Bolt winter performance, an ICE comparison

[mwk]

My family of four drove up to Freeport ME and back on December 31st, when it was about 9F, and we still got that range.

Thanks for the data point, Neil. This is exactly what I was talking about. My range meter suffers from short-trip syndrome too. I rarely drive more than 5-10 miles before shutting the car off. This means that the car cools down and requires the heater at full power to heat back up. My range meter often shows 100 miles or fewer lately in the expected range on a full charge. But I have no doubts that I could get on the highway and drive for at least 140 miles (sadly, the distance to the nearest CCS charger that matters to me).

Ha. OK then, I guess I can try this weekend and take that 100 mile round trip and see what happens. If I don't make it back, who here can I call to come pick me up? LOL

 

[oilerlord]

The worst median mileage estimate we have seen was 152 miles. My family of four drove up to Freeport ME and back on December 31st, when it was about 9F, and we still got that range.

In September and October, we saw median ranges above 300 miles. 238 seems quite fair and sensible.

I absolutely understand the point that mwk, and others new to driving an EV are making, but some of us choose to treat it like the elephant in the room.

If a vehicle is rated at 40 MPG highway, and it varies by ~10% in real world conditions, I'd call that fair and sensible. You shouldn't have to "work" at achieving those numbers by pre-heating, pre-conditioning, driving 40 mph in a 65 zone, avoiding use of the heater, wearing battery heated socks, using a 12V electric blanket, drafting semis, etc. It should just (more or less) happen.

Because temperature causes range to fluctuate dramatically with EV's I'd like to see a summer/winter/combined EPA range rating instead of using one averaged number. That way, GM could (for example) advertise 300 miles of range along with 152 and 238 respectively. Stating a winter range number on the Monroney sticker may give buyers in northern climates pause, but it would at least set fair and sensible expectations for those driving an EV in winter's cold.

 

[mwk]

Here's another question I've just been mulling over, related to this issue of range. You say the meter itself is using some sort of algorithm that takes a "best guess" at the car's range, given recent driving history, length of trip, use of hvac, outside temps, etc.

So my question is this: Is a fully-charged battery the same no matter what? What I'm hearing is that the battery pack really hasn't actually "lost" 50% of its warm-weather capacity, but rather, given my driving habits I'm being ultra-inefficient so I'm drawing it down much more quickly. The "scoring" panel in the car would tend to agree, since I seem to get a -5.0 on all attributes other than my own driving (i.e. climate controls). So if I suddenly turn off the heat, drive the car at a steady 45 on a highway during the day with the headlights off, and when I leave the driveway in the morning the range meter says a maximum of 130 miles...what happens when I get close to that 130 mile mark? Does the range start to creep up as I am driving? Does it just show zero range but the low battery warnings, etc. aren't going off?

I was just curious about that.

 

[GetOffYourGas]

My family of four drove up to Freeport ME and back on December 31st, when it was about 9F, and we still got that range.

Thanks for the data point, Neil. This is exactly what I was talking about. My range meter suffers from short-trip syndrome too. I rarely drive more than 5-10 miles before shutting the car off. This means that the car cools down and requires the heater at full power to heat back up. My range meter often shows 100 miles or fewer lately in the expected range on a full charge. But I have no doubts that I could get on the highway and drive for at least 140 miles (sadly, the distance to the nearest CCS charger that matters to me).

Ha. OK then, I guess I can try this weekend and take that 100 mile round trip and see what happens. If I don't make it back, who here can I call to come pick me up? LOL

If you take the trip in one or two shots, you should be fine. Where you'll run into trouble is driving a couple of short trips on the far end of your journey, especially if you are running the heater.

Because temperature causes range to fluctuate dramatically with EV's I'd like to see a summer/winter/combined EPA range rating instead of using one averaged number. That way, GM could (for example) advertise 300 miles of range along with 152 and 238 respectively. Stating a winter range number on the Monroney sticker may give buyers in northern climates pause, but it would at least set fair and sensible expectations for those driving an EV in winter's cold.

For the record, I agree with this 100%. For ICEVs, we are used to a highway/city breakdown. For EVs, the winter/summer spread is far more important. It will take time for the standards to catch up with this new reality, but we really should rethink the Monroney sticker for EVs.

Here's another question I've just been mulling over, related to this issue of range. You say the meter itself is using some sort of algorithm that takes a "best guess" at the car's range, given recent driving history, length of trip, use of hvac, outside temps, etc.

