Electric Airplanes?

[jsstevens]

yes it did. Fortunately no major injuries.
But this also brought up for me a question about electric motors, in cars, planes, whatever.
I notice that sometimes in phones for example that the loss of battery power is not linear.
A fully charged whatever, may take a good while to start dropping in capacity...then even out for a while from 80% down to some number, say 30%. But not always, sometimes from 30% or so, it seems to start going down a good deal more rapidly.

I asked a coworker that has a small electric car, and he confirmed that he experiences that with his car as well.

and they don’t seem to be able to adjust the readout for batteries, such that they could factor in the different rates of consumption, or don’t care to. He says on his car the calculated range changes for the worse as he gets lower. So at one point calculated he has 20 km range, but he can drive 5 km, and then see he now doesn’t have a range of 15, but instead now it is 8, etc.

Given that we are used to fuel burn rates that for a given setting will be predictable, so we can plan for required reserve fuel at destinations, time wise...

I am not sure, and maybe this will be rectified, but it seems that currently it is comforting that a pilot can with confidence in the numbers calculate remaining flight time, fuel consumption. But how much variance is there with purely electrical and batteries?

I'm not sure how it works with electric motors (I would not contradict someone with personal experience!) but with many modern electronic devices, they use so little power that they are far down the charge curve before you can tell any degradation. Case in point: wireless microphones. Two decades ago, a 9V powered wireless microphone would last 6ish hours, but you could hear the difference (subtly, but I was running sound and listening on headphones) with easily an hour before it quit. Now they will run 20+ hours on a AA 1.5V battery, but if you hear a difference, you might have 10 minutes, sometimes less.

 

[AKBill]

Sure eclectic motors are clean to the environment. My question is what produces more harmful byproducts to the environment, producing electricity to charge batteries to run the electric motor or running an internal combustion engine?

 

[jsstevens]

Sure eclectic motors are clean to the environment. My question is what produces more harmful byproducts to the environment, producing electricity to charge batteries to run the electric motor or running an internal combustion engine?

It is easier (from an engineering and logistics perspective) to clean the output of a central, large, plant that produces electricity than to clean all the ICE running around. That does not mean that they are all properly cleaned, nor that we're not cleaning the output of ICE, just from an engineering and logistical perspective, it's more efficient.

 

[flyingcheesehead]

But this also brought up for me a question about electric motors, in cars, planes, whatever.
I notice that sometimes in phones for example that the loss of battery power is not linear.
A fully charged whatever, may take a good while to start dropping in capacity...then even out for a while from 80% down to some number, say 30%. But not always, sometimes from 30% or so, it seems to start going down a good deal more rapidly.

I asked a coworker that has a small electric car, and he confirmed that he experiences that with his car as well.

and they don’t seem to be able to adjust the readout for batteries, such that they could factor in the different rates of consumption, or don’t care to.

It's the last one. "Don't care to."

Battery voltage vs capacity is non-linear, even with a constant current draw from the battery. And if you increase the current draw, the voltage will go down instantly. For example, when starting the TBM, we generally have a battery voltage a bit over 25 just prior to start, but when you flip the starter on (which can draw 400 amps), the voltage will quickly drop to about 14. As the engine spins up, the current draw goes down, and the voltage comes back up.

A device that shows percentage capacity and has an apparent non-linear discharge rate is probably just trying to map voltage to percentage without accounting for any other variables. And in an electric car, there are a lot of variables: Battery temperature, OAT, elevation change, cabin HVAC requirements, tire pressure, and driving style. Most manufacturers don't bother trying to account for all of those, so EV drivers have come up with a name for the remaining battery readout: The GOM.

Guess-O-Meter.

Now, those manufacturers who only produce EVs - IE, Tesla - Have put a bit more work into theirs. Still not an exact science, but a big improvement over most others. The three EVs I've owned have each clearly ignored major variables. The Volt doesn't seem to pay any attention to driving style, for example. If you're a leadfoot, you'll never get the range shown, whereas if you're a hypermiler you'll do way better than it says. The Fusion Energi did pay attention to that, but maybe too much so. The i3 wasn't very good at adjusting for OAT.

Given that we are used to fuel burn rates that for a given setting will be predictable, so we can plan for required reserve fuel at destinations, time wise...

