Tesla Model 3

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cricketo   1 kW

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Re: Tesla Model 3

Post by cricketo » Feb 05 2019 10:28pm

billvon wrote:
Feb 05 2019 11:37am
I'm not sure how codes would address that. "You have to have a mostly planar roof?"
For starters, code could say at least 30% of the roof surface has to be South-facing. Then indeed, they could require that South facing part of the roof doesn't have any of these features :

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Re: Tesla Model 3

Post by Punx0r » Feb 06 2019 3:52am

billvon wrote:
Feb 05 2019 6:00pm
Probably. Compare that to ~40% for the charge-discharge cycle loss.

In general, the fewer conversion steps, the better. An ICE used only at highway speeds - with electric taking care of city driving - is pretty hard to beat.
40% Round trip efficiency on a li-ion battery seems high?

Agree on the latter, this constant load/speed centred around an efficient operating point for the ICE is exactly what the series hybrid system would aim to achieve but with the additional conversion steps & losses. I was thinking more of mixed or urban driving where thermal efficiency of the ICE drops from ~30% to 10-20%, but I suppose that kind of driving is not what the ICE range extender is typically used for...

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Re: Tesla Model 3

Post by neptronix » Feb 06 2019 10:28am

cricketo wrote:
Feb 05 2019 10:14pm
neptronix wrote:
Feb 05 2019 8:34pm
ICE mechanical energy > transmission ( ~7% loss )
What does this 7% represent ? Increased friction due to gear box ? Oil pumps ? Sub-optimal engine performance due to variance in RPM ? Friction losses in the transmission ? Any difference between 2wd, 4wd, FWD, RWD ?

Also don't tell these guys :)

https://en.wikipedia.org/wiki/Workhorse_SureFly
That ~7% is friction losses in the transmission. There are multiple gears that the engine power must go through before it hits the wheels. This is the same reason that mid drive efficiency is significantly lower than what we see in hub motors ( until you go and climb a 15% grade and your hub motor falls out of it's efficiency curve in a dramatic way - in that case, the mid drive obviously wins the efficiency challenge ).

AWD and RWD significantly increases this friction figure. There is a big difference in the reported fuel economy for a FWD version of a car versus an AWD version. A couple mpg, usually - due to the fact that you have an additional a pair of 90 degree angled gear engagements.

One thing of note is that Honda's newer hybrids use a single ratio, single gear reduction from the gasoline engine to the wheels, and the electric motor provides the startup torque needed. This reduces the friction of the gasoline engine to the bare minimum and is the reason why these vehicles have fantastic fuel economy, despite their lack of the aerodynamic gifts that the Priuses have. The downside is that if the hybrid system fails, the car cannot get going from a stop.
Efficiency is everything :bolt:

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Re: Tesla Model 3

Post by cricketo » Feb 06 2019 10:40am

neptronix wrote:
Feb 06 2019 10:28am
That ~7% is friction losses in the transmission. There are multiple gears that the engine power must go through before it hits the wheels.
Understood. So for comparing against an ICE vehicle we still need to account for drop in engine efficiency due to variance in RPMs. That may be lower for a hybrid like you're describing, but even there engine won't run at steady RPMs at its peak performance.

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Re: Tesla Model 3

Post by billvon » Feb 06 2019 11:39am

Punx0r wrote:
Feb 06 2019 3:52am
40% Round trip efficiency on a li-ion battery seems high?
That's not just lithium ion charge/discharge efficiency. It's also generator efficiency, power conversion efficiency, controller efficiency and motor efficiency. Let's ballpark those numbers:

Generator efficiency 90%
Power conversion efficiency 93% (generator AC voltage to battery charge DC voltage)
Battery POWER (not coulombic) efficiency 90%
Motor controller efficiency 95%
Motor efficiency 90%
Powertrain efficiency 95%

Overall 61% efficiency (39% loss.)

