Trip to LA, 265 miles down, 175 miles back

[samiam95124]

Ok, I don't really understand this one. My estimated range from driving around the city went to 265 miles. We got to LA after leaving fully charged with one charging stop, that I spent time on to get a full charge (DCFC). On the way back we charged 3 times while on the road. After full charge overnight at L2, today it reads 175.

I would have thunked that you get better range on the open highway. Why the big range loss?

Thanks,

Scott

 

[SparkE]

A simple google search will find you the answer, in detail.

In short, the faster you go, the higher the wind resistance, and that kills mileage (both gas and electric).

Driving any car at 40 mph non-stop and the same car at 70 mph, will give much worse mileage (m/g, or m/kWh) at 70 mph.

That is why the range estimate was lower - it based it on your 'recent' driving, which consumed more kWh per mile.

 

[SeanNelson]

I would have thunked that you get better range on the open highway.

That's true in vehicles with an Internal Combustion Engine because on the highway you don't have all those starts, stops and idling that really kill your fuel economy in the city. But an EV recovers most of its stopping energy for starting again, and it wastes almost no energy "idling". So the result is that an EV has very little penalty for city driving, and that means that the added air resistance you get at highway speeds actually outweighs the slight benefit of constant speed.

 

[DucRider]

I would have thunked that you get better range on the open highway.

That's true in vehicles with an Internal Combustion Engine because on the highway you don't have all those starts, stops and idling that really kill your fuel economy in the city. But an EV recovers most of its stopping energy for starting again, and it wastes almost no energy "idling". So the result is that an EV has very little penalty for city driving, and that means that the added air resistance you get at highway speeds actually outweighs the slight benefit of constant speed.

The exceptions being the Tesla Model S and X.
Both have higher EPA range for hwy than city.
The low CD and high mass are big factors.

 

[SeanNelson]

I would have thunked that you get better range on the open highway.

That's true in vehicles with an Internal Combustion Engine because on the highway you don't have all those starts, stops and idling that really kill your fuel economy in the city. But an EV recovers most of its stopping energy for starting again, and it wastes almost no energy "idling". So the result is that an EV has very little penalty for city driving, and that means that the added air resistance you get at highway speeds actually outweighs the slight benefit of constant speed.

The exceptions being the Tesla Model S and X.
Both have higher EPA range for hwy than city.
The low CD and high mass are big factors.

I wonder if less efficient regen might also be a factor?

 

[samiam95124]

Well, I am in line for the Tesla M3 and will be making the same trip, so yes, there will be a comparison. One thing for sure, if it takes driving 50MPH to LA to save "range" that a non-starter. With charge time, the trip to LA is already slow enough.

 

[Anonymous]

Ok, I don't really understand this one. My estimated range from driving around the city went to 265 miles. We got to LA after leaving fully charged with one charging stop, that I spent time on to get a full charge (DCFC). On the way back we charged 3 times while on the road. After full charge overnight at L2, today it reads 175.

I would have thunked that you get better range on the open highway. Why the big range loss?

Thanks,

Scott

Could you be a little more specific?

My drive back from Santa Cruz through Watsonville (Hwy-1), Hollister (Hwy 129 to 101 to 25 to 156), the Pacheco Pass (Hwy 152) to Hwy-99 and down through the Grapevine (I-5) was estimating at 270 when I stopped in Delano for the DCFC one charge that I needed to make it to Hancock Park (Los Angeles) (I-5 to Hwy 170 to US 101) that trip.

 

[cruftbox]

My experience with longer drives is that higher speeds, 70+ really start to drain the battery more significantly and drop your range.

The display shows estimated ranges based on recent driving habits.

When I did an LA to Cambria drive (with a CCS charge in Solvang), at first I was shocked to see that the estimated range with a full charge was ~175 miles.

What I learned was that my driving at 80+ MPH speeds really cut down my range and got the car to show me what my range would be like if I drove like that again.

On the way home, I kept the speed down, and literally saw the total range increase as we got closer to home. Meaning, when we got home, I had 30 more mile showing in range left, compared to what the initial range number predicted I would have left.

Now I take the range numbers with a grain of salt and look at the bars on the left, which show the actual percentage or charge, regardless of mileage.

 

[Anonymous]

Now I take the range numbers with a grain of salt and look at the bars on the left, which show the actual percentage or charge, regardless of mileage.

I watch the amount of KWh used as against a full 60 and considering the topography of the remaining trip can do my own calculation of miles remaining.