The good thing with airplanes is that they take most of the variables away. You'll be running at full power for climb and then some percentage of full power for cruise, and then reducing for descent and landing. On a longer leg or with a lower fuel load, my fuel flow will be flashing at me and sometimes indicating even a negative fuel over destination number during the climb, and when I get leaned out in cruise it gets happier. It'd be relatively easy to meet that standard for a battery remaining readout, and if it's integrated with a glass panel could potentially even use the altitude bug, flight plan, and previous behavior to do even better.

Using "fuel" (current) flow and groundspeed like today's totalizers do, and potentially OAT and battery temp, would make it relatively easy to have an accurate time remaining number. Also, it's not like you just instantly lose all power when the battery runs down. Li-Ion batteries do need a battery management system (BMS) that will keep the batteries from actually running all the way down because they are physically damaged by being emptied.

However, that BMS could also give you an hour warning, and at 1/2 hour reduce you to 50% power or something and tell you to land immediately. Finally, there could probably be a guarded emergency button/switch that would disable the BMS and dip below the minimum reserve in the event you had to use more power to go around when making your reduced-power landing.

The other thing with batteries is that you don't have to worry about fuel unporting, managing which fuel is in which tanks, etc. You'll just have an on/off switch and that's it.

 

[flyingcheesehead]

Sure eclectic motors are clean to the environment. My question is what produces more harmful byproducts to the environment, producing electricity to charge batteries to run the electric motor or running an internal combustion engine?

The internal combustion engine is worse for the environment.

The generally accepted figure is that it takes 8 kWh to refine a gallon of gasoline. That 8kWh will make a car go 32 miles or so. That means that even if the car's engine were zero emission, you'd have to get 32mpg to equal the environmental impact of an electric motor. And, of course, the car's engine is not zero emission.

If you're interested in what the break-even MPG figure is based on your local utility's mix of power generation, here's the latest map (from early 2018):

 

[Velocity173]

The internal combustion engine is worse for the environment.

The generally accepted figure is that it takes 8 kWh to refine a gallon of gasoline. That 8kWh will make a car go 32 miles or so. That means that even if the car's engine were zero emission, you'd have to get 32mpg to equal the environmental impact of an electric motor. And, of course, the car's engine is not zero emission.

If you're interested in what the break-even MPG figure is based on your local utility's mix of power generation, here's the latest map (from early 2018):

Yeah but electric isn’t the silver bullet solution to our environmental issues either. They have their drawbacks.

http://energyskeptic.com/2018/not-enough-lithium-for-electric-car-batteries/

https://www.inverse.com/article/60739-electric-cars-could-pose-a-major-environmental-challenge

https://www.bloomberg.com/graphics/2017-lithium-battery-future/

 

[flyingcheesehead]

Yeah but electric isn’t the silver bullet solution to our environmental issues either. They have their drawbacks.

http://energyskeptic.com/2018/not-enough-lithium-for-electric-car-batteries/

https://www.inverse.com/article/60739-electric-cars-could-pose-a-major-environmental-challenge

https://www.bloomberg.com/graphics/2017-lithium-battery-future/

That's an interesting choice of links.

The first article says there isn't enough lithium.

The second says there's going to be too many batteries in old cars. (Hello, recycle them and get the lithium and other materials back... Duh.)

The third, despite its headline, says that there's actually plenty of lithium and that extraction costs are the problem, but that even if lithium prices rise by 300% it only changes the price of a battery pack by 2% because there isn't much lithium in them (just 11% of the cathode).

 

[Velocity173]

That's an interesting choice of links.

The first article says there isn't enough lithium.

The second says there's going to be too many batteries in old cars. (Hello, recycle them and get the lithium and other materials back... Duh.)

The third, despite its headline, says that there's actually plenty of lithium and that extraction costs are the problem, but that even if lithium prices rise by 300% it only changes the price of a battery pack by 2% because there isn't much lithium in them (just 11% of the cathode).

Lol! Yeah I noticed that also. But it brings up some important questions as we go down the EV road. Do we fully understand the implications of going full electric and it’s impact on the environment? Do we have the capacity to recycle at this point? How much lithium and cobalt is there?

Our electric grid, in its current form, is estimated to only be able to handle a 25 % electric fleet. Mining will continue to go into areas that are “protected” and there will be consequences for the environment. EV isn’t a panacea and I believe we need a mix of ICE and EV to have any sort of sustainable future.

 

[flyingcheesehead]

Lol! Yeah I noticed that also. But it brings up some important questions as we go down the EV road. Do we fully understand the implications of going full electric and it’s impact on the environment? Do we have the capacity to recycle at this point? How much lithium and cobalt is there?

