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Discussion Starter #1 (Edited)
Video of a media session about the Bolt held at the LA auto show. Lots of info, most we've heard. Mando DC fast charging stations in order to become a Bolt certified dealer is semi-new.

Also, Tavel said he was browsing the "Volt owners site"....had to be a reference to this place! Said he was reading a thread about the Bolt regenerative braking..... probably that huge one Norton started. Lol

Most interesting to me was when he started talking about DC fast charging.....said that "80 kW allows 90 miles in 30 minutes". Was that a simple goof on the fast charging rate (assumed to be 50 kW), or did he mistakenly give away the Bolt's max DC charge rate......the one the Bolt was engineered to support?

He knew all the other figures like the back of his hand, so makes me think he wouldn't screw up the fast charging rate like that.....

If you are reading this Josh, feel free to come in! We won't tell anyone. :p


edit: autocorrect is horrible
 

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I see no reason the Bolt wouldn't be able to charge at an 80 kW rate for the first 40% SOC (that's about the same rate the Model S60 used to). We knew that the charge would taper, but the question was when and by how much.

Not that I have 80 kW charging available on my route yet, but if that is true, it would change the dynamic about how I take my trips.
 

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Simple math and common sense tell us that he misspoke.

The Bolt is rated at 0.283 kWh/mile. (33.7 kWh/gallon / 119 MPGe)

50 kW * 0.5 hr / 0.283 kWh/mile = 88 miles... close enough to 90.

80 kW, even if you assumed some tapering, would be way more than 90 miles in 30 minutes.

And AFAIK, there still aren't even any public CCS chargers faster than 50kW, are there?

(I still hope that GM has "future-proofed" Bolts to accept >50kW charge rates once those chargers get rolled out, but I wouldn't bet the farm on it.)
 

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What specifically would GM needed to change to allow the Bolt to charge at 80 kW vs 50 kW? Is this just hardware, software or battery or all three.
 

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Discussion Starter #5
Simple math and common sense tell us that he misspoke.

The Bolt is rated at 0.283 kWh/mile. (33.7 kWh/gallon / 119 MPGe)

50 kW * 0.5 hr / 0.283 kWh/mile = 88 miles... close enough to 90.

80 kW, even if you assumed some tapering, would be way more than 90 miles in 30 minutes.

And AFAIK, there still aren't even any public CCS chargers faster than 50kW, are there?

(I still hope that GM has "future-proofed" Bolts to accept >50kW charge rates once those chargers get rolled out, but I wouldn't bet the farm on it.)
He definitely misspoke. But where did that 80 kW figure come from? Did he just completely butt fumble the 2017 Bolt's DCFC charge rate?
Or did he say 80 because he had the Bolt's theoretical max DC fast charging rate on the brain (the max rate the Bolt was engineered to support), and let that slip by mistake? Because as the chief engineer, he would know that number quite well. He was able to spit out all kinds of other numbers with no issues later in his speech.

If I'm not mistaken, he was also the one that let slip the Bolt's 235 mile range (eventually ended up 238) to The Fast Lane Car guys at CES at the beginning of the year.
http://www.hybridcars.com/chevrolet-reportedly-said-at-ces-the-bolt-has-235-miles-range/
 

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What specifically would GM needed to change to allow the Bolt to charge at 80 kW vs 50 kW? Is this just hardware, software or battery or all three.
Well, there's 3 bits:
- Charging port and cabling
- Battery's ability to support 1.3r C charging without significant degradation
- Software control of power
 

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Discussion Starter #7 (Edited)
What specifically would GM needed to change to allow the Bolt to charge at 80 kW vs 50 kW? Is this just hardware, software or battery or all three.
Tavel said in a previous interview the Bolt was being engineered to support higher than 50 kW DCFC just in case (so I assume the wiring is already in place in addition to the battery being able to take up to 80 kW). In that case, a software update is probably all that would be needed.
 

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I would guess the cooling system is the limiter based on the C rate of the Spark EV charging.

Without higher powered CCS stations, the point is moot. In theory Chargepoint will install a 125kW class charger in the near future.
 

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I think he misspoke but the mistake was based on the Bolt EV's supported charge rate. There have been hints of this before from other engineers, so not a total surprise. I suspect we will know soon enough because we will see higher power CCS chargers in the near future.

I would guess the cooling system is the limiter based on the C rate of the Spark EV charging.

Without higher powered CCS stations, the point is moot. In theory Chargepoint will install a 125kW class charger in the near future.
I suspect you noticed that some of the DFFC chargers being installed for the CA electric highway will be stubbed for higher power charging.
 

