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My Chevy volt suffers much less than my tesla’s - never quite figured that out.
I don't have data on that leakage. Could be a material or sleep current (software) difference.
Tesla uses Lithium Nickel Cobalt Aluminum Oxide battery.
They picked this due to lower price, higher density. Its drawback is the lower runaway temperature (not as safe).
Chevy Volt has Lithium Nickel Manganese Cobalt Oxide battery.
It is more expensive but more safe. It also has longer life.
Interesting comparative analysis by the UCS below. 2009 EVs vs 2016 EVs vs the best EVs. The data does not take embodied energy in the battery itself into account, so the MPG numbers calculated are significantly higher than previously calculated and only approachable if you drive an EV for many miles (which leads to more total pollution). The results illustrate the dramatic regional differences clearly, also how power grid emissions are changing very rapidly (and while this is a 2018 study the grid data is already 2 years old).
Elsewhere in the study they state they've calculated a 7 mpg increase from 2017 to 2018 (73 mpg for the national average to 80 mpg). Despite the massive jump in solar in California where many EVs live (and the 80 mpg number is sales weighted) a 10% improvement in just one year seems hard to reconcile. Link
This makes an interesting point- a good ICE was much more competitive on a C02 basis against an EV just a few years ago, but changes in both the grid and cars in the last ~2 years have made it much less so today. In fact looking back we'll likely find that today's EVs are actually significantly better than we're calculating now (once 2018 grid data is available).
Thank you for the data. I like the way that they include the 24h discharge. I guess temperature is the most optimal 75 deg F. And the car maker provides the most efficient home charger system to them (their interest). Also interesting to see how the battery size and annual miles driven change the efficiency of an EV.
The "charge cords" (EVSEs) provided by most manufacturers in North America are typically limited to 12 amps, and come with 120v plugs. The chargers themselves, which are built into the cars, at worst can support 15-16 amps at 240v. So the car makers do not provide the most efficient setup. They provide something that "works" in most homes without overloading a potentially poorly maintained electrical system.
Teslas UMCs do a lot better. They have adapters available to fit a variety of different receptacles, and automatically set the max amperage accordingly. The older UMC can support up to 40 amps @ 240v. The newer UMC can support up to 32 amps @ 240v. Depending on year and configuration, the charger capacity in the car itself is anywhere from 40 amps to 80 amps. So it might be possible to max out the charger with the UMC or might not. (This will change when the 'Medium Range' and 'Short Range' Model 3s hit the streets - as they will only have 32 amp charging.)
Now another fun part. Owners report different charging efficiency for the same setup. Not sure where the variance comes from though. Search for images for Teslafi and check the charging efficiency numbers.
Here you can see the efficiency of different charging stations (ignore the home charging number): https://teslamotorsclub.com/tmc/posts/1718944/
The regular public chargers were from 90%-96% and the supercharger (from multiple sources) at 97%-99%
Home charging between 80%-94% https://teslamotorsclub.com/tmc/posts/2072089/
This makes me thinking that the EPA charging efficiency is somewhere around 94% (best home charging) so someone can be more efficient on a supercharger or less efficient at home...
Home charging could range anywhere from 8 amps at 120v (about 1 kW) to an enthusiast with an older dual charger Tesla running 80 amps at 240v (about 20 kW).
The typical Chargepoint-like charging station that you'll see in the wild at a shopping mall or workplace typically supports 16- to 30-amp charging at 208v (a three-phase power thing). So somewhere between 3.3 and 6.6 kW.
Superchargers bypass the cars internal charger and slam DC straight into the battery pack at as much as 115 kW. The actual charging electronics reside in a big cabinet nearby - fed with 277/480v three phase power.
Now consider that there is some overhead during charging. Powering up the electronics in the car, running cooling pumps as needed to keep the charger and battery temps reasonable, as so on. Could be as much as, say, 2-300 watts. This is a pretty significant efficiency hit if you are only charging from a 120v receptacle at 8 amps (1 kW). Over 20% of the power you draw from the wall is simply burned up in overhead. However if you are charging at 10 kW (which is what I do anyway...) the overhead is much less significant. At Supercharger speeds, it is a nit.
In various EV forums you'll read postings from folks who don't drive a lot state that 120v charging is fine for them. But really, some form of 240v charging gives a much better experience. Especially with a car that has a large battery pack.
The "charge cords" (EVSEs) provided by most manufacturers in North America are typically limited to 12 amps, and come with 120v plugs. The chargers themselves, which are built into the cars, at worst can support 15-16 amps at 240v. So the car makers do not provide the most efficient setup. They provide something that "works" in most homes without overloading a potentially poorly maintained electrical system.
