At this point, rated miles are no longer that useful. We should really have efficiency compared at 70 or 75 mph. The X and the Bolt's 70-75 mph efficiency is different from the S, so charging speed in terms of miles should be done at a realistic DCFC jump scenario instead of EPA 5 cycle rating. Unfortunately, Idaho National Labs AVT is likely to lose a lot of funding and automotive journalists thus far have not been up to the task.
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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
At this point, rated miles are no longer that useful. We should really have efficiency compared at 70 or 75 mph. The X and the Bolt's 70-75 mph efficiency is different from the S, so charging speed in terms of miles should be done at a realistic DCFC jump scenario instead of EPA 5 cycle rating. Unfortunately, Idaho National Labs AVT is likely to lose a lot of funding and automotive journalists thus far have not been up to the task.
Rated miles are definitely still useful. If one car has 25% better rated efficiency than another, using only kWh as a measuring stick would be short-sighted.
My Bolt was picked up by my shipper with just 40 miles on the GOM (~16% charge). The dealer was slammed with Bolts (and Volts) at the end of the year, so was not able to put my Bolt on a charger before the shipper showed up. I could have waited an extra day for them to charge up my Bolt, but I wanted it on the truck ASAP so I said forget it.
First thing after it arrives in MD will be a 15 mile drive to the nearest Chargepoint CCS station. There is an evGo charging station just a couple of miles from me, but I don't want to mess with their 30 min auto shutoff....I hear that might be the cause for the decreased charging rates that one Bolt owner blogger experienced after the initial 30 min charge was over.
The Chargepoint station doesn't have any auto-shutoff points AFAIK. I should be able to get good data for a straight 10% to 80% charge.
If GM would simply provide a readout for the voltmeter and ammeter, then the public would face the challenge of: V * A * [hours] = KWHs which is easily charted on a sheet of graph paper.
'Rated' always seems to be a shell game of one sort or another.
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'Rated' always seems to be a shell game of one sort or another.
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I am saying that the rating needs to change. Rated miles uses EPA 5 cycle and that doesn't reflect the concerns of long distance BEV owners. We need a new set of ratings... a 75 mph cruising at 75 degrees, no HVAC and another at 70 mph, 25 degrees ambient with heat set to 70 degrees. These two likely encompass the actual range concerns (higher temps with AC is a lower power drain than cold).
It will be interesting to get one of these on a larger charger. The later portion of the curve prior to the 50% drop off is about 45kW, and that implies the voltage was approaching the 365V range (which is about halfway between his starting voltage of 330V and an assumed 400V @ 100%SoC).
If so, that appears current limited with a 125A charger. On a 200A unit (80kW), that would imply it could draw ~72kW peak, about a 1.2C charge rate. If the car cant accept greater than 125A charging, then it would seem that even 50kW chargers wouldn't be used to their full potential... and limited to about a 0.72C rate (assuming a 62kW battery, as I've seen surmised).
If the car won't do up to 80kw, One wonders why... pack chemistry? Wire gauge? Cooling capability?
WannabeOwner
Well-Known Member
Rated miles is not standard even when you ignore km. There are two popular range calculations which vary a lot. The American spec is the most pessimistic.
Most pessimistic == least optimistic. Most of us can routinely exceed the EPA number in mild weather without getting shot at from road rage. Or we can cut the EPA range in half if we want.
JohnSnowNW
Active Member
Most of us can get much lower numbers than EPA estimates by simply driving with the rest of traffic.
Even with the US spec being the most pessimistic, its accuracy with real world Hwy conditions is poor. It's just not as poor as NEDC.
In my experience, the EPA estimate is fairly close to steady state driving in the 65-70 mph range in moderate weather on my X.
Range goes down rather rapidly above that...
FWIW, I did a road trip in my VOLT recently (MD to CT), and on the leg to CT, I was booking it at 75 mph on the highway the whole way. Ended up with a gas-only MPG of 32.5
On the return trip (with about 400 pounds of extra people/cargo in tow PLUS a hitch-mounted cargo box), I traveled 65 mph the whole way. I got 38 mpg on the return trip.
