winterescape
Posts: 158
Joined: Sun Jun 25, 2017 1:35 pm
Location: Upstate, NY

Bolt winter performance, an ICE comparison

Tue Dec 19, 2017 10:28 pm

We have both a Bolt and a two year old ICE vehicle and we, for some reason, live in upstate NY. I have tracked MPG of the various vehicles we have owned, all posted on fueleconomy.gov

I thought I might do a quick comparison of the fuel economy hit in the winter between our current ICE to our Bolt.
ICE = EPA rated at 26MPG, Vehicle has 40K miles and is 2 years old. Vehicle lifetime average is shown at 26.5MPG
I selected a few frigid times where I had concurrent fuel up data for the ICE
1/14/16 = 21.3 (cold & remote start used)
1/22/16 = 19.7 (bitter cold and remote start used)
3/7/2016 = 21.6
12/20/16 = 21.6
12/14/17 = 22.8 (cold but no remote start)

Avg = 21.4 / 26.5 = 19% drop from average in cold weather

Bolt EPA 238Miles, observed low point 172 miles when full, vehicle plugged into a level 2 charger in a hotel parking lot overnight, temps dropped into the 20’s but warmed to freezing by departure time, similar data point with Bolt in garage (34 deg) and outside temps in the teens for the last several drive cycles. Cabin temp set to 72, like to use the "precondition" feature before driving, seat heaters on "auto" frequent use of heated steering wheel (what a great feature)

172/238 = 28% drop from average in cold weather


Observations:
1) The Bolt DTE “distance to empty” being prominently displayed makes the driver keenly aware of the reduced distance in the winter, contrast this to the ICE where just the gas level is displayed, so the driver has no idea that the distance to empty has dropped off by 20%. No one monitors the DTE screen on an ICE vehicle, no one.

2) With the lack of significant waste heat, the battery characteristics, and resistive cabin heating, the Bolt DTE falls off by a larger % than an ICE vehicle in the cold weather, but not by an unreasonable amount.

Conclusion: Stay warm this winter, enjoy your Bolt, and think Spring!

LeftieBiker
Posts: 793
Joined: Tue Jan 10, 2017 7:13 am

Re: Bolt winter performance, an ICE comparison

Tue Dec 19, 2017 11:43 pm

At some point GM is going to have to offer a heat pump, if not on the Bolt then on their upcoming E-SUV. As more 200+ mile electric vehicles enter the market, Winter range will become a bigger selling point.
2018 Nissan Leaf SL with Pro Pilot

2009 Vectrix VX-1 with 18 Leaf modules.

BarfOMatic
Posts: 59
Joined: Sat Feb 25, 2017 8:03 am
Location: Santa Clara, CA

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 2:04 am

LeftieBiker wrote:At some point GM is going to have to offer a heat pump, if not on the Bolt then on their upcoming E-SUV. As more 200+ mile electric vehicles enter the market, Winter range will become a bigger selling point.


The colder it gets outside, the less effective a heat pump is. In heat mode, it is basically being an air conditioner in reverse, extracting what heat it can from the outside air and transferring it to the indoors. The less heat available outside, the cooler the air coming out the vents inside. Heat pumps do best when it is above freezing and when the difference between the temperature outside and what the thermostat is set at is 10-15 degrees. So while a heat pump would be *great* from *my* point of view (in my part of the west coast, winter daytime temps are generally between 45-65), in upper NY State, having just a heat pump wouldn't be anywhere near sufficient.

Offering an option of an additional heat pump (in addition to the resistive heater) for $1500-$2000 would be a good thing, IMO.

LeftieBiker
Posts: 793
Joined: Tue Jan 10, 2017 7:13 am

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 9:09 am

That was pedantic, as no manufacturer offers ONLY a heat pump. They are always in combination with a PTC heater. I have actual experience with a heatpump-equipped system in Upstate NY, and it really helps the range down to about 25F, and makes some difference down to about 15F. That means that for roughly 90% of the year it increases my Leaf's range significantly. The problem with PTC heaters is that they suck power in large amounts regardless of the weather. So when you turn on the heat to defog the windshield on a chilly but not cold morning, you are sapping the vehicle's range much more than would a "hybrid" heatpump-PTC system. What I wrote stands.
2018 Nissan Leaf SL with Pro Pilot

2009 Vectrix VX-1 with 18 Leaf modules.

GetOffYourGas
Posts: 1158
Joined: Tue Oct 20, 2015 5:25 pm
Location: Syracuse, NY

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 11:25 am

When I had a 24kWh Leaf, I longed for a heat pump. Now I have a 60kWh Bolt and I could hardly care less. Yes, it uses more energy but so what? I'm rarely driving that deep into my battery. It just means it takes slightly longer to recharge (which happens while I'm working anyway).

