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  #41  
Old 12-14-2020, 04:48 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Lots of numbers thrown about.

Here a reliable source for electricity and the US grid. Generally, for the total grid, it is about 35% efficient in conversion from fuel to electricity and a 5-6% loss getting it to the home. It has not changed much in the last 15 yrs.

Much analysis was done for determining industry investment and benefit for emissions. A good hybrid light duty class vehicle yields overall about 80% (Prius) the reduction benefit of an all electric (Electric Vehicle Symposiums). People are not rushing to get hybrids for all of their purchases, and they don't have the cross country limitations.

Even hybrids are being watered down. My wifes new RAV4 Hybrid has half the battery capacity of the Prius and an inferior powertrain for hybrid electric (compared to Prius). It has better acceleration than the standard which she liked. I liked the better mileage. Calculated cost per mile was better.
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is of a meager and unsatisfactory kind.
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  #42  
Old 12-14-2020, 07:20 PM
Sam I Am Sam I Am is offline
 
Join Date: Jun 2018
Location: Amarillo, TX
Posts: 43
Default And the batteries deteriorate

I recently spoke to a Tesla owner in Denver who has a second home in Palm Springs. He mentioned that the battery capacity had deteriorated to the point that he cannot get more than 250 miles in a charge and does not drive it to Palm Springs. I don't know about you, but that is 550 miles too short for a days drive!
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  #43  
Old 12-14-2020, 07:46 PM
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bkervaski bkervaski is offline
 
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Location: Birmingham, Alabama
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Quote:
Originally Posted by Sam I Am View Post
I recently spoke to a Tesla owner in Denver who has a second home in Palm Springs. He mentioned that the battery capacity had deteriorated to the point that he cannot get more than 250 miles in a charge and does not drive it to Palm Springs. I don't know about you, but that is 550 miles too short for a days drive!
Some details missing here they don't deteriorate that much .. sounds like he has a problem .. but just curious why he doesn't just stop and top off the batteries? There are 5 superchargers between Denver and Palm Springs ...

That's 1000 miles .. I would top off maybe 3 times .. 15-30 minutes per charge .. these chargers are generally located in nice areas with restaurants .. works out nicely on a trip like that
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Last edited by bkervaski : 12-14-2020 at 08:00 PM.
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  #44  
Old 12-14-2020, 07:58 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 481
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Quote:
Originally Posted by Sam I Am View Post
I recently spoke to a Tesla owner in Denver who has a second home in Palm Springs. He mentioned that the battery capacity had deteriorated to the point that he cannot get more than 250 miles in a charge and does not drive it to Palm Springs. I don't know about you, but that is 550 miles too short for a days drive!
I drove double that one silly day. 1113 miles straight. Energy for the pickup truck came from gasoline that was easily refilled, and I was refilled by large coffees several times as well. I was driving to marry my wife, so significant motivation. I'd call it young and foolish, now almost 5 years later, it's a 2 day drive.

I have no doubt electric sport aircraft are coming, just not today. Well maybe technology demonstrator aircraft only. Certainty nothing practical or useful..yet. Look how far electric cars have come in the past 10 years, imagine what will happen in another 10 years.

Here's a great electric aircraft technology demonstrator: https://www.skiesmag.com/news/harbou...beaver-flight/. Although it wasn't a Tesla motor.

As for how environmentally friendly electric is, that depends on the local power generation technology. My area is predominately hydro-electric. Much of Ontario is nuclear and hydro-electric. Some wind and solar, but that's not a major contributor and mostly a "feel good" government project. All the coal plants are long decommissioned and being demolished, with the environmental disaster the toxic coal ash causes. One was turned into "bio-fuel" for a few years, ran on basically saw dust and scrap from the lumber industry. Nuclear is by far the best option for many areas. Yes nuclear has it's risks, but looking statically, a coal plant ash pile is significantly more damaging than the extremely rare nuclear accident or the nuclear waste storage/disposal. Hydro-electric is great too, but only works in areas with a steady and consistent water supply. Basically Great Lakes watershed.
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Last edited by David Z : 12-14-2020 at 08:06 PM. Reason: power grid source and environmental comments.
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  #45  
Old 12-14-2020, 08:01 PM
larosta larosta is offline
 
Join Date: Dec 2010
Location: Redlands, CA
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Default Thomas Edison on Battery Technology

"The storage battery is, in my opinion, a catch-penny, a sensation, a mechanism for swindling by stocking companies. The storage battery is one of those peculiar things which appeal to the imagination, and no more perfect thing could be desired by stock swindlers than that very self-same thing."