It is much more accurate!

 

[vrpratt]

While my wife has only had her Bolt for three weeks I've had my Toyota Mirai for a year and during the following six months evolved the following brain-dead rule for forecasting its MPGe on a perfectly flat and straight road, namely going up I-5 after the grapevine has flattened out. I call it the 57-75 rule. If you maintain a steady 57 mph (actual according to the GPS, which on the Mirai is 59 on the speedometer) you will get a steady 75 MPGe. Conversely at 75 mph you will get a steady 57 MPGe. (And at 66 mph I believe it's close to 66 MPGe though I haven't checked that as thoroughly.)

It would be interesting to hear from users of flat portions of I-5 how the Bolt does at 57 and 75 mph, and at nearby speeds. Is there a simple counterpart for the Bolt of my 57-75 rule for the Mirai?

(For any form of energy a Ge (lower-case e) is defined as exactly 33.7 kWh, close to 121.3 MJ. For hydrogen energy a Ge or gallon-equivalent is within a percent or so of a kg of hydrogen. The EPA city mileage for the Bolt is 128 MPGe corresponding to 128/33.7 = 3.80 miles per kWh around town. The high Cd of the Bolt, 0.32 vs. 0.29 for the Mirai, reduces this considerably for highway driving, so staying in the truck lane in order to go at whatever the truck in front of you is traveling at will help a lot with mileage without drafting and without making people mad at you.)

Regen on FCVs like the Mirai and the Honda Clarity is comparable to that on hybrids like the Toyota Camry on account of their tiny (1.6 kWh or so) batteries. 60 kWh batteries or more like on all Teslas and the Bolt have a far lower internal resistance whence there is much less I^2R loss during regeneration and use of the battery. Hills therefore should have considerably less impact on BEVs than on FCVs, though measuring this with any meaningful accuracy is difficult compared to perfectly flat roads due to the variability of hilly roads.

 

[GetOffYourGas]

While my wife has only had her Bolt for three weeks I've had my Toyota Mirai for a year and during the following six months evolved the following brain-dead rule for forecasting its MPGe on a perfectly flat and straight road, namely going up I-5 after the grapevine has flattened out. I call it the 57-75 rule. If you maintain a steady 57 mph (actual according to the GPS, which on the Mirai is 59 on the speedometer) you will get a steady 75 MPGe. Conversely at 75 mph you will get a steady 57 MPGe. (And at 66 mph I believe it's close to 66 MPGe though I haven't checked that as thoroughly.)

Interesting observation. Typically when we talk about MPGe, it is wall-to-wheels (which is what matters for cost of energy). In other words, the EPA MPGe rating you see on the Monroney sticker includes charging losses. If you only consider battery-to-wheels (which is what determines your driving range), the car will be more efficient. So when you refer to MPGe here, to be clear, what are you basing your calculation on? I assume that it is battery-to-wheels, based on something the car reports?

Regen on FCVs like the Mirai and the Honda Clarity is comparable to that on hybrids like the Toyota Camry on account of their tiny (1.6 kWh or so) batteries. 60 kWh batteries or more like on all Teslas and the Bolt have a far lower internal resistance whence there is much less I^2R loss during regeneration and use of the battery. Hills therefore should have considerably less impact on BEVs than on FCVs, though measuring this with any meaningful accuracy is difficult compared to perfectly flat roads due to the variability of hilly roads.

These smaller batteries also operate at a lower voltage. Since P = I * V, the same regen power requires more current. And since the internal losses are proportional to I^2, that is where your loss on the Mirai is really coming from.

I really enjoy your view comparing the Mirai to the Bolt. Not many people have to opportunity to live with both. Keep them coming!

 

[Anonymous]

The manual states that in order to get optimum miles you need to travel at 50 miles per hour or less. Highway driving is mire like 70. Also, there is very little regent with highway driving compared to city driving. In town I might leave home with 150 miles and return later in the day with the same 150. On my last highway trip I was able to go 240 miles on a full charge. You are right about the level 3 chargers. It took 3 1/2 hours to get a full charge. The manual and advertising for fast charging states 30 min, empty to full. Not realistic.

 

[GetOffYourGas]

The manual and advertising for fast charging states 30 min, empty to full. Not realistic.

Not so. GM states "90 miles in 30 minutes" and "238 miles per charge". Very clearly NOT stating "30 min, empty to full".

The 90 miles in 30 minutes is possible, under ideal conditions, for a particular starting/ending SoC.