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When I wrote to the State of California about the Mojave Corridor project, I asked about security and charging rates. I said that 24kW Chargepoint facilities I have seen are unacceptable. Too slow, too dangerous at night for women.

Here's the response:

Good afternoon xxxxx and the xxxxx Family,


My name is Brian Fauble and I am the team leader for the “DC Fast Chargers for California’s Interregional Corridors” solicitation.


I was forwarded your email regarding your concern on the award to ChargePoint for the Mojave Express Corridor leading to Las Vegas.


The 24-kw stations that ChargePoint has previously installed was in partnership with BMW as their effort to install fast chargers on corridors. I assume that BMW chose to go with the smaller fast charging stations because their vehicles have the smaller capacity, but that is just an assumption.


For our solicitation we did not set a power requirement because not every site in California can handle the exact same power load capacities and we did not want to limit the applicants from choosing their sites.


For the I-15 corridor, ChargePoint under this award will be installing at least (2) DC fast charging stations with both CHAdeMO and SAE connectors with a minimum charging rate of 50-kW, (1) dual-port 7.7-kW level 2 charging station, (2) stub outs for future installations, security cameras and lighting at every site along the corridor.


ChargePoint also stated that they plan to install their newest DC fast charging station, once it completes its UL certification, in place of their 50-kW stations. These new DC fast chargers are capable of dispensing up to 125-kw per charging port.


Regarding the cost of charging at each station, we at the Energy Commission do not have any authority to regulate the cost of charging. Charging costs are determined by either the site host, the owner of the equipment, or the equipment provider that is managing the equipment.


I hope this information has eased your concern, and if you have any additional questions or concerns please feel free to contact me.


Thank you,


Brian Fauble, Associate Energy Specialist

Zero-Emission Vehicle and Infrastructure Office

California Energy Commission
 

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Discussion Starter #11
Interesting. I'm really curious what the Bolt will take in if one plugs it into one of these 125 kW stations....that hopefully isn't as rare as an ice cream pooping unicorn!
 

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My favorite quote was at the beginning by Steve Majoros - not about the Bolt specifically but about GM's corporate attitude:

Humble and hungry
This bodes well for GM and its break-through products like the Bolt going forward. A sound mantra for other less-self-disciplined-and-focused corporate and political leaders to consider adopting.
 

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Finally got to watch the whole video.
Once again Josh showed his graph of various ways of getting regen.
The graph shows, what I believe is, just taking your foot off the Go Pedal and coasting in Drive.

And once again, no mention of what happens when a normal driver THEN presses the Brake Pedal to slow down a little more.
How high is the 'Blended Brakes' / Brake Pedal regen rate?

Why is this guy and Chevy marketing avoiding talking about 'Normal Driving in Drive'?
I don't believe they are doing themselves any favors going on and on about 'This Regen and That Regen'.

This is an advanced feature that is NOT available on a Tesla and some other EV brands!
 

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Simple math and common sense tell us that he misspoke.

The Bolt is rated at 0.283 kWh/mile. (33.7 kWh/gallon / 119 MPGe)

50 kW * 0.5 hr / 0.283 kWh/mile = 88 miles... close enough to 90.

80 kW, even if you assumed some tapering, would be way more than 90 miles in 30 minutes.

And AFAIK, there still aren't even any public CCS chargers faster than 50kW, are there?

(I still hope that GM has "future-proofed" Bolts to accept >50kW charge rates once those chargers get rolled out, but I wouldn't bet the farm on it.)
Simple math says that from an engineering standpoint he spoke correctly, but it may be software limited to 50KW charging. I don't see why they would bother putting a software limiter on charge rate, it would be like putting a 200 mph speed limiter on a Honda civic. If 50KW charging stations are the only ones available you advertise your car as capable of 50KW even if it is really capable of more to avoid having a lawsuit because you "lied" about charging rates.

From data gathering on YouTube from when 120KW superchargers first became available in Europe and video of S60 charging on 120KW capable supercharger, the Tesla 60kWh battery charge rate maxes out at 88KW for the first few minutes until it reaches 10% SOC where the charge rate has already tapered to 75KW.

It takes the Tesla S60 (old school S60, not the "software limited" S75) 28 min to reach 50% SOC from a starting point of 3% SOC, and around that point it is charging at 50KW, so remaining charge time would be approximately equal to any other car charging at 50KW. To do the same charge from 3% to 50% (28kWh) in the Bolt (if it is limited to 50KW the whole time) would take about 35 min. So, we loose a whole 7 min compared to an S-60 at a 120KW capable supercharger, and an 80% charge would take about an hour and 5 min vs 55 min for the S-60... is it even worth quibbling over 75KW vs 50KW in the Bolt?