I think we have a much better idea of the solutions to these issues today than we did for the issues with ICEVs around the time the Model T came out.

I'm sure we don't fully understand the implications. There will be some things that surprise us no matter how well we plan, and we'll come up with solutions to those issues as we encounter them.

We do have the capability to recycle batteries. Capacity is lagging, but that's OK - EV batteries shouldn't be coming off of vehicles in large numbers until those vehicles are being retired in large numbers, so recycling capacity can lag manufacturing capacity by a decade or more without any ill effect. Right now, the batteries that come off of crashed EVs are getting snapped up and repurposed by enthusiasts - I know people who are using modules from those packs to build electric motorcycles, lawn mowers, solar storage arrays, and other stuff. By the time the supply of used EV batteries grows beyond the demand that exists today, we should have plenty of capacity to recycle them because at that point the demand is going to come from new EV batteries.

Our electric grid, in its current form, is estimated to only be able to handle a 25 % electric fleet. Mining will continue to go into areas that are “protected” and there will be consequences for the environment. EV isn’t a panacea and I believe we need a mix of ICE and EV to have any sort of sustainable future.

Probably not forever, though. Certainly at this stage we need a mix because there's a lot of fossil fuel powered things that just aren't practical to replace with electric yet. Cars (at least Teslas, with their charging network) are practical to be replaced now. Delivery vans and such are right around the corner, and Tesla and others will have semi tractors out in the next couple of years. More specialized vehicles will likely take longer.

I also expect that we'll see some major changes in other areas. I don't think the airline industry is going to look anything like it does today 50 years from now. I'm imagining that there will be autonomous air vehicles of some sort that will hold between 8-20 passengers at most, and that the hub-and-spoke system will be a thing of the past. Customers would surely much rather hop onto something that will take them directly to their destination instead of visiting Atlanta yet again... And since it's difficult to hijack an autonomous aircraft and there isn't enough attention to be gained by doing so, we can likely dispense with the whole TSA nonsense too. It'd make air travel far more convenient, and without the huge size of today's airliners there are many more possibilities for propulsion as well.

 

[Velocity173]

I think we have a much better idea of the solutions to these issues today than we did for the issues with ICEVs around the time the Model T came out.

I'm sure we don't fully understand the implications. There will be some things that surprise us no matter how well we plan, and we'll come up with solutions to those issues as we encounter them.

We do have the capability to recycle batteries. Capacity is lagging, but that's OK - EV batteries shouldn't be coming off of vehicles in large numbers until those vehicles are being retired in large numbers, so recycling capacity can lag manufacturing capacity by a decade or more without any ill effect. Right now, the batteries that come off of crashed EVs are getting snapped up and repurposed by enthusiasts - I know people who are using modules from those packs to build electric motorcycles, lawn mowers, solar storage arrays, and other stuff. By the time the supply of used EV batteries grows beyond the demand that exists today, we should have plenty of capacity to recycle them because at that point the demand is going to come from new EV batteries.



Probably not forever, though. Certainly at this stage we need a mix because there's a lot of fossil fuel powered things that just aren't practical to replace with electric yet. Cars (at least Teslas, with their charging network) are practical to be replaced now. Delivery vans and such are right around the corner, and Tesla and others will have semi tractors out in the next couple of years. More specialized vehicles will likely take longer.

I also expect that we'll see some major changes in other areas. I don't think the airline industry is going to look anything like it does today 50 years from now. I'm imagining that there will be autonomous air vehicles of some sort that will hold between 8-20 passengers at most, and that the hub-and-spoke system will be a thing of the past. Customers would surely much rather hop onto something that will take them directly to their destination instead of visiting Atlanta yet again... And since it's difficult to hijack an autonomous aircraft and there isn't enough attention to be gained by doing so, we can likely dispense with the whole TSA nonsense too. It'd make air travel far more convenient, and without the huge size of today's airliners there are many more possibilities for propulsion as well.

Off topic but did you do the software recall on your Volt?

 

[Palmpilot]

Another issue to plan for regarding fully-electric vehicles is how to deal with "public safety power shutdowns" in high-fire-danger conditions like we've started to have in California.

 

[RyanShort1]

And since it's difficult to hijack an autonomous aircraft and there isn't enough attention to be gained by doing so, we can likely dispense with the whole TSA nonsense too.

Of that I am skeptical, though I would like to,do away with TSA, for sure.

 

[LongRoadBob]

It's the last one. "Don't care to."