Now, you can do a lot to get around those numbers. For example, you can throttle the engine up and down to closely match the power requirements at the wheels - that way the battery isn't being charged or discharged much so you gain that 10% back. But that's what you have to do for direct-to-wheels anyway.
--bill von

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Re: Tesla Model 3

Post by billvon » Feb 06 2019 11:41am

cricketo wrote:
Feb 06 2019 10:40am
Understood. So for comparing against an ICE vehicle we still need to account for drop in engine efficiency due to variance in RPMs. That may be lower for a hybrid like you're describing, but even there engine won't run at steady RPMs at its peak performance.
I would note that since most hybrids don't use standard transmissions, the engine RPM is largely uncoupled from the wheel RPM. So you can run at a more efficient speed, rather than a ratio to vehicle speed.
--bill von

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Re: Tesla Model 3

Post by Punx0r » Feb 07 2019 4:19am

Are those efficiency values typical? I would have expected ~95% for alternator & motor and 98-99% for battery charger and motor controller based on industrial equipment, but appreciate a vehicle may be different - especially for the motor operating over a wide range of speeds.

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Re: Tesla Model 3

Post by billvon » Feb 07 2019 11:30am

Punx0r wrote:
Feb 07 2019 4:19am
Are those efficiency values typical? I would have expected ~95% for alternator & motor and 98-99% for battery charger and motor controller based on industrial equipment . . .
It depends what you are quoting and how. For example, a lithium ion battery might well have a 99% coulombic efficiency (amp-hours in to amp-hours out) but a 90% power efficiency (watts in to watts out) since you have to charge at a higher voltage than you discharge. If you are charging at 4 volts and discharging at 3.6 volts, that's 90% right there. (Lower charge rates result in greater efficiencies.)
--bill von

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Re: Tesla Model 3

Post by Punx0r » Feb 08 2019 4:12am

Good point :thumb:

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Re: Tesla Model 3

Post by Ianhill » Feb 08 2019 4:47am

Temperature makes a big difference with ice engines too, Cold air is more dense and needs more fuel to reach it's stochmetric value of 15-1 so the Injectors have to work harder and throw more fuel in. This then means you get more power per stroke but your efficiency drops with worse thermal loss in the block.

Like climbing pikes peak ice engines struggle and very rarely are in ideal conditions to make max power it's a juggling game that's just not there with electric motors but batterys they are more sensitive to heat but less so altitude but from my understanding alitiutue does affect range due to pressure within the cell but by how much or little to compare I'm unsure.

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Re: Tesla Model 3

Post by billvon » Feb 08 2019 12:08pm

Ianhill wrote:
Feb 08 2019 4:47am
Temperature makes a big difference with ice engines too, Cold air is more dense and needs more fuel to reach it's stochmetric value of 15-1 so the Injectors have to work harder and throw more fuel in. This then means you get more power per stroke but your efficiency drops with worse thermal loss in the block.
Mostly agreed. But the primary efficiency loss isn't due to "thermal loss" - it's due to pumping losses. When it's cold out, air is denser, so the throttle plate has to remain more closed for the same mixture - and it is harder to pump air past the narrower opening.
--bill von

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Re: Tesla Model 3

Post by Ianhill » Feb 08 2019 1:33pm

billvon wrote:
Feb 08 2019 12:08pm
Ianhill wrote:
Feb 08 2019 4:47am
Temperature makes a big difference with ice engines too, Cold air is more dense and needs more fuel to reach it's stochmetric value of 15-1 so the Injectors have to work harder and throw more fuel in. This then means you get more power per stroke but your efficiency drops with worse thermal loss in the block.
Mostly agreed. But the primary efficiency loss isn't due to "thermal loss" - it's due to pumping losses. When it's cold out, air is denser, so the throttle plate has to remain more closed for the same mixture - and it is harder to pump air past the narrower opening.
If you dont mind me asking bill how you learnt all this random information ?