So my question is this: Is a fully-charged battery the same no matter what? What I'm hearing is that the battery pack really hasn't actually "lost" 50% of its warm-weather capacity, but rather, given my driving habits I'm being ultra-inefficient so I'm drawing it down much more quickly. The "scoring" panel in the car would tend to agree, since I seem to get a -5.0 on all attributes other than my own driving (i.e. climate controls). So if I suddenly turn off the heat, drive the car at a steady 45 on a highway during the day with the headlights off, and when I leave the driveway in the morning the range meter says a maximum of 130 miles...what happens when I get close to that 130 mile mark? Does the range start to creep up as I am driving? Does it just show zero range but the low battery warnings, etc. aren't going off?

I was just curious about that.

Actually, no, it's not the same. A cold battery holds less energy than a warm one. I think ideal temperature is about 60-70F. So in winter, you get a double-hit to range. Your battery holds energy, yet it takes more energy to heat and drive (cold air is denser, causing more drag).

 

[oilerlord]

Actually, no, it's not the same. A cold battery holds less energy than a warm one. I think ideal temperature is about 60-70F. So in winter, you get a double-hit to range. Your battery holds energy, yet it takes more energy to heat and drive (cold air is denser, causing more drag).

I've also found that putting winter tires on my EV has a bigger effect on range than it does on my other vehicles. That caught me by surprise.

 

[GetOffYourGas]

I've also found that putting winter tires on my EV has a bigger effect on range than it does on my other vehicles. That caught me by surprise.

That's interesting. Are the winter tires LRR? On your other vehicles, are your summer tires LRR? Because I've read that the switch from LRR to normal tires can cost as much as 15% of your range.

 

[SeanNelson]

I absolutely understand the point that mwk, and others new to driving an EV are making, but some of us choose to treat it like the elephant in the room.

If a vehicle is rated at 40 MPG highway, and it varies by ~10% in real world conditions, I'd call that fair and sensible.

I'd like to point out that some of the people are describing range decreases caused by heater use for quite short trips. With those kinds of trips the efficiency of ICE vehicles is also very badly impacted, certainly by far more than 10%. My Prius C, one of the most efficient ICE vehicles you can buy, used almost twice as much fuel per 100 km for short winter trips as it did for summer excursions.

 

[NeilBlanchard]

I've also found that putting winter tires on my EV has a bigger effect on range than it does on my other vehicles. That caught me by surprise.

That's interesting. Are the winter tires LRR? On your other vehicles, are your summer tires LRR? Because I've read that the switch from LRR to normal tires can cost as much as 15% of your range.

Nokian Hakka R2's are very low rolling resistance, and so are Michelin X-Ices (whatever generation they are on).

 

[GetOffYourGas]

I've also found that putting winter tires on my EV has a bigger effect on range than it does on my other vehicles. That caught me by surprise.

That's interesting. Are the winter tires LRR? On your other vehicles, are your summer tires LRR? Because I've read that the switch from LRR to normal tires can cost as much as 15% of your range.

Nokian Hakka R2's are very low rolling resistance, and so are Michelin X-Ices (whatever generation they are on).

I'm not sure how that relates to the question. Are those the tires that OilerLord is using? Did I miss where he mentioned that?

 

[SparkE]

Re: "cold temp driving" : stumbled across this 12V electric blanket for cold weather driving. This might be ONE answer to not losing so much winter range in a BEV (don't use the heater as much) :

https://www.amazon.com/Electric-Blanket-Tailgating-Emergency-Stalwart-BLUE/dp/B001QJQ22O/

I am sure there are other brands.

 

[Evoforce]

Let me summarize: heat-pumps don't work worth a darn in weather colder than freezing, which afflicts most of the US.
That is why every heat-pump home furnace in the world also has a secondary heat source: a hot-wire electric heater component, to take over from the heat-pump when it's cold out.
So there is very little point in a heat-pump in a car. It would add mechanical components that add cost and wear out and break, and would only save a bit of energy for those in California-mild climate.
The only reason the Leaf has one is because they had a tiny battery, and needed to save every possible watt-hour to provide any interior heat at all.

Let me summarize: you are mistaken. Heat pumps are useful down to almost ten degrees below Freezing, and this means that they will be useful for about 90% of the year - 100% in many climates. GM chose to do without one to save themselves money, not because "there is very little point in a heat-pump in a car." It's kind of sad to see people rationalizing every mistake or cheap-out that GM commits. The Bolt is a very good little car. If they fix the seats, road noise, and wasteful heating system it will become a great little car.

And let me add... we need more quick charging infrastructure.

 

[SparkE]

What we *really* need are vehicles that support ultra-fast charging (at least 150 kW up to, say, 50% SoC).