Battery voltage vs capacity is non-linear, even with a constant current draw from the battery. And if you increase the current draw, the voltage will go down instantly. For example, when starting the TBM, we generally have a battery voltage a bit over 25 just prior to start, but when you flip the starter on (which can draw 400 amps), the voltage will quickly drop to about 14. As the engine spins up, the current draw goes down, and the voltage comes back up.

A device that shows percentage capacity and has an apparent non-linear discharge rate is probably just trying to map voltage to percentage without accounting for any other variables. And in an electric car, there are a lot of variables: Battery temperature, OAT, elevation change, cabin HVAC requirements, tire pressure, and driving style. Most manufacturers don't bother trying to account for all of those, so EV drivers have come up with a name for the remaining battery readout: The GOM.

Guess-O-Meter.

Now, those manufacturers who only produce EVs - IE, Tesla - Have put a bit more work into theirs. Still not an exact science, but a big improvement over most others. The three EVs I've owned have each clearly ignored major variables. The Volt doesn't seem to pay any attention to driving style, for example. If you're a leadfoot, you'll never get the range shown, whereas if you're a hypermiler you'll do way better than it says. The Fusion Energi did pay attention to that, but maybe too much so. The i3 wasn't very good at adjusting for OAT.



The good thing with airplanes is that they take most of the variables away. You'll be running at full power for climb and then some percentage of full power for cruise, and then reducing for descent and landing. On a longer leg or with a lower fuel load, my fuel flow will be flashing at me and sometimes indicating even a negative fuel over destination number during the climb, and when I get leaned out in cruise it gets happier. It'd be relatively easy to meet that standard for a battery remaining readout, and if it's integrated with a glass panel could potentially even use the altitude bug, flight plan, and previous behavior to do even better.

Using "fuel" (current) flow and groundspeed like today's totalizers do, and potentially OAT and battery temp, would make it relatively easy to have an accurate time remaining number. Also, it's not like you just instantly lose all power when the battery runs down. Li-Ion batteries do need a battery management system (BMS) that will keep the batteries from actually running all the way down because they are physically damaged by being emptied.

However, that BMS could also give you an hour warning, and at 1/2 hour reduce you to 50% power or something and tell you to land immediately. Finally, there could probably be a guarded emergency button/switch that would disable the BMS and dip below the minimum reserve in the event you had to use more power to go around when making your reduced-power landing.

The other thing with batteries is that you don't have to worry about fuel unporting, managing which fuel is in which tanks, etc. You'll just have an on/off switch and that's it.

Great response and write up. And yup...as current goes up voltage drops (ohms was able to pass a law on that, I think even Watt voted for it!)
Good explanation about the various factors too, and ideas for improvement.

Here in Norway we have a LOT of electric cars now. I haven’t gone ove to it, but there are problems in the tough winters here with enough charging points, ettiquete aroundthem (some fights broke out, Someone hogs the charge point with long queue when he’s up to 80, but it takes as long from 80 to 100 as from low to 80) plusnot enough, etc. We have had instances of electric cars on fire (the non arson ones) but now that winter is here again, there have been a few fires from people trying to charge us their cars at home, on the cheap. Instead of running a circuit with hefty enough wiring and not least the receptacle, they are just plugging into a regular outlet. Normal (220 vac) outlets here aren’t built to support the weight of the plug, and not dimensioned for the heavy duty charging over time and so...more garage fires.

Of course, pilots wouldn’t do that!

I guess there it’s hard to judge the relative danger of fire, between fuel and lithium battery driven, say after a bad forced landing. Petroleum is sure bad enough but honestly the intensity of lithium fires scares me a bit. It seems more intense and to get there very quickly. Of course, Avgas isn’t safe either.
But it’s more familiar.

 

[Dan Thomas]

The second says there's going to be too many batteries in old cars. (Hello, recycle them and get the lithium and other materials back... Duh.)

I'd want to know the details of recycling. The lithium would have to be separated from whatever is has become chemically bound with, and that might need enormous amounts of energy. For example, aluminum didn't come into wide use until the electrical smelting process was developed, and it takes the equivalent of one household's worth of electricity for one year to extract one pound of aluminum.

 

[flyingcheesehead]

Off topic but did you do the software recall on your Volt?

If you mean the one where they flash the battery, yes, a bit over a year ago. If there's a new one since then, I'm unaware of it.

Another issue to plan for regarding fully-electric vehicles is how to deal with "public safety power shutdowns" in high-fire-danger conditions like we've started to have in California.