Feb 17, 1883 - Thomas Edison
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  #46  
Old 12-14-2020, 08:10 PM
echozulu echozulu is offline
 
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Location: Ocean City, MD
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Also a Tesla owner. For electric vehicles at least, the question isn't "how much range can I get off of one charge" but "can I make the next charger". Since the number and locations of superchargers are limited, a 300 mile range and a 200 mile range in practice may have to stop at roughly the same superchargers anyways. As an owner of an M3 SR+, I get about 200~220 miles off one charge in practice, when charging to 100 percent for a road trip. I've made it cross country twice. The only time I hesitate is when doing road trips to national parks or other types of outdoor activity. When you're heading city to city like Denver to Palm Springs, the density of superchargers means a 250 mile range is more than enough to allow you to pick and choose which superchargers to stop at depending on food and entertainment options. And the network is only expanding from here.

Coming back to the airplane topic, if we use current tech, it's going to be all about charger density. EVs excel at around town travel, when you can return to your home/hangar at the night and charge up. Going cross country, there will be some owners who will gladly trade the extra time and stops for better performance and presumably, safer engines. Chicken and egg issue though. Without the powertrain, no one wants to build charging infrastructure at airports. Without the charging infrastructure, no one wants to buy electric planes.

Also, may not be cheap to build either. Tesla treats their network as marketing and doesn't expect it to turn a profit. EVgo and Electrify America prices are atrocious, something around 50 cents per KWH. This may indicate that charging infrastructure is much harder to make a profit off of than we thought, and that's with a much larger user base than general aviation.
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  #47  
Old 12-14-2020, 08:46 PM
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bkervaski bkervaski is offline
 
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Quote:
Originally Posted by echozulu View Post
Also a Tesla owner. For electric vehicles at least, the question isn't "how much range can I get off of one charge" but "can I make the next charger". Since the number and locations of superchargers are limited, a 300 mile range and a 200 mile range in practice may have to stop at roughly the same superchargers anyways. As an owner of an M3 SR+, I get about 200~220 miles off one charge in practice, when charging to 100 percent for a road trip. I've made it cross country twice. The only time I hesitate is when doing road trips to national parks or other types of outdoor activity. When you're heading city to city like Denver to Palm Springs, the density of superchargers means a 250 mile range is more than enough to allow you to pick and choose which superchargers to stop at depending on food and entertainment options. And the network is only expanding from here.

Coming back to the airplane topic, if we use current tech, it's going to be all about charger density. EVs excel at around town travel, when you can return to your home/hangar at the night and charge up. Going cross country, there will be some owners who will gladly trade the extra time and stops for better performance and presumably, safer engines. Chicken and egg issue though. Without the powertrain, no one wants to build charging infrastructure at airports. Without the charging infrastructure, no one wants to buy electric planes.

Also, may not be cheap to build either. Tesla treats their network as marketing and doesn't expect it to turn a profit. EVgo and Electrify America prices are atrocious, something around 50 cents per KWH. This may indicate that charging infrastructure is much harder to make a profit off of than we thought, and that's with a much larger user base than general aviation.
For the uninitiated ... SR+ means "Standard Range Plus" there are Long Range and Performance options as well ... as a comparison, my Performance S gets 350 miles if I go easy on it, 315'ish miles if I drive .. ahem .. cough cough .. "normal"
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Last edited by bkervaski : 12-14-2020 at 09:09 PM.
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  #48  
Old 12-14-2020, 10:31 PM
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newt newt is offline
 
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We already know enough about aerodynamics to make very low-drag airplanes (the Eta sailplane exceeds 70:1), but the "normal" planform for a 2-seat sport aircraft or a 4-seat utility aircraft places a practical limit on what's achievable there. It's unlikely that technological advances will make airframes much better than they are now, they're probably pretty close to as good as they'll ever get.

