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Chevy Bolt - 200 mile range for $30k base price (after incentive)
- Thread starter FredTMC
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- bolt chevy Electric Vehicles review
JohnSnowNW
Active Member
Color me surprised that CR set up a test that would favor Tesla's competitor, then waited until the clicks died down to give a partial explanation of the results/testing methodology.
CR is a division of Dyson Industries. "Nobody sucks more!" is their motto.
However, they are another data point that the Bolt commonly exceeds it's EPA combined range.
Their Tesla data is useless. Not done in Range Mode, and regen should be a factory default. Both cars should have been driven the same, ie - in pack formation far enough apart so aero effect is nil.
However, they are another data point that the Bolt commonly exceeds it's EPA combined range.
Their Tesla data is useless. Not done in Range Mode, and regen should be a factory default. Both cars should have been driven the same, ie - in pack formation far enough apart so aero effect is nil.
SageBrush
REJECT Fascism
"Our EV range test involves some mixed driving."
CR, is that really the best you can do ?
Teslabjorn recently got stranded in his X after it quit on him with 14 km left on the GOM... think he said something about battery cell imbalance. Not sure what the final verdict was, but he's driving around a Leaf currently...
JohnSnowNW
Active Member
Fair, though his vehicle is high mileage (<100,000 km) for its age (1 year), and many of those miles have been towing a trailer back-and-forth across Norway.
Sigh... that isn't much of a follow up unfortunately.
Here's two key points from Consumer Reports:
- We put our EVs into their less-aggressive regenerative braking mode; regenerative brakes help EVs recapture some of the energy lost in braking. Many EVs have a mode with aggressive regenerative braking that’s meant to capture more of that energy, but it can be an intrusive experience, making the brakes seem grabby, especially for drivers who are new to EVs.
- Our EV range test involves some mixed driving, but much of it is done by driving a constant 65 mph on highways. If drivers were to meander on rural roads at 45 mph, for example, they might get even more range.
CR didn't clarify if they drove to the point of towing the car or not. Their description doesn't sound like they drove it down all the way. Most reviewers don't... they drive it down a lot of the way and then use the efficiency stats provided by the car. The problem with that approach is how much the stats can be swung by driving style including the use of regen.
And 65 mph is not fast at all and likely just below the the speed where the Model S is more efficient than the Bolt. In all other respects, the Bolt is going to be more efficient... more efficient acceleration, more efficient deceleration, more efficient at lower speeds. But at 75 mph, steady state, the Model S is likely more efficient. And when driving on the highway for long distances, that makes a big difference.
A Model S 75D has 72.6 kWh of usable capacity. CR's tests managed 235 miles, or 309 Wh/mile. That's terrible. Here's my 2013 P85 on a 24 mile round trip, most of it done at 65-70 mph and zero net altitude difference:
That corresponds to 293 miles of range if my pack was new... .and it isn't. Of the ~12.5 miles each way, about 3 miles was not highway and a lot of that was 35-45 mph with stop lights in the city/burbs. My AC is on at 74 degrees and the outside temp was 82. So if I can achieve 263 Wh/mi in an old P85, what exactly did CR do? So when CR states "much of it is done by driving a constant 65 mph on highways" just what does that mean? In my energy graph above, you can see where I accelerated to 70 mph uphill (energy spike near 20). Then it was mostly 65 mph until I get into the city and I stop. The next big spike is again the acceleration onto the highway and then uphill... not particularly trying to be energy efficient there. Some of the highway was done at 75 mph. Comparing to the 75D in the CR test, my P85's EPA efficiency is 89 MPGe combined and the 75D has a 103 MPGe or 15% more efficient than my car. Getting over 300 Wh/mi on a "mixed driving" circuit, much of it at 65 mph is terrible.
There is a substantial difference in efficiency if one allows the Model S to fully leverage regenerative braking. The difference is easily a reported 275 Wh/mi versus 325 Wh/mi in my car. I'd love to see the actual route and power consumption chart of CR's test. If they didn't drive to the point of shut down and merely used the reported efficiency stats, without full regen, they'd have a very different result.
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Final verdict is what would happen to any BEV at very low SOC. A big power draw will cause the voltage to sag low enough to abruptly cause the vehicle to decide the pack is below the minimum voltage threshold and shut down the pack. Since he was towing, that was even easier to achieve. The cells were very well balanced, especially since Bjorn does a lot of full pack cycles and often charges high enough to cause the top balancing circuits to kick in.
SageBrush
REJECT Fascism
Sounds like they didn't account for hysteresis? The fact that gauges need time to settle. The obvious programmer's choice would be a warning and a taper to limp mode.
I can pull a bunch of amps from a battery and watch the voltage sag to under the minimum threshold during the load. But the instant I kill the load, it returns to nominal.
You are not going to brick a battery by allowing the voltage to fall under the low window under load. If you let a battery rest static below the low voltage value for hours, yeah, you're going to screw it up.
SageBrush
REJECT Fascism
A couple mile MPH is a big difference. At 65 mph the Tesla estimate approaches 260 miles range. The CR drive cycle is being misconstrued as a 65 mph test when it most definitely is not.
But more importantly, CR decides to ignore the obvious: The Tesla happily jumps from Supercharger to Supercharger while the Bolt sits for hours at some lousy CCS station ... if it is lucky. Otherwise the owner calls a tow truck.
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Remember, this is already at very low SOC... the vehicle was only showing 14 miles of range anyways. Maybe the software doesn't take into account the towing and shut down too early.
stopcrazypp
Well-Known Member
I noticed the same thing. It offers a bit more insight (like how they disabled regen on the Tesla), but still not htat useful. I guess it reconfirms this was not done at steady 65mph, but still doesn't tell us how much mixed driving was done. Even a rough percentage number (10%? 50%?) would have been useful.