Teslas UMCs do a lot better. They have adapters available to fit a variety of different receptacles, and automatically set the max amperage accordingly. The older UMC can support up to 40 amps @ 240v. The newer UMC can support up to 32 amps @ 240v. Depending on year and configuration, the charger capacity in the car itself is anywhere from 40 amps to 80 amps. So it might be possible to max out the charger with the UMC or might not. (This will change when the 'Medium Range' and 'Short Range' Model 3s hit the streets - as they will only have 32 amp charging.)
Home charging could range anywhere from 8 amps at 120v (about 1 kW) to an enthusiast with an older dual charger Tesla running 80 amps at 240v (about 20 kW).
The typical Chargepoint-like charging station that you'll see in the wild at a shopping mall or workplace typically supports 16- to 30-amp charging at 208v (a three-phase power thing). So somewhere between 3.3 and 6.6 kW.
Superchargers bypass the cars internal charger and slam DC straight into the battery pack at as much as 115 kW. The actual charging electronics reside in a big cabinet nearby - fed with 277/480v three phase power.
Now consider that there is some overhead during charging. Powering up the electronics in the car, running cooling pumps as needed to keep the charger and battery temps reasonable, as so on. Could be as much as, say, 2-300 watts. This is a pretty significant efficiency hit if you are only charging from a 120v receptacle at 8 amps (1 kW). Over 20% of the power you draw from the wall is simply burned up in overhead. However if you are charging at 10 kW (which is what I do anyway...) the overhead is much less significant. At Supercharger speeds, it is a nit.
In various EV forums you'll read postings from folks who don't drive a lot state that 120v charging is fine for them. But really, some form of 240v charging gives a much better experience. Especially with a car that has a large battery pack.
Missing some data?
Nissan Leafs are available with internal 6.6kW chargers, i.e. ~ 30 amps on a 220/240V dual phase with a 40 breaker. Many Leafs can use 100 amp DC charging at 500 volts via a CHAdeMO port,
which connects directly to the LI battery and is monitored/controlled via comm lines in the CHAdeMO connector by the Leaf's battery ECU (BMS). The DC charging charging is tapered as the
SOC approaches 100%. The Chevy Bolt has very similar charging capabilities. EVGO provides chargers with high current DC charging compatibility for both Leafs & Bolts as does ChargePoint.
Nissan Leafs are available with internal 6.6kW chargers, i.e. ~ 30 amps on a 220/240V dual phase with a 40 breaker. Many Leafs can use 100 amp DC charging at 500 volts via a CHAdeMO port,
which connects directly to the LI battery and is monitored/controlled via comm lines in the CHAdeMO connector by the Leaf's battery ECU (BMS). The DC charging charging is tapered as the
SOC approaches 100%. The Chevy Bolt has very similar charging capabilities. EVGO provides chargers with high current DC charging compatibility for both Leafs & Bolts as does ChargePoint.
All true. I was trying to illustrate some of differences in charging efficiency in different environments, rather than provide a complete picture of the EV charging space. Admittedly, as a Volt and Model 3 owner, I have a bit of a GM and Tesla bias in my examples. (I also still own an old Porsche too. )
The whole tapering thing at L3 charging levels is really important for optimal travel time on road trips too. But that seems like a different discussion.
All true. I was trying to illustrate some of differences in charging efficiency in different environments, rather than provide a complete picture of the EV charging space. Admittedly, as a Volt and Model 3 owner, I have a bit of a GM and Tesla bias in my examples. (I also still own an old Porsche too. )
The whole tapering thing at L3 charging levels is really important for optimal travel time on road trips too. But that seems like a different discussion.
What puzzled me is that the same people reported very different charging efficiencies on the same car at home. Found some answers:
"Looking at my own car with Gen 2 chargers and data from Teslafi.com, it seems I get about 92-93% efficiency when charging at 24A 240V (NEMA 14-30 dryer outlet) but only ~73% efficiency when charging off 120V @ 12A."
"I found you have to collect data for a significant period of time to get a good average because from day to day you get quite a variation in the number.... My numbers are consistent with others I have seen reported, so yours are in the ballpark if by something less than 80% you mean close to 80%. I use a NEMA 14-50 at 40 amps."
"In the past year of monitoring (energy meter @ panel + car readings) I've ranged 51-97% efficiency.
My efficiency will vary based on the ambient temperature at time of charging, the temperature of the battery pack when charging starts and the charge time / amount.
In the dead of winter I have observed 6A @ 240V going into my car for 10 mins with little/nothing going to the battery. The charger allows 40A, but the car only "requests" 6A since the battery is too cold to charge and the power is going to the inductive heater to warm the battery. When this happens I assume that little is going into the battery since the app / car predicts +48 hours to charge, but once the car starts pulling 40A the estimate drops to 1 hour. Obviously for small top ups (<5KWh charge) at cold temps inefficiency will be horrible i.e. 50%.