IMO, The most important thing to make BEVs more palatable to more people (especially those with only 1 vehicle) is faster charging capability in the vehicle. When cars are widely available that can charge at 150 kW, BEVs will get rid of the true major holdback for people. That "but what if I want to drive to ..." is as much about (if not more-so) having to wait for 60 minutes to add 150 miles of range than it is by "lack of charging stations". It is possible today to drive from California's northern border to its southern border in a Bolt, as well as drive to Las Vegas and Reno. There are, today, CCS charging stations already sited (sites chosen) and approved and budgeted to make it even easier, and possible to easily drive into AZ. But there are currently NO vehicles that will charge at 150 kW (350 amps) using CCS. Heck, *I* take an ICE vehicle if I want to drive more than about 300 miles. It's not that I *can't* recharge - it's that I don't want to wait at the dam station for the electrons drip-dripping into the battery. If I could add 120 miles in 15 minutes (e.g., a 300 amp draw @ 400V) - then yeah, I *would* use my BEV to drive to L.A. or San Diego or Reno or Eugene, OR. It isn't lack of *stations* holding me back - it's lack of capability in the *vehicles*. By the time 150 kW-capable CCS vehicles are generally available, there will be a substantial network of charging stations installed and ready to charge them. In California, they are already planned. And that isn't counting the 2 OTHER networks (not funded by CEC) that are being put in place over the next 2-4 years : VW's "dieselgate" network, and Ionity (which are going in all over the country).

 

[oilerlord]

I'm not sure how that relates to the question. Are those the tires that OilerLord is using? Did I miss where he mentioned that?

I have a set of 225-50/R-17 Pirelli-Winter SOTTOZERO 3 tires on the Benz. They stop well in winter...but from experience, I think these may be HRR tires. I've had a dramatic reduction in range with these tires. I guess I might have been able to find skinnier tires that would fit, but I think it's best to follow the recommended sizes on the door label. (Our) Costco wouldn't install any size outside of what the manufacturer recommends for the car.

 

[winterescape]

Thank you, Oilerlord. I'm going to be posting here less, now that I'm sure I'll be leasing a 2018 Leaf rather than a 2017 Bolt, but it's hard to resist talking about things that are applicable to all EVs. Like this:

I have the same setup at home and i'm convinced that most people that are desiring a heat pump in the Bolt don't have one at home or have never used one. Heat pumps heat slowly and if it was cold outside, 32 or below, the air coming out of your vents would not be very warm and cozy like you want on a cold day. Especially if it was outside and the heat pump had to warm all the vents up slowly. When my heat pump at home kicks on when below 32, it takes a long time to just get the ducting warm and you never get "hot" air out of the vents. It raises the temp of the input air by 10-12 degrees at most when in the lower digits, if that temp outside is in the teens, less. I have mine set to switch over to gas at 38 due to price of natural gas here, it's just not efficient to heat with heat pump below that. The other thing would be defrost, heat pump won't pull moisture out of the air so i think when the defrost is on, you'd need element heating and then A/C which defeats a lot of the purpose of using heat pump. That being said i love my heat pump at home for mild weather but I honestly don't see the cost/benefit of it in a car. That is a lot of complexity there to break when if you truly think about it, how much efficiency would you really gain when considering everything? (window defrost, heat pump defrost mode in <32, cold weather, how much you use the heat in mild weather).

EV heat pumps are ALWAYS, as I have written before, combined with PTC (resistance) heaters in EVs as well. The two work together, varying their contributions according to what is best for a given situation. You say that I haven't taken into account diminished heatpump efficiency below 32F. In fact I have, but I'll make it more clear. Leaf drivers have found that the particular setup we have in our heatpump-equipped Leafs stops giving a range advantage over PTC-only Leafs at about 14F. It's not a matter of the heatpump starting to use more energy than the PTC - that never happens. Instead, the PTC contributes more and more heat to the system, until at about 14F it is providing the lion's share of heat. The heatpump shuts off at about 7F, IIRC, but by then you don't notice any extra range from it.
Here are my observations about Leaf heatpump usefulness:

* 45F and above: the car loses no more range to heater use than it does in hot weather to A/C use, generally two or three miles less on the Guess O Meter. This is vastly better than using just PTC heat!

* 45F - ~39F: roughly 5 miles of range lost, even though the GOM doesn't usually reflect this. Still much better than PTC only.

* 39F - ~30F: roughly 7 miles of actual range loss. Still only about 2/3 as much power used, compared to PTC.

* 30F - 24F: roughly 10 mile range loss. AT this point you know that you're losing lots of range to heat, but it is still less than PTC-only Leafs.

* 24F - 14F: roughly 15 mile range loss. A small advantage remains, but it is just a few miles of range.

*14F and lower: indistinguishable from PTC-only heat. Roughly 20 miles of range (about 33%) lost compared with no heat. This is from a total range of maybe 65 miles, real world.

A very interesting paper on optimal cabin heating for an EV that evaluates the design trades...

https://www.sae.org/news/2018/05/new-bev-thermal-optimization-studies