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Had some very weird behavior from my bolt today. Typically have always been around 250-270 estimated range except since it's colder have been sitting closer to 4 kw/mile now. We've have a cold snap in WA and today I took my car up into Snoqualmie Pass from Issaquah which is a pretty consistent climb and total of maybe 30-32 miles door-to-door. Anyways, we left with a solid half a battery, arrived at the pass a little concerned and with around an 1/8 and 30 miles estimated. (All of the return trip was downhill so not totally unexpected but still should have been more than ok.). So, we set out, defrost on but 62 degrees selected on temp but no heat/ac selected (no auto selected either). For the first 15 miles of the return trip the bulk of which was downhill we increased estimated range the entire way, went up one minor stretch of hill area for a few minutes and the range collapsed to a warning and continued to get worse from there, down to limp mode and a flashing capacity bar. Luckily we were able to pull off and plug into a chargepoint right by my work so we could walk with our baby to our Outback that we had luckily parked at our business. We live on a mountain so now way was the car getting back home. I have done this exact same trip, in the rain (it was raining and snowing tonight) being way more brutal on efficiency with the heat running in the last few weeks and have always gotten all the way home with at least a 1/4 battery left. This was absurd, we used around 30 kwh to go 60 miles. With my old Volt and the new Bolt I have never really averaged under 3.7-4.0 mi/kwh except when it was in the negative temps. On this trip I actually watched our overall average (I only have ~2,000 on it) drop by 0.3 mi/kwh from this trip alone.

So here is what I noticed on the trip and what settings I had:

1. Thermostat set at 72, defrost and feet. No auto and like in the past I would let the heater core warm up, toggle off the heat/ac and let the heater core blow out the heat until cool. (We were literally eating the battery on the way up so was already getting worried.) Fan set around 2-4.
2. More than a few times on the trip when I shut off the heat/ac and left the fan running but adjusted the thermostat up the car would blow way hotter air. Are there certain conditions the car overrrides the heat setting or is mine just stuck to high?--Based on the normal kwh usage it has not been stuck and when heat/ac was off in the past it would sit at 1kwh usage.
3. The car on the way home felt like we were dragging a cow. Even my pedestrian (wife) asked if we were in L due to the amount of drag and when we were going down the pass the car should have been gaining speed not crawling to a slow going down a mountain in D. Unless it got stuck this morning, I have never found a hotter or hot brake rotor in the past with my IR gun. Possible it just happened this morning or something I guess but the car did not feel like it had a stuck rotor this morning coming down our mountain. Tires may be a smidge low right now (I filled them up a few weeks ago in the 40 degree range at night and now we are in the 30s) but not enough to feel like this.
4. Car went from 3 battery notches to one and then flashing in a very short amount of time even after I had taken steps to completely decrease any and all heat usage, cracked windows (sucked total A** driving like that in 35 degrees, as an FYI) and was massively hypermiling (uphill stretches were always at least 2 mi/kwh and downhill stretches were true or as true as I could coasts.
5. To make things worse my fan speed up arrow is stuck in as of tonight so I was not able to increase speed past 1 on the way home. Made the foggy window issue I always have (pretty much always have to drive with the defrost going in our rain/climate) a serious safety issue.--Not really related to the battery issue but really Pi**ed me off tonight.--That will be fixed soon along with my rattling mirror assembly.
6. On the way up, when I saw the weird battery usage I started hypermiling and continued true hyper-miling all the way home going downhill. We should have had way more than enough battery power to get home.
7. I did notice that at multiple points when we stopped by the destination the battery usage was fluctuating between 2-9, then back down to 1 kwh (which is where it usually rests when I am at a stop, who knows how accurate it is but my volt was always at 0.5 or effectively less when stationary, this normal?) even though the heat/ac was off and no heat was blowing just cool air. It would peak out for 10-15 seconds then drop back down for the same amount of time then peak back up.