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Re: Tesla Model 3

Post by billvon » Feb 08 2019 2:06pm

Ianhill wrote:
Feb 08 2019 1:33pm
If you dont mind me asking bill how you learnt all this random information ?
That particular tidbit came from working with Ford on their VCC110 program. I was working for a subcontractor but worked with their engineers quite a bit - and they were looking at both EV's and hybrids, and looking at ways to optimize both. Understanding where ICE engines were most efficient was critical for optimizing hybrids.
--bill von

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Re: Tesla Model 3

Post by Ianhill » Feb 08 2019 2:50pm

billvon wrote:
Feb 08 2019 2:06pm
Ianhill wrote:
Feb 08 2019 1:33pm
If you dont mind me asking bill how you learnt all this random information ?
That particular tidbit came from working with Ford on their VCC110 program. I was working for a subcontractor but worked with their engineers quite a bit - and they were looking at both EV's and hybrids, and looking at ways to optimize both. Understanding where ICE engines were most efficient was critical for optimizing hybrids.
That gives good reasoning to all this juicy info I read of yours then, all my ev knowledge comes from potching about with stand on scooters or the ice side ive only learnt from reading and building a basic turbo track car, my main college was for electrical installation so I knew a bit of the language and a bit about older type motors, I've learnt more outside of college than in and I'm only 33. It's costs to much for me to further my education.

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Re: Tesla Model 3

Post by Punx0r » Feb 09 2019 5:35am

The avoidance of pumping losses is one of the reasons diesel engines are generally more efficient than spark-ignition ones like petrol/gasoline. Although a solution to this is valve-throttled engines that use variable valve lift instead of a throttle plate are supposed to give up to a 10% efficiency gain. The Fiat 500 multi-air is probably the most common car with this system.

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Re: Tesla Model 3

Post by Ianhill » Feb 09 2019 7:55am

Punx0r wrote:
Feb 09 2019 5:35am
The avoidance of pumping losses is one of the reasons diesel engines are generally more efficient than spark-ignition ones like petrol/gasoline. Although a solution to this is valve-throttled engines that use variable valve lift instead of a throttle plate are supposed to give up to a 10% efficiency gain. The Fiat 500 multi-air is probably the most common car with this system.
Like the freevalve system used in the agera, I looked into the past of rover uk and they had a patent for a electrically controlled hydraulic actuated valvetrain back in the 90's and developed it over a few years then flopped.

They never had direct injection so im guessing they struggled obtaining the air fuel ratios with fuel coming out of suspension in the runners and limiting them getting higher compression ratios with knock happening and having issues with emissions to the funding dried up they were just a little to early shame.

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Re: Tesla Model 3

Post by Punx0r » Feb 09 2019 8:24am

That was the "VVC" variant of the Rover K-series engine. It allowed infinitely variable timing and duration (when the valve opens and for how long) but could not vary lift (how much the valve opens), which is what makes valve throttling possible. If you're interested there's more information on how it works here: http://www.sandsmuseum.com/cars/elise/t ... e/vvc2.pdf

Gasoline Direct Injection is another thing entirely that allows spark ignition engines to run high compression ratios than would otherwise be possible by removing the opportunity for detonation (knock) to occur. Greater compression ratio is the other factor that makes diesels more efficient and also gives a nice boost to power. It's a big win for the format of low-capacity, high-boost turbocharged petrol engines that are increasingly popular both for powering pure-ICE cars and for hybrid vehicles due to their small size, low weight and greater efficiency.

I think we're getting off topic now though as the Model 3 is a pure BEV 8)

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Re: Tesla Model 3

Post by Ianhill » Feb 09 2019 9:07am

I had a k series vvc in a 825kg metro then the later 1.8 turbo unit at 200bhp in same car thing was a rocket 13 second quarters and economic 40mpg.
This patent was from camcon and powertrain limited working for mg rover with a camless engine back in 2001 it was developed before that but they took it Detroit that year for investment and failed.

I just like it as a hobbie and learning a few new things outside of my education, I'd like to do a few extra course really can never know to much or get bored of learning.

Back on electric check out thunderfoots battery video what a condescending tosser most of his past videos make sense but seems he got an elon chip lately and making himself look a fool.