So obviously, that 10 mph difference between 65 and 75 makes quite the difference. 18% gain in MPG despite the extra payload and the cargo box on the back by going 65 vice 75. Only a 300 foot height elevation difference between MD and CT, so that is pretty much negligible.
JohnSnowNW
Active Member
I've never really been able to drive a steady 65-70 on the interstate. I have to speed up and slow down pretty regularly due to traffic (typical I would wager when driving around large cities), and I get buffeted by vehicles/semis driving in a similar fashion.
My opinion is that the test needs be designed how people typically drive, and that isn't at a steady rate on an empty, still, summer morning, in California.
In principle, that's a fine idea. The challenge is that "how people typically drive" varies widely, even within a region.
It's pretty easy to measure a vehicle and say it takes 300 Wh/mile at 65 mph and 350 at 75, etc.
It's hard to say whether the way you drive on a Sunday afternoon in heavy traffic will match a given test profile.
Which is why what I think I'd like to see added to the EPA data sheets is just steady state speeds on flat land in moderate weather for 55-85 mph. The rest will be interpolation anyway, so no point in designing a complicated profile that matches one person well and another badly.
The EPA Range estimate is a combination of separate city and highway estimates and, thus, the combined estimate is not intended to estimate highway range. (sounds obvious writing it out...) The "rated" ranges quoted above are I think in relation to Tesla rated range which I thought mimics this combined "EPA Range" number. A steady ~65mph typically does match the EPA Range energy consumption, but again it's the EPA Highway Range that is intended to predict typical ranges on US highways.
For reference, here are the EPA Range (combined) and EPA Highway Ranges for a few cars, in miles:
X 90D: 257 & 263
S 90D: 294 & 303
S 60D: 218 & 227
Bolt EV: 238 & 217
i3 (94BEV): 114 & 102
IONIQ Electric: 124 & 110
You'll note that the Teslas have HIGHER Highway range than the combined values. The others have LOWER highway range than combined value. This because the Teslas are both more aerodynamic and heavier than the others.
Either way, the EPA Highway range is a better metric when you're trying to assess real-world highway driving efficiency. If we make some guesses about usable battery capacity, we can determine the expected energy consumption of the cars to match the EPA Highway range.
X 90D: 86 kWh / 263 mi = 327 Wh/mi
S 90D: 86 / 303 = 284
S 60D: 62 / 227 = 273
Bolt EV: 60 / 217 = 276
i3 94: 27 / 102 = 264
IONIQ: 28 / 110 = 254
This expected highway energy efficiency is what I'd like to see published. We have Highway EPA Fuel Economy data, in units of MPGe, but that includes charging losses.
For reference, here are the EPA Range (combined) and EPA Highway Ranges for a few cars, in miles:
X 90D: 257 & 263
S 90D: 294 & 303
S 60D: 218 & 227
Bolt EV: 238 & 217
i3 (94BEV): 114 & 102
IONIQ Electric: 124 & 110
You'll note that the Teslas have HIGHER Highway range than the combined values. The others have LOWER highway range than combined value. This because the Teslas are both more aerodynamic and heavier than the others.
Either way, the EPA Highway range is a better metric when you're trying to assess real-world highway driving efficiency. If we make some guesses about usable battery capacity, we can determine the expected energy consumption of the cars to match the EPA Highway range.
X 90D: 86 kWh / 263 mi = 327 Wh/mi
S 90D: 86 / 303 = 284
S 60D: 62 / 227 = 273
Bolt EV: 60 / 217 = 276
i3 94: 27 / 102 = 264
IONIQ: 28 / 110 = 254
This expected highway energy efficiency is what I'd like to see published. We have Highway EPA Fuel Economy data, in units of MPGe, but that includes charging losses.
The problem is that the EPA highway test has an average speed of 48 mph, and a peak of 60 mph.
It doesn't do a good job of predicting the effect of higher drag on the high freeway speeds folks like to drive these days.
That's why I'd like to see the higher fixed speed grids added to the EPA data.
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