$1 billion BMS Ooops...

On Thursday, February 25, 2021 at 12:34:46 PM UTC-8, Dan Marotta wrote:
Oh that is so last decade. I've got an InMotion V11 instead, and the
bruises to prove it!

Dan
5J
On 2/25/21 10:32 AM, Tango Eight wrote:
Now, where did I leave my Segway...

Electric unicycle that's adventurous as one of us old folks.... oh remembers Dan has a gyrocopter... :-)

On Thursday, February 25, 2021 at 10:50:46 AM UTC-6, kinsell wrote:
On 2/25/21 9:01 AM, Hank Nixon wrote:
On Wednesday, February 24, 2021 at 4:42:01 PM UTC-5, wrote:
https://insideevs.com/news/490300/hy...ll-82000-bevs/
Discus amongst yourselves...

The market wants:
Fast charge for convenience
Safety
Long life for low cost of ownership
It is possible to get the send two if one compromises on the first.
Can't have all.
Balancing packs requires time.
Unbalanced packs fail or die sooner.
Reality
UH

Just reading about the Lilium electric air taxi in Forbes, they want to
draw 1.2 megawatts from the batteries for 60 seconds for vertical
takeoff and transition to forward flight.

You can do that sort of thing for 3 seconds in a Tesla for Ludicrous
mode, but 60 seconds can fry the batteries in the air taxi.

Tesla has 4000 small cylindrical cells, with a manifold in contact with
all of them, with pumped liquid cooling to allow high charge and
discharge rates.

Most electric gliders just use big pouch cells, a lot of people just
don't understand the implications of that.

Lilium has raised 400 odd million bucks in funding, looking more like a
pipe dream all the time. Ditto for that Alice thingie, but they've only
burned 200 mil.
Right on, Dave. I want to see just one of these pipe-dream machines get a standard airworthiness cert. with the OK for carrying passengers, just one. Just like fusion power (and Trump's healthcare plan), it's only a short few years away, I guess.

Right on, Dave. I want to see just one of these pipe-dream machines get a standard airworthiness cert. with the OK for carrying passengers, just one.

- I know of one being close. Look up Joby.

Just like fusion power (and Trump's healthcare plan), it's only a short few years away, I guess.

- Kamala has a health plan for you Herb.
Unfortunately, You and Me as white males only get to pay for it, but Hey now!
It's a true realization of Marx&Engel's dreams and it covers the entire Central America.

Best,
GK

On 2/25/2021 9:28 PM, G K wrote:
- I know of one being close. Look up Joby.

https://www.youtube.com/watch?v=4wbF...ture=emb_title

An uncontained battery failure is as bad as an uncontained engine failure (car, airplane, or glider). Any potentially unstable battery like most Lithium chemistries should be in a safety container that will either contain or exhaust the fire, explosion, or heat. I would feel a lot better if the batteries were in a sealed stainless box with appropriate vents to the outside of vehicle.
Wit HZ

On 2/27/2021 11:25 AM, wrote:
An uncontained battery failure is as bad as an uncontained engine failure (car, airplane, or glider). Any potentially unstable battery like most Lithium chemistries should be in a safety container that will either contain or exhaust the fire, explosion, or heat. I would feel a lot better if the batteries were in a sealed stainless box with appropriate vents to the outside of vehicle.
Wit HZ

I feel a bit nervous about carrying a "USB power bank" in the glider,
which includes a not-tiny lithium battery of the dangerous type. As for
the yuuuge batteries needed for electrically propelled gliders, I think
I'd wait for safer battery chemistry. LiFePO4 batteries are a lot
safer, and their energy density - and price - are being improved so that
they can compete with other types of lithium batteries. They are
already used in some electric cars.

Moshe Braner wrote on 2/27/2021 8:48 AM:
On 2/27/2021 11:25 AM, wrote:
An uncontained battery failure is as bad as an uncontained engine failure (car, airplane, or
glider). Any potentially unstable battery like most Lithium chemistries should be in a safety
container that will either contain or exhaust the fire, explosion, or heat. I would feel a
lot better if the batteries were in a sealed stainless box with appropriate vents to the
outside of vehicle.
Wit HZ

I feel a bit nervous about carrying a "USB power bank" in the glider, which includes a not-tiny
lithium battery of the dangerous type.* As for the yuuuge batteries needed for electrically
propelled gliders, I think I'd wait for safer battery chemistry.* LiFePO4 batteries are a lot
safer, and their energy density - and price - are being improved so that they can compete with
other types of lithium batteries.* They are already used in some electric cars.

You should look at the Jonkers JS3 RES electric self-launcher using LiFePo batteries. It's the
only one I know of using that kind of battery.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Eric,

I think that is probably a typo mistake, the voltage range and capacity is typical for 3000-3500 mAh li-ion cell.

wrote on 2/27/2021 1:19 PM:
Eric,

I think that is probably a typo mistake, the voltage range and capacity is typical for 3000-3500 mAh li-ion cell.
It's a bit awkward to drill down to it, so here's a short cut. Go to this page:
https://jonkersailplanes.co.za/res-system/

Then scroll to the section with this:


Battery specification

Battery type EMECTRIC 96-4 400V
Battery configuration 96S4P LiFePo
Battery Voltage 270V-400V
Capacity per battery 4.7kWh
Battery Weight: 22kg (48.5 lbs)
Maximum number of batteries 2

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Wednesday, 24 February 2021 at 14:42:01 UTC-7, wrote:
https://insideevs.com/news/490300/hy...ll-82000-bevs/
Discus amongst yourselves...
Some comments:

- High current draw for VTO launches (Lilium) - IIRC they are planning to use supercapacitors to provide the current boost so that the batteries don't have to. A supercapacitor/LiPo combination makes a lot of sense for that problem.

- Electric vs. gas: a very experienced motorglider ferry pilot, who I am sure does not want to be named, once told me when discussing Stemmes: "I've had every known Stemme issue except the in-flight fire, I'm not looking forward to that one..." I side with Eric here - we have normalized all the hassle that goes with gas self-launchers. When we get mature technology electric self-launchers, they'll dominate. Current complaints about electric sound exactly like the complaints about electric cars, before Tesla got it right.