If I didn't lose you with the data above, this boils down to the Bolt probably being easily capable of 80KW charging if the battery chemistry is similar to Tesla battery chemistry, and that going above 75KW charging gains you virtually nothing... and that going from 50KW to 75KW only gets you a time savings of 10 min or so going from virtually dead to 80%. This is all based on starting from an almost flat battery. If you have 50% charge or more you get no advantage from using a charging station with more than 50KW of charging available.

All of this changes when you have larger battery sizes. The Tesla 120KW superchargers are aimed at Tesla's with battery packs larger than 60kWh, and if other mainstream auto makers start making cars with large battery packs then CCS charging stations will need to upgrade their capabilities to match.

Keith

PS: With a Bolt on a 50KW charger this would give you a gain of 42.9% in 30 min, or 102 miles of EPA combined driving range... I suspect that the 90 miles in 30 min is based on starting at a higher SOC than in the estimates above.
 

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If I didn't lose you with the data above, this boils down to the Bolt probably being easily capable of 80KW charging if the battery chemistry is similar to Tesla battery chemistry, and that going above 75KW charging gains you virtually nothing... and that going from 50KW to 75KW only gets you a time savings of 10 min or so going from virtually dead to 80%.
Yeah, pretty much this. The real limit is the size of the battery pack not the CCS charger. Given that Qinsp has so kindly provided the letter from the California Energy Commission which indicates that the Charge Point CCS chargers will be 125 kW, we should get to test this in the near future. LOL

FYI the chemistry used by Tesla is not the same as used by LG Chem.
 

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It has to be cooling or the Spark EV would only handle 17kW. Exceeding the operation temperature window of a battery kills it's lifespan.
 

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If 50KW charging stations are the only ones available you advertise your car as capable of 50KW even if it is really capable of more to avoid having a lawsuit because you "lied" about charging rates.
I suspect this is exactly what's going on. It's like computer manufacturers who quoted maximum capacities of "12GB" of memory because they had six DIMM slots and the largest memory modules that were available at the time only held 2GB each - even though the system was engineered to work with 4GB modules when they eventually became available.
 

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I think that part of the issue is that we are not using the same language. I believe that GM's marketing material is referring to a 50 kW average rate over the course of an hour (~160 miles... ~40kWh @ ~4 miles/kWh), and Josh Tavel might be referring to an 80 kW peak rate. An 80 kW peak rate still won't provide 100 miles in 30 minutes because it should start tapering the charge shortly after starting. It would be nice if the member who was making all the charge graphs came back and edited his graphs to start at 80 kW charge rate. If correct, we could get a very good idea of the charge cycle and the rate at which it tapers off (assuming the battery is 80% SOC after one hour and an average rate of charge of 50 kW).

For me, it won't make a huge difference until they finish upgrading the chargers along the route I drive. Currently, they are only 60 kW chargers, so I wouldn't be able to test or verify what the peak charge rate is at any given SOC.
 

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I think that part of the issue is that we are not using the same language. I believe that GM's marketing material is referring to a 50 kW average rate over the course of an hour (~160 miles... ~40kWh @ ~4 miles/kWh), and Josh Tavel might be referring to an 80 kW peak rate. An 80 kW peak rate still won't provide 100 miles in 30 minutes because it should start tapering the charge shortly after starting. It would be nice if the member who was making all the charge graphs came back and edited his graphs to start at 80 kW charge rate. If correct, we could get a very good idea of the charge cycle and the rate at which it tapers off (assuming the battery is 80% SOC after one hour and an average rate of charge of 50 kW).

For me, it won't make a huge difference until they finish upgrading the chargers along the route I drive. Currently, they are only 60 kW chargers, so I wouldn't be able to test or verify what the peak charge rate is at any given SOC.
I think you're referring to my battery models. I'm don't know how to update the Bolt EV model based solely on this comment by Tavel. I think he simply misspoke and am ostensibly waiting on bro1999's real DCFC charging results. ;) (I don't expect anymore details from GM.)

But I'd speculate that 80kW charging would provide more than 100 miles in 30 minutes, using tapering extrapolated from other battery models. Starting at 0% SoC it might regain as much as ~130 miles in 30 minutes using some very hand-wavy assumptions.
 
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