Certainly an interesting topic. Oddly enough, electric vehicles could actually help the situation, if the grid is sophisticated enough to do something like isolate a neighborhood or individual houses (which many folks build in when they add solar) because vehicle-to-grid technology could allow for major transmission lines to be shut down in some areas without causing a complete blackout. But, I bet the PG&E situation gets worse before it gets better.

now that winter is here again, there have been a few fires from people trying to charge us their cars at home, on the cheap. Instead of running a circuit with hefty enough wiring and not least the receptacle, they are just plugging into a regular outlet. Normal (220 vac) outlets here aren’t built to support the weight of the plug, and not dimensioned for the heavy duty charging over time and so...more garage fires.

Interesting. I did char one of my outlets in my garage before I knew better. Old, tired outlets that were installed when a house was new aren't likely to be the best thing to plug into. Even if you use a standard outlet, it's best to get a new, contractor-grade one and side-wire it. It's also best not to use the portable EVSE that comes with the car if you're actually taking it with you, since the frequent unplugging and replugging will loosen up the outlet over time.

I expect there will be some bumps in the road with both electric cars and electric airplanes. After all, if you think about it, we're pretty much where we were in the 1930s or so with gasoline. I bet the pumps back then didn't have the "turn off your engine", "no smoking", etc signs, vapor recovery systems, and all of the other things that make filling your car with a highly volatile flammable substance relatively safe these days.

I guess there it’s hard to judge the relative danger of fire, between fuel and lithium battery driven, say after a bad forced landing. Petroleum is sure bad enough but honestly the intensity of lithium fires scares me a bit. It seems more intense and to get there very quickly. Of course, Avgas isn’t safe either.
But it’s more familiar.

For a few reasons, I think I'd rather have a battery fire than a 100LL fire. 100LL also burns very intensely from what I've heard (I know some people who have gone through airport FD training where they used an actual 100LL fire) but after a crash, the (liquid/vapor) fuel can spill and spread to a large area pretty quickly, whereas the solid lithium will stay where it is. I've seen a video of a Cirrus crash where the fire went from zero to fully engulfing the airplane in a single video frame (1/30th of a second) because the wing tanks ruptured - The previous frame shows a cloud of fuel going everywhere, basically a big "splash" that found an ignition source (likely the hot engine exhaust) and that's all she wrote.

That's another thing - A battery fire will be caused by something shorting, heating up, and then starting on fire. That's at least going to take several seconds, and be very localized, so you should have both time and space to get away.

 

[Velocity173]

If you mean the one where they flash the battery, yes, a bit over a year ago. If there's a new one since then, I'm unaware of it.

HPCM2. I got it in the mail a few days ago. A cell balancing upgrade but I’m hearing from it’s taken a toll on range for most people. Not sure I’m going to get it done.

 

[Shuswap BC]

https://www.timescolonist.com/busin...version-to-electric-powered-flight-1.23847737

 

[Dan Thomas]

That's another thing - A battery fire will be caused by something shorting, heating up, and then starting on fire. That's at least going to take several seconds, and be very localized, so you should have both time and space to get away.

Not in an airplane, you won't. And lithium has its idiosycrasies when it comes to charging, which is why we don't yet see Gill lithium aircraft batteries. Concorde is bringing them out, but check out their caveats: http://concordebattery.com/lion.php

 

[Brad Smith]

Airplane demands are quite different than cars and other ground transportation. Imagine making full power on takeoff and climb and cruising at 75% compared to an automobile loafing along requiring about 20hp most of the time. Putting the demands of an aircraft on batteries increases the heat buildup and the possibility of fire. I have experienced lithium battery fires and they burn with a very intense heat. Not good for something that cruises at 8,000 above the ground.
I believe we have a long way to go before a truly useful electric airplane makes it to market. While the development taking place is good, I wouldn't be surprising if they “hit a wall” and discover that they will never match the capability of a ICE powered airplane.

 

[flyingcheesehead]

Not in an airplane, you won't.

Why not?

 

[flyingbrit]

it takes the equivalent of one household's worth of electricity for one year to extract one pound of aluminum.

