planning meets ultimate racing. It might be quite a show.

Charles Murray
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Blogger
Re: But there is another concern
Charles Murray   1/7/2014 6:52:43 PM
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Wlliam K, the AC issue you describe is one of many, I think, that will come up as EV batteries face the abuse of unpredictable consumers.

dimonic
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Iron
Re: But there is another concern
dimonic   12/18/2013 4:58:24 PM
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Indeed you could be right. Certainly conventional cars use a lot of watts on AC. I would have thought that systems for EVs would improve on this somewhat.

 

The tables here <http://www.nrel.gov/docs/fy00osti/28960.pdf> seem to indicate a lower range reduction than what you are suggesting.

William K.
User Rank
Platinum
Re: But there is another concern
William K.   12/18/2013 3:45:42 PM
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My assertion about AC reducing battery charge is based on the information that vehicle "road load" is less than ten horsepower. At least that was what they were setting for the dynomometer road load setting the last time I heard an emissions test being specified. And the automotive compressor requires three to four horsepower, and unlike driving the vehicle, the compressor runs 100% of the time. In addition there is that high powered blower, which would draw about 25 amps at 12 volts, which is a half horsepower or so. Both are a constant load, not one similar to the driving, coasting, and stopped mode of the city emissions test cycle. And city driving would probably consume less power because of slower speeds and being stopped more. 

Of course it is quite likely that the more streamlined cars currently on the market have an even lower road-load horsepower rating, which would leave the AC as an even larger portion of the battery load.

dimonic
User Rank
Iron
Re: But there is another concern
dimonic   12/18/2013 1:48:09 PM
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True enough re: battery cycles. However, unless people are expected to manage cycles carefully, doesn't a 1/4 discharge cycle charge have pretty much the same effect as a 3/4 discharge cycle? This would make the problem more one of a finite number of trips - with or without AC.

 

I am puzzled as to how AC will cut mileage down by more than 2/3. Are there actual measurements or statistics to back that claim?

 

That said, since I have a 60 km commute, with the improved range I could commute both directions on a single charge - which would certainly save me some cycles. However, here in Canada we either need AC or heat, with only about 3 months where one could driver with neither. Of course some of the heat could be "harvested innefficiency" (motor cooling) - so it probably does not take as much energy as AC. Either way, if I had a 300 km range, I could probably do my 2-way trip on one charge.

 

The 2013 Chevy Volt has a Toshiba battery that boasts 6000 cycles - so if I used two per day, the battery bank would last about 10 years. Of course I would need a 240v outlet at work, since the volt has a range of 60 km on battery.

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