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Re: Tesla Model 3

Post by billvon » Feb 09 2019 12:20pm

Punx0r wrote:
Feb 09 2019 8:24am
That was the "VVC" variant of the Rover K-series engine. It allowed infinitely variable timing and duration (when the valve opens and for how long) but could not vary lift (how much the valve opens), which is what makes valve throttling possible.
I would add that the Prius uses an Atkinson cycle engine. It is not a "true" Atkinson in that the piston always moves the same distance regardless of position in the four-stroke cycle. Instead, Atkinson operation is obtained by leaving the intake valve open for too long; some of the charge is ejected before the intake valve closes, resulting in a small volume of mixture compressed followed by a large expansion during the power phase. Variable valve timing allows operation in both Atkinson mode (most of the time) and conventional 4-stroke operation during wide open throttle operation (for maximum power.)

Since Atkinson cycle engines are more thermodynamically efficient but less powerful, the throttle plate has to be open wider at moderate power settings - thus reducing pumping losses.
--bill von

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Re: Tesla Model 3

Post by TheBeastie » Feb 19 2019 11:09am

Electrek.co the home for the Super hardcore Tesla lovers has put out negative news about Tesla.
Considering Tesla love to exaggerate on dates etc I personally find it quite alarming that Tesla would even be honest about any kind of date on the 35k M3, but it appears Tesla was willing to do just that by removing any promised availability date.

Tesla has been promising its standard Model 3 battery pack to bring the price of the vehicle down to the long-awaited $35,000 price, but now Tesla has removed any mention of the base model from its website – sending some fans into a panic.
https://electrek.co/2019/02/18/tesla-st ... ans-panic/
Speed Kills Range, 10mph = 46 miles range, 20mph = 20 miles, 30mph = 8 miles rangehttps://goo.gl/1JNL53
Over Charging Kills ur battery bit.ly/1hzWKl4
Consider PAS as your only throttle https://goo.gl/Kg1F8F
Fuel-Cell is the ultimate battery coupled with 4th-gen Nuclear
https://goo.gl/TcKtHs https://goo.gl/ZhFFot https://goo.gl/gfa215
10 Square Miles of solar panels = 0.12GW average power! https://goo.gl/Ub1S39

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Re: Tesla Model 3

Post by Ianhill » Feb 19 2019 1:33pm

As a company tesla has alot of customer relations to sort out, in the UK they are rated bottom of the satisfaction table of all cars and on reliability terms each vehicle spends around 1 week per year at a service centre that's 7× the average service time for a car that doesn't brake down due to less moving parts ? While the leaf is one of the most reliable cars be it electric or petrol.

One problem we have is range people say its not an issue but every electric car is sold on its capable range and we don't see that with ice cars as the infrastructure around the car make it meaningless, we need to top up electric like this to be able to dominate the entire market be it large small or suv.

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Re: Tesla Model 3

Post by raylo32 » Feb 20 2019 7:42am

I don't see how the charging infrastructure can ever be as ubiquitous as gasoline stations, especially here in the USA. Think of a busy Interstate highway with literally thousands and thousands of gas pumps and you still have to wait to access one sometimes. So even if you were to replicate those thousands of pumps into charging outlets (utilities will have to seriously upgrade generating and distro lines for that), each fill takes at least 20x the time it takes to pump gas. How does that work? Lines will be into the next county. Not to mention the vast empty stretches of our country... good luck electrifying that. These pure electrics cars are great and I do see a role for them as local commuters that can charge at home and/or workplace every day. But beyond that, not so much.

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Re: Tesla Model 3

Post by TheBeastie » Feb 20 2019 11:57am

I was just browsing around on Youtube and checked out CNBC's Youtube Channel, lots of videos frequently uploaded on Tesla which often gets views..