This does not pass the sniff test. A household uses a few hundred dollars of electricity per year. But one pound of aluminum obviously does not cost a few hundred dollars. According to this source, 2 lbs of aluminum needs 15kW-H for smelting:

http://www.madehow.com/Volume-5/Aluminum.html

 

[MIFlyer]

We're on our second electric car (a BMW i3), and our usage patterns are pretty non-intensive (nee "ideal" for an EV). Neither of us commute, so it's our "grocery getter". We only charge it with a 120V charger, which adds 4 miles per hour of charge. I think it has a max draw of 12 Amps. It has a 120 mile range when full, so it needs 30 hours to go from 0 to hero. Very, very rarely, will we use the onboard generator ("Range Extender"). If this was not enough, I could install a 240V/40A charger in my home.

Mapping this to the plane: I've flown the plane 9 hours this month. That means it has sat idle for about 710 hours.

Let's even go all out and do math on the 600hp. (Play along, I may make an error here )

At 750W per hp, this month I used 9 hours x 600hp x 750W = 4 Million WHr or 4,000 kWh

At 120V/12A, or 1.4kW, I'd need 2,857 hours. Oops.

At 240V/40A ,or 9.6kWh, I'd need 416 hours of charge.

So Barons need "Level 2" Charging.

...

Weight-of-batteries problem aside, if I have a hangar lease, and I have a 120V outlet in my hangar that my landlord pays the electricity for, well, it looks like I could charge about 1,000 kWh of airplane on his dime each month. With a 150hp motor, that's ~8 hours per month of free flying.

That's 100 hours per year of a C172/PA28-class plane.

I think that's typical usage of most plane owners, no?

But even if you paid for electricity you’d only be out about $400 for 4,000 kWh of energy. Vs the 225 gallons of a gas you burned at $5 = $1,125

So you’d have saved $700 in fuel this month


Sent from my iPad using Tapatalk

 

[jonvcaples]

Interesting discussion so far. A local company is developing a 2 seat electric trainer that looks vert promising and, according to their spokesman at Red Bird Migration is starting development of a 4 seat airframe. They have great ideas and hopefully will succeed.

The tall pole in the tent is battery technology. Until the current limitations of charging, weight, and power density can be overcome progress will be slow. Today charging is the biggest hurdle. Consider:

1-Already discussed limitations of current charging schemes (large amount of power required, limited availability, etc.).

2-The faster you charge a battery the more heat you produce. This must be dissipated to avoid damage to the battery itself and the structure around the battery. One way to resolve this problem is to develop easily changeable battery packs. Spare battery packs could be stockpiled at FBOs and charged overnight when current electrical grid usage is normally at its lowest. Another possibility might be developing a way to cool the batteries while charging.

3-Current battery technology is extremely finicky. Physical mishandling or electrical mistakes (short circuit or overcharging) can cause fire, explosion, or other catastrophic events. We had a laptop computer battery fail resulting in a fire that burned several square feet of carpet. Fortunately we were in the room as this happened and were able to limit the damage. The fire department (thank you guys and gals!) told us that we were lucky on several accounts. First, we were there and awake when it happened. Second, if we had been asleep the fumes from the battery and carpet could have disabled us. Third, the fire could have spread to other rooms and potentially consumed the whole house.

Watching the future unfold will be interesting!

 

[Dan Thomas]

This does not pass the sniff test. A household uses a few hundred dollars of electricity per year. But one pound of aluminum obviously does not cost a few hundred dollars. According to this source, 2 lbs of aluminum needs 15kW-H for smelting:

http://www.madehow.com/Volume-5/Aluminum.html

From http://shrinkthatfootprint.com/average-household-electricity-consumption
...we read: In the US typical household power consumption is about 11,700 kWh each year...

So yes, I'm off by a factor of 1560 or so. I read that original figure somewhere a long time ago. Still, I came across articles that say a lot of smelters are losing money due to the cost. In BC, where I grew up, Alcan had their own hydroelectric dam to generate the vast power required for the smelter. Smelters typically need their power to cost around $.03/kwH.

 

[Dan Thomas]

Why not?

I was referring to lithium batteries and their habit of lighting up at most inconvenient times if they're charged too fast or something. You won't be jumping out of the airplane to get away from some threat. Not in flight anyway.

Lithium also hates water.

 

[Kenny Phillips]

Of that I am skeptical, though I would like to,do away with TSA, for sure.

But one can attempt to damage or destroy that aircraft, so the TSA will live on regardless.

 

[GeorgeC]

https://spectrum.ieee.org/energywis...ims-to-double-the-range-of-electric-airplanes

 

[Salty]

https://spectrum.ieee.org/energywis...ims-to-double-the-range-of-electric-airplanes

With two more years of development they expect to get 500 cycles out of the batteries. So, if an operator is charging once a day (not sure how they can make a business on one charge a day, but that’s another story) you’ll have to buy a new, very expensive cutting edge battery pack every 17 months. IF they achieve their promised goal two years from now.