SageBrush
REJECT Fascism
For a publication founded on transparency, CR has fallen into disrepute.
To summarize:
The test has an undisclosed city portion wherein they hobble the Tesla by turning off part of the regen functionality and then the media and GM/bolt echo box try to construe the results as a 65 mph test.
Bloody ridiculous.
I would write to the editor but I gave up on CR a couple of years ago
My interpretation is that their test protocol is a deliberate secret. Under pressure, they let a few details slip out but the reader is basically supposed to trust them. Obviously many readers don't.
Thinking about it more, there is no way they drove the 75D or the Bolt to exhaustion. That's because whatever circuit they chose has to work with shorter range BEVs in order to provide the consistency they are trying to get but failing miserably. It is actually very difficult to to proper range testing on real streets... variations of weather, traffic patterns, and so forth can have significant effects. That's why the EPA testing is done on a dyno and synthetically corrected for additional factors like aerodynamics. That way the tests are repeatable. The other way is to run it on closed loop circuits doing laps like Idaho National Labs does and record steady state speeds.
CR's testing on surface streets is subject to a lot of driving style variations. As it turns out, I had to make a ~60 mile round trip last night and so I tried with regen set to normal and set to low. The difference in regen effect is significant as it plays with the Wh/mi average. With low regen, there are fewer really big negative numbers to average into the range calculations. At highway speeds, normal regen can do 60 kW. In low regen, the max is 30 kW and low enough that the brake lights never kick in. At lower speeds, the low regen is almost imperceptible and friction brakes are used all the time. That messes greatly with the Wh/mi average, especially if they are aiming for "normal" driving style and not hyper-miling as they stated. That easily pushes the Wh/mi estimation well over 300 Wh/mi.
I suspect CR used something like a 50 mile test loop, something they can do repeatedly with all kinds of BEVs. They then use the consumption as reported by the vehicle in order to estimate the total range. It isn't just the city driving, what is really important for that range estimator is the regen off the highway. Let say the 50 mile test loop is 40 miles of highway... which is pretty close to what I drove last night (26 out of 29 miles is highway). The Wh/mi while on the highway was over 300 Wh/mi, but then with full regen, it dropped significantly. Without full regen, it didn't drop nearly as much. If they drove the car to exhaustion, the difference wouldn't be that big... but without doing that, the acceleration onto the highway isn't balanced by the regen on the other side so the Wh/mi is too high. Of course, the further you drive, the less of an effect this has, but one has to drive a lot for the average to balance out.
Therefore, this change alone can account for 15-20% difference, especially if they didn't drive the vehicles to immobilization. The rest of the difference can easily be highway versus city driving. Again, the Bolt is more efficient at lower speeds and acceleration/regen, but the Model S is more efficient at higher speeds.
Again, the real test is taking both on DCFC trip jumps as that is when range really matters. Being able to drive 230 or 250 miles at 0-40 mph in city/suburban traffic is not particularly interesting. For example, simulate driving from D.C. to Orlando, or LA to SF, both very common driving patterns that require back to back charging at DCFC EVSE's and driving at normal traffic speeds. That's 65 mph to 75 mph speed limits most of the time. I would choose testing at 75 mph, because the speed limit is often that fast in many places and traffic typically flows even faster than that.
CR's testing on surface streets is subject to a lot of driving style variations. As it turns out, I had to make a ~60 mile round trip last night and so I tried with regen set to normal and set to low. The difference in regen effect is significant as it plays with the Wh/mi average. With low regen, there are fewer really big negative numbers to average into the range calculations. At highway speeds, normal regen can do 60 kW. In low regen, the max is 30 kW and low enough that the brake lights never kick in. At lower speeds, the low regen is almost imperceptible and friction brakes are used all the time. That messes greatly with the Wh/mi average, especially if they are aiming for "normal" driving style and not hyper-miling as they stated. That easily pushes the Wh/mi estimation well over 300 Wh/mi.
I suspect CR used something like a 50 mile test loop, something they can do repeatedly with all kinds of BEVs. They then use the consumption as reported by the vehicle in order to estimate the total range. It isn't just the city driving, what is really important for that range estimator is the regen off the highway. Let say the 50 mile test loop is 40 miles of highway... which is pretty close to what I drove last night (26 out of 29 miles is highway). The Wh/mi while on the highway was over 300 Wh/mi, but then with full regen, it dropped significantly. Without full regen, it didn't drop nearly as much. If they drove the car to exhaustion, the difference wouldn't be that big... but without doing that, the acceleration onto the highway isn't balanced by the regen on the other side so the Wh/mi is too high. Of course, the further you drive, the less of an effect this has, but one has to drive a lot for the average to balance out.
Therefore, this change alone can account for 15-20% difference, especially if they didn't drive the vehicles to immobilization. The rest of the difference can easily be highway versus city driving. Again, the Bolt is more efficient at lower speeds and acceleration/regen, but the Model S is more efficient at higher speeds.
Again, the real test is taking both on DCFC trip jumps as that is when range really matters. Being able to drive 230 or 250 miles at 0-40 mph in city/suburban traffic is not particularly interesting. For example, simulate driving from D.C. to Orlando, or LA to SF, both very common driving patterns that require back to back charging at DCFC EVSE's and driving at normal traffic speeds. That's 65 mph to 75 mph speed limits most of the time. I would choose testing at 75 mph, because the speed limit is often that fast in many places and traffic typically flows even faster than that.
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