There was an article written a few years back which showed that an EV's relative fuel saving increased during the winter. It is counter-intuitive, but the math works out. Basically, the fuel usage goes up by a larger percentage, but since it started out as a smaller number, it goes up by a smaller absolute cost. I wish I could find the article, but I don't even remember which site I read it on.

Unrelated to heat/range in the cold, there is a solid benefit to an EV - they don't lose driving performance in the cold. An ICE needs to warm up its engine before you demand anywhere near full power. An EV is ready to go, especially the Bolt with its thermally managed battery. I was able to get 145kW out of a cold-soaked Bolt (single-digit F) right from the get go. Couldn't do that in an ICE.
~Brian

EV Fleet:
2011 Torqeedo Travel 1003 electric outboard on a 22' sailboat
2012 Leaf SV (traded for Bolt)
2015 C-Max Energi (302A package)
2017 Bolt Premier

LeftieBiker
Posts: 793
Joined: Tue Jan 10, 2017 7:13 am

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 11:36 am

Yes, it uses more energy but so what? I'm rarely driving that deep into my battery. It just means it takes slightly longer to recharge (which happens while I'm working anyway).


I assume that you know that individual range needs vary, but this is why I wrote that GM will need to offer a heatpump equipped heater in their upcoming SUV: the Bolt has range to spare for most needs. The E-SUV will, especially if it uses the Bolt powertrain, have less range to begin with than the Bolt, and so the Winter range drop will bring it lower towards 100 miles - especially if it has a transmission-based AWD system. Why not just have four wheel-motors? For one thing, that isn't what the Bolt uses, and GM will be looking for economies of both scale and simplicity.
Last edited by LeftieBiker on Wed Dec 20, 2017 8:00 pm, edited 2 times in total.
2018 Nissan Leaf SL with Pro Pilot

2009 Vectrix VX-1 with 18 Leaf modules.

GetOffYourGas
Posts: 1158
Joined: Tue Oct 20, 2015 5:25 pm
Location: Syracuse, NY

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 12:25 pm

Yes of course everyone's needs vary. You, for one, are surviving with a Leaf. A Bolt has far more winter range than a 2017 Leaf, even though the Bolt doesn't have a heat pump. 2018 Leafs are a different story, but we know you don't have one of those (yet, anyway). GM may or may not eventually go with a heat pump. Harping on them for excluding it from the Bolt feels kind of silly.

Regarding a future BEV SUV, I really doubt that they would go with a transmission-based AWD. Tesla has shown that using two motors with different gearing can improve efficiency. Traditionally, AWD systems decrease efficiency. I also doubt they would put the same battery in a larger car. I'm betting they scale up the battery as needed to maintain a decent driving range. Time will tell which of us is right.
~Brian

EV Fleet:
2011 Torqeedo Travel 1003 electric outboard on a 22' sailboat
2012 Leaf SV (traded for Bolt)
2015 C-Max Energi (302A package)
2017 Bolt Premier

EldRick
Posts: 363
Joined: Thu Dec 22, 2016 8:36 pm

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 6:00 pm

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 gas or 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.
Last edited by EldRick on Thu Dec 21, 2017 6:37 pm, edited 1 time in total.

winterescape
Posts: 158
Joined: Sun Jun 25, 2017 1:35 pm
Location: Upstate, NY

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 6:26 pm

EldRick wrote: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.


Cost/ complexity/ reliability/ time to market VS potential benefit

As I posted in another thread where this came up, someone pointed out that BMW, KIa, and Nissan all had a heatpump. I hypothesized that GM invested in a bigger battery over the heatpump. Even though I live in upstate NY, I think that was likely a good trade.

I will however add that I am warming ;) to the idea of a "EV cold weather package" option. This might include a heatpump and a more aggressive battery warming algo, among other optimizations for those of us that experience fewer extreme high temps and more extreme cold temps. As highlighted above, I would need GM to quantify the potential benefit to me in investing extra for that package.

LeftieBiker
Posts: 793
Joined: Tue Jan 10, 2017 7:13 am

Re: Bolt winter performance, an ICE comparison

Wed Dec 20, 2017 8:06 pm

EldRick wrote: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.
2018 Nissan Leaf SL with Pro Pilot

2009 Vectrix VX-1 with 18 Leaf modules.

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