 

[Velocity173]

With two more years of development they expect to get 500 cycles out of the batteries. So, if an operator is charging once a day (not sure how they can make a business on one charge a day, but that’s another story) you’ll have to buy a new, very expensive cutting edge battery pack every 17 months. IF they achieve their promised goal two years from now.

And 500 cycles isn’t “par for the course” for lithium ion batteries. They get far more cycles out of them than that. Just my Volt battery alone was designed to go 5,000 cycles and only lose 10 % capacity.

 

[Salty]

And 500 cycles isn’t “par for the course” for lithium ion batteries. They get far more cycles out of them than that. Just my Volt battery alone was designed to go 5,000 cycles and only lose 10 % capacity.

Maybe it was a typo

 

[tspear]

And 500 cycles isn’t “par for the course” for lithium ion batteries. They get far more cycles out of them than that. Just my Volt battery alone was designed to go 5,000 cycles and only lose 10 % capacity.

500 cycles is the number I have seen multiple times for Li-Sulphur....

Tim

 

[Velocity173]

500 cycles is the number I have seen multiple times for Li-Sulphur....

Tim

Yeah no dispute there but the article claims that’s equivalent to a Li-ion batt. That’s not correct. You can cycle a Li-ion far more times than Li-S.

 

[flyingcheesehead]

2-The faster you charge a battery the more heat you produce. This must be dissipated to avoid damage to the battery itself and the structure around the battery.

You can also increase efficiency. What with conservation of matter and energy and all, it's pretty simple: Power out of the charger = power into the battery + waste heat. If you have an 80% efficient charging process, that means every 10kWh you push into the battery is going to turn into 8kWh of power stored in the battery and 2kWh of heat (about 6800 BTU). If you can increase the charging efficiency to 90%, you not only end up with an extra kWh in the battery, you also cut the amount of heat in half.

Easier said than done, yes, but it's all part of the design process and the tradeoffs that are chosen.

One way to resolve this problem is to develop easily changeable battery packs. Spare battery packs could be stockpiled at FBOs and charged overnight when current electrical grid usage is normally at its lowest.

Also, much easier said than done. Either all of the various electric aircraft need to use the exact same batteries (or multiples thereof), or the FBOs will have to stock a bunch of different ones. Given the cost of running an FBO, I doubt they'll want to stock a bunch of different batteries, and what happens when you get to an FBO that already gave away their last charged battery that your plane can take? Plus, what kind of equipment, training, and certification will be required for the battery swaps?

Another possibility might be developing a way to cool the batteries while charging.

Definitely. This is already done with some EVs, and I've seen some interesting patent filings for substantial cooling systems for EVs. For airplanes, it's probably better if the cooling system is ground-based so you don't have the extra weight penalty there.

I was referring to lithium batteries and their habit of lighting up at most inconvenient times if they're charged too fast or something. You won't be jumping out of the airplane to get away from some threat. Not in flight anyway.

You also won't be charging them too fast in the air.

Most of the EV battery fires have been caused by either physical damage from road debris or from charging anomalies. Neither one of those is going to happen to an aircraft in flight... And when a battery begins to overheat and you get the warning, get on the ground NOW and you should be fine... But in a crash scenario you'll almost certainly come out better with a battery than a large amount of flammable liquid.

 

[MIFlyer]

You can also increase efficiency. What with conservation of matter and energy and all, it's pretty simple: Power out of the charger = power into the battery + waste heat. If you have an 80% efficient charging process, that means every 10kWh you push into the battery is going to turn into 8kWh of power stored in the battery and 2kWh of heat (about 6800 BTU). If you can increase the charging efficiency to 90%, you not only end up with an extra kWh in the battery, you also cut the amount of heat in half.

Easier said than done, yes, but it's all part of the design process and the tradeoffs that are chosen.



Also, much easier said than done. Either all of the various electric aircraft need to use the exact same batteries (or multiples thereof), or the FBOs will have to stock a bunch of different ones. Given the cost of running an FBO, I doubt they'll want to stock a bunch of different batteries, and what happens when you get to an FBO that already gave away their last charged battery that your plane can take? Plus, what kind of equipment, training, and certification will be required for the battery swaps?



Definitely. This is already done with some EVs, and I've seen some interesting patent filings for substantial cooling systems for EVs. For airplanes, it's probably better if the cooling system is ground-based so you don't have the extra weight penalty there.