We also already know enough about electric motors to get very high efficiency power transfer: Electric motors that are better than 95% efficient are readily available. No matter how much additional technology you develop, you're only going to close-out the residual 5%, and not move the needle very far; In efficiency terms, electric motors are probably near as good as they'll ever get.

So then we can look at the battery system. Plenty of people who know more about it than me have already weighed in on this thread. Current batteries are 0.2 - 0.3 wH/kg, which is a factor of 20-30 less than liquid petroleum fuel, so if you keep everything else constant, including the weight, converting an airplane from IC to electric will substantially reduce its endurance.

... which is consistent with what we see from, e.g., Pipistrel, where the Virus yields nearly 6 hours endurance as a gasoline aircraft, but is a 30 minute circuit trainer when it's battery-powered and sold as an Pipistrel Alpha Electro.

So to get an aircraft that's at least as capable as a current generation gasoline airplane, we'd need battery energy density (W/kg) to increase by something in the realm of 10x-15x. Maybe more, to trade off battery charge time vs fuel tank refill time on multi-leg trips, and to account for the extra weight of the cooling systems higher energy density will want.

I don't think we see that coming down the pike.

There are research batteries in labs, yet to be commercialized, that are maybe 2x as dense. Maybe we can theorize about another doubling on top of that, and suggest that it's feasible to expect 4x in the medium-long term future.

But is anyone seriously expecting 10x-15x improvement? We've been making batteries for 200 years, they've been through efficiency spurts already; Do we think there's much more to come?

I'm skeptical. I'd love to be wrong, but I don't realistically expect that I'll see practical general-purpose electric aircraft in my lifetime.

Niche purposes, like aerobatics, air racing, motorgliders, etc -- Sure. Even right now. I know a guy with an electric motorglider, and the instructor who sent me solo has an Alpha Electro, so it's definitely happening.

But general purpose? "Load the family on board and fly to a vacation" that we can do with our airplanes now? I just don't see it happening any time soon. The only gains left to be had are in relation to batteries, and the pace of advancement just isn't there.

- mark
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  #49  
Old 12-14-2020, 10:56 PM
terrye terrye is offline
 
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Location: Vancouver, BC, Canada
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Default Tesla Electric powered RV

Quote:
Originally Posted by David Z View Post

Here's a great electric aircraft technology demonstrator: https://www.skiesmag.com/news/harbou...beaver-flight/. Although it wasn't a Tesla motor.
First flight of the electric Beaver was now over a year ago, practically in my back yard. A big splash of publicity in magazines and local TV news and then...nothing. I haven't heard of it being flown since. This was a megabuck effort with lots of really smart people. The motor and motor controls were excellent. I wasn't there, but I heard a rumor that the payload of eBeaver was 190 lbs, ie. the pilot (normal empty weight 3000 lb, normal gross weight 5100 lb). In other words, all the payload was taken up by the batteries.

I think we'll be waiting a long time before the power density of batteries allows a commercial payload to be carried.
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  #50  
Old 12-15-2020, 07:01 AM
Mike Houston Mike Houston is offline
 
Join Date: Dec 2020
Location: Bushmills
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what you need is the best of both worlds. For example current technology allows about 300watts/kg in a battery. So if you install a 20kwhr battery weighing about 70kgs in a plane and a small electric motor to drive your prop you probably have enough stored power to get any RV home/safe landing under electric power alone.

Alongside this you install a 230kw AUDI diesel engine as used in A6. This weighs about the same as a lycoming 0 -360 or 390 and produces as much power as a IO 540 or more. This engine only job is to keep the battery charged full so it needs no special design features as an aircraft engine. It will also run on Jet A.

You are safe because if the engine stops working you have a full electric battery to get you to safe landing spot and electric motors have almost no moving parts so very unlikely to break down. The AUDI engine will be about $10-$15k the battery price is about $120 a kw at present so $2400 in this scenario and you will need an electric motor and some electronics to manage the whole shabang...another $2k.

So for less than $20k you have a jet A fueled battery electric aircraft powerplant with the safety of battery power to get you home if the diesel engine gives up.....all the stupid engine rebuilds and maintenance issues almost disappear overnight
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