Likewise in higher temps, power has to be diverted to cool the battery, especially if charging at higher amps. (charge at SuC on hot day and listen to the AC scream!)"
The whole tapering thing at L3 charging levels is really important for optimal travel time on road trips too. But that seems like a different discussion.
It (tapering) is also a function of the battery heating that occurs while charging the result of the I^2 R losses where R is the internal resistance of the battery.
For example when charging at 100 amps with a battery resistance of 100 milliohms (.100 ohms) on a hot day, the power loss in the battery becomes 1000 watts.
This becomes critical for vehicles, e.g. the Leaf, where on-board battery temperature control is lacking.
With regard to the internal battery resistance and battery heating, this becomes a critical factor in racing for an BEV. Typical average battery currents can easily exceed
150 - 200 amps, resulting in significant battery heat during a race limiting the race vehicle's track time even with battery thermal management.
Jason Fenske at Engineering Explained did a related video just recently. Brings up some very good and verifiable figures to counter some of the anti-EV arguments. And while this is part of a series done in part with Formula E, and he recently had a Leaf loaned to him, based on his history, the dude is an analytical engineer without agenda. So I trust his numbers without verifying his sources...which he provides for full disclosure.
Ok. I'm not too happy with the recent findings about EPA's kWh/mile measurement.
The initial 24 hour soak period according to the SAE J 1634-2012 (got updated in 2017 which I can't access) is not a self-discharge period. It is for charging and for temperature control. Temp should be between 68F and 86F.
They get a used car (4k+ miles), put it on a dyno. AC, radio and lights are off. There are 3 coefficients for the dyno. One constant, one proportional to speed, one proportional to the square of speed. So I guess the dyno provides the corresponding resistance at speeds?? Then they fully deplete the battery using different driving cycles. They calculate the kWh/mile and divide the number by 0.7 to compensate for consumers and temperature. I wonder how accurate it is (before the 1/0.7 compensation).
https://www.wardsauto.com/engines/to...beyond-hybrids
... In developing the engine, Toyota boosted thermal efficiency to 36%. The 8NR-FTS was adopted for the Auris hatchback in April 2015.
Producing 241 hp and 258 lb.-ft. (350 Nm) of torque in most models, Toyota says the Euro 6-compliant engine can achieve 37 mpg (6.3 L/100 km). In developing the engine, Toyota boosted thermal efficiency to 36%. The 8NR-FTS was adopted for the Auris hatchback in April 2015. Toyota says the 1.2L 4-cyl. also achieves thermal efficiency of 36%.
Jason Fenske at Engineering Explained did a related video just recently. Brings up some very good and verifiable figures to counter some of the anti-EV arguments. And while this is part of a series done in part with Formula E, and he recently had a Leaf loaned to him, based on his history, the dude is an analytical engineer without agenda. So I trust his numbers without verifying his sources...which he provides for full disclosure.
I enjoyed that too - its straight forward - large EVs are resource hungry - I looked at the current situation where I live and the only Tesla vehicle that made sense was the Model 3 (and thats when one excludes price, powerwalls and panels).
The vehicle solution has always been very small EVS - think SMART car small - allbeit with a limited range. However, buyers want their cake and they want to eat it and moreover don't want to pay the full economic price. Then again, this should be no surprise given that many are happy to use a smartphone and aluminium cased laptop and yet look away at where the product is manufactured - Designed in California, indeed The irony is delicious
apparently this is an OK but mostly underwhelming effort from Audi - it might be harder than it looks to waltz in take on Tesla - we'll see - but the 1st salvo (1,000 units, sheesh 1 day's Model 3 production)
"…just buy that Tesla Model X 75D…"
After reading all of this, I hope it's clear that the Audi e-tron is certainly competent and will not be alien or unfamiliar to anyone who's a fan of the brand's other SUVs. It's not a car for everyone, but it's not trying to be. With a production capacity of 200 a day at the factory in Belgium, I'm pretty sure Audi will be able to sell every one it builds—it had no problem finding buyers for the 999 First Edition US-market vehicles in just one hour, after all. Which I think we can all agree is probably a good thing, if the goal is more BEVs on the road and fewer carbon emissions in the atmosphere.
apparently this is an OK but mostly underwhelming effort from Audi - it might be harder than it looks to waltz in take on Tesla - we'll see - but the 1st salvo (1,000 units, sheesh 1 day's Model 3 production)
First. Model 3 is nowhere near 1000/day production. In the last couple of weeks they were below 4000/week.
Second. the " just buy that Tesla Model X 75D" comment was made based on the higher energy consumption of the E-tron. The author however forgot to add that they were driving in the 75-87 mph range. So the efficiency is in the range of the Model X. I expect that the consumption will be just slightly higher since Audi didn't give up the look of the car on the benefit of air drag. And it has more content that consumes more power in general.
11-09-2018, 01:55 AM
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