You also won't be charging them too fast in the air.

Most of the EV battery fires have been caused by either physical damage from road debris or from charging anomalies. Neither one of those is going to happen to an aircraft in flight... And when a battery begins to overheat and you get the warning, get on the ground NOW and you should be fine... But in a crash scenario you'll almost certainly come out better with a battery than a large amount of flammable liquid.

I'd imagine that changing out a user changeable batter pack would be treated as some owners as adding fuel/oil (owner can do it all with no logbook entry) whereas other owners will insist you need to hire a DER for each swap, register as experimental and repeat each time you take three toggles out and slide a new battery in place.

 

[Shuswap BC]

Make sure that they are outfitted with regenerative braking. That 3 seconds of braking action every time they land can help with the battery charging.




Make sure you read that with as much sarcasm as you possibly can muster.

 

[flyingcheesehead]

I'd imagine that changing out a user changeable batter pack would be treated as some owners as adding fuel/oil (owner can do it all with no logbook entry) whereas other owners will insist you need to hire a DER for each swap, register as experimental and repeat each time you take three toggles out and slide a new battery in place.

While it is the functional equivalent of adding fuel, the weight of the batteries means that there is likely to be some mechanical equipment necessary to lift them into place, plus securing and connecting them correctly could be a challenge.

For reference, the Bye eFlyer 2 has a 92kWh pack. I can't find any info on how much it weighs, but 8 pounds/kWh seems to be the limit with the very latest in battery technology. That's a 736-pound pack, for a two-seat trainer!

You won't be able to lift it yourself so there will need to be machinery to lift it and place it in the plane, and securing such a heavy load in place is non-trivial and will likely need some kind of special tools. The FAA doesn't tend to like non-mechanics to use tools on their airplanes at all, so I wouldn't be surprised if they required some kind of trained assistance ($$$) to do this. The electrical connection is the most easily solvable problem here, as it's reasonably easy to create a relatively idiot-proof connector.

Then, there's the practicality aspects. For my Mooney to fit its mission in a reasonable fashion, I would need 5-6 of those 736-pound packs. Even if enough airports had the equipment to allow me to replace them en route to somewhere else, it might be time-consuming enough that merely plugging in to recharge (with something resembling a Tesla Supercharger) would be a better solution anyway.

 

[3393RP]

https://spectrum.ieee.org/energywis...ims-to-double-the-range-of-electric-airplanes

OXIS has made a habit of engaging in partnerships with various electrification schemes and issuing glowing press releases, but as of today they don't have a product that will even come close to their PR hype. They haven't overcome the intrinsic short life cycle issues with recharging LiS batteries, and they're hyping vaporware.

 

[Cap'n Jack]

OXIS has made a habit of engaging in partnerships with various electrification schemes and issuing glowing press releases, but as of today they don't have a product that will even come close to their PR hype. They haven't overcome the intrinsic short life cycle issues with recharging LiS batteries, and they're hyping vaporware.

Says only you.

 

[3393RP]

Says only you.

What commercial product have they produced? Where is their technology in production? What have they built besides pouch batteries the size of an iPhone?

Their latest press release yesterday announced Sanyo will represent them in Japan. What is Sanyo going to sell?

 

[Cap'n Jack]

What commercial product have they produced?

Batteries, maybe? They've been producing them for some time now, albeit in small quantities. You need these for real-world testing.

Where is their technology in production? What have they built besides pouch batteries the size of an iPhone?

What is wrong with pouch batteries? They are used in tablets, phones, drones, electric vehicles and small personal computers. As such, pouch cells have a major market share for powering devices. It actually makes a lot of sense to use pouch cells, given the flexibility they provide for the final product design. It makes more sense to produce pouch cells at this point than any other type.

Their latest press release yesterday announced Sanyo will represent them in Japan. What is Sanyo going to sell?

Given what Sanyo produces now as part of their product line, and given what Oxis does now, my best guess is that Sanyo is going to sell batteries.

You've been predicting the imminent demise of Tesla for some time now. Hasn't happened yet, doesn't look like they are going away soon.
Now you are claiming Oxis is selling vaporware...Sanyo doesn't think so. I'm pretty sure they they know Oxis' capability far better than you. After all, Sanyo produces a variety of batteries now, including the very well regarded Eneloop brand.

If you were in charge of Li ion battery development in the 1970's you would have stopped it. 60 cycle recharge cycles, shock sensitive, prone to catching fire.