This video was just uploaded to CNBC's Youtube Channel hours ago, what I couldn't believe what this fund manager believes Tesla's share price will be worth..
She says it will be worth about $700 a share in a bear case in 5 years, and about $4,000 a share in 5 years in a bullish case..
LOL, I think that's just crazy. Good luck with your investment everybody. :thumb: :bigthumb: :kff: :bolt:
Now people can't say I didn't post something positive on Tesla/Elon Musk.
https://www.youtube.com/watch?v=aEiaah3Oki4
Speed Kills Range, 10mph = 46 miles range, 20mph = 20 miles, 30mph = 8 miles rangehttps://goo.gl/1JNL53
Over Charging Kills ur battery bit.ly/1hzWKl4
Consider PAS as your only throttle https://goo.gl/Kg1F8F
Fuel-Cell is the ultimate battery coupled with 4th-gen Nuclear
https://goo.gl/TcKtHs https://goo.gl/ZhFFot https://goo.gl/gfa215
10 Square Miles of solar panels = 0.12GW average power! https://goo.gl/Ub1S39

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Re: Tesla Model 3

Post by raylo32 » Feb 20 2019 12:12pm

I totally agree. Tesla makes some nice vehicles but they have a long way to go to catch up to the major manufacturers in being able to build cars efficiently and economically. And Tesla doesn't have any really special proprietary technology that the majors can't at least equal. I don't see Tesla's cult status holding up long term.
TheBeastie wrote:
Feb 20 2019 11:57am
I was just browsing around on Youtube and checked out CNBC's Youtube Channel, lots of videos frequently uploaded on Tesla which often gets views..

This video was just uploaded to CNBC's Youtube Channel hours ago, what I couldn't believe what this fund manager believes Tesla's share price will be worth..
She says it will be worth about $700 a share in a bear case in 5 years, and about $4,000 a share in 5 years in a bullish case..
LOL, I think that's just crazy. Good luck with your investment everybody. :thumb: :bigthumb: :kff: :bolt:
Now people can't say I didn't post something positive on Tesla/Elon Musk.

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Re: Tesla Model 3

Post by billvon » Feb 20 2019 12:38pm

raylo32 wrote:
Feb 20 2019 7:42am
I don't see how the charging infrastructure can ever be as ubiquitous as gasoline stations, especially here in the USA. Think of a busy Interstate highway with literally thousands and thousands of gas pumps and you still have to wait to access one sometimes.
Right. Now count the number of outlets available in a typical mall - each capable of level 1 charging.

The big advantage of EV charging over gas usage is that power lines already run everywhere, so adding charging stations is easy (at least at first.) And no big excavation projects for tanks, or environmental hassles from spills, and much less risk of fire. No real estate needed; no land to buy or rent, no curbs to cut, no new asphalt to pour. Just existing parking spaces. And once you start to hit the limits of the grid infrastructure, the upgrades needed are well-understood and common.
So even if you were to replicate those thousands of pumps into charging outlets (utilities will have to seriously upgrade generating and distro lines for that), each fill takes at least 20x the time it takes to pump gas. How does that work? Lines will be into the next county.
I am one of the EV coordinators for my company, and we solved most of the charging problems by putting a simple outlet at each EV parking spot. Outlets are $0.61 each. Even with the conduit, wiring, breaker additions etc the total cost was about $100 per parking spot. People get to work, plug in, and don't think about it until they leave - and they get ~40 miles of range during that time. So for the most part there won't be lines; there will be people looking for parking spots, which people are used to now. (There will still be lines for fast chargers for people taking long trips, but these are the exception rather than the rule.)

But thinking about how to put chargers along malls, highways, businesses etc in the same numbers as gas pumps sort of misses the point. Gas cars can't be refueled at your house. EV's can be. Most people are going to do most of their charging at home, using a grid system already set up to deliver ~20kW to each home. And they are going to tend to do this when power is cheap (at night) - which is the time that the grid is seeing the lowest load currently. So it will be a long time before any grid upgrades are needed for that.
Not to mention the vast empty stretches of our country... good luck electrifying that. These pure electrics cars are great and I do see a role for them as local commuters that can charge at home and/or workplace every day. But beyond that, not so much.
Tesla has put a fast charging station every ~100 miles across most major highways in the US. (https://www.tesla.com/findus) That covers long trips. But again, most people won't use that sort of charging for their everyday driving.
--bill von

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