I'm at a loss to explain the odd kwh usage with the heat and the fact that even when the heat/ac was selected off it was still cranking out heat being set at 72-74. I will say that I have noticed in this car if I set the thermostat temp to a low temp like 70 when it is cold outside and then quickly set it to 80+ it will instantly crank out super-hot air which has made me expect all along that when in heat/ac mode the car heats up the heater core to some stupid high temperature and then controls air temp by blending or something. I am probably super-wrong on how this works but either way then my car is apparently doing something stupid and wasteful with the heater core. With the car at a stop and heating to 70-74 (ish) I have noticed the typical draw is 7+ kwh for reference. That is when it is in the 40s outside. That does not in any way fit how things worked with my volt that had eco/comfort and would draw significantly less to the heater core based on the desired/set temp.

Can anyone elaborate how the temperature demand system works on the bolt? Does it change power to the resistive heating element based on the desired temp? If so, it seems something had gone awry with mine since the heater core (when heating) always seems instantly ready to blow scorching hot air at the turn of the temperature dial?

I know this is a novel and I generally love this car but this was disconcerting. I have never had any form of range-anxiety even with 200+ mile trips (always got home with more than a 1/4 battery remaining) but this was really bad.

If anything is positive from this, I found out that this specific chargepoint is significantly cheaper to charge per kwh than home charging. $0.50/kwh for ~6.6kwh (maybe a little less for efficiency losses) but that would still run me over $0.75 and this is literally less than a block from my work and is in a lot that I think will not fill up often. At least something good to come out of this close call. I can say with certainty that I sure as **** won't be driving with my baby in this car for anything but short 100 mile or less trips until i can find the cause of today's range decrease. Although I did not have a chargepoint app or card, I think I may be getting one soon just in case we have a close call again. Getting this car and having previously had the volt was precisely the reason why I thought I would probably never need to charge somewhere like this. It just sucks I need to get there in 10 hours so that I don't stop charging and keep getting billed.
 

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Cold weather reduces range and uphill kills it. Running the heater can use up battery power quickly too.
Sounds like the cold weather has caused your issue. You said 35°. The triple combo is a heavy toll on range.

Be prepared for drastic range loss in COLD weather. It's advisable to keep the battery charged
during winter/cold weather driving. Never underestimate range loss due to conditions.
 

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Discussion Starter #3
As a past owner of a Volt (with an absolutely stupid HVAC system that constantly was crapping out on me blowing cool air and still burning a ton of KWH), I'm quite aware of all of the normal decreases to expect between HVAC and battery conditioning.--Heck I scrutinized for two winters before I finally had my car spend a few months in the shop as they finally figured out a venting/duct piece that blended air was broken (their words).

If when using the HVAC conservatively or in this case NOT AT ALL (for most of the trip) and merely driving in 35 degree weather torches a half a battery in 60 miles, Chevrolet has taken a massive step backwards here compared to the Volt in winter. I can't imagine conditioning the pack takes this much drain in an hour of driving.

Yes it was uphill, but I spend pretty much the entire last 30 miles coasting back downhill and was hypermiling the entire way back and a good chunk of the way up. And like I said before, there have been more than a few times in the last few weeks where I have made this trip in the 40s driving aggressively with HVAC on modest levels and have had zero range issues. 2 mi/KWH does not in any way fit with the previous performance characteristics of the vehicle and a 5-10 degree drop in temperature doesn't explain an almost 2-fold drop from my most recent cooler weather stats.

The dragging of the car and performance decreases don't quite fit with the cooler temps though...
 

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As a future Bolt EV owner, but one that has used a Tesla Model S in the past...
I feel new technology is new technology. No matter how optimistic I want to be about an electric vehicle I will follow these rules for peace of mind and not to have battery anxiety:
1) Always leave the car plugged every night independently of how far I am going (charging up to 80% and for long trips an eventual 100%).
2) Try my best to park in heated garages during the winter (I am blessed my work offers that), so no worries 90% if the time.
3) Do my best to understand the relationship between AC/car technology and their influence on the battery according to different temperatures, types of tyres,
road conditions etc...
And above all, thank all of you for your infinite input in this forum which is teaching me so much. And I expect to learn and prepare myself even more for months to come until my car arrives...
 

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Discussion Starter #6
see if it repeats, or see if it repeats on a flat road in similar temps. if it does, take it to the shop.
Agreed, I'm watching it like a hawk for the next few weeks. Going to check the tires tonight just to make sure but the overall range decrease just isn't what I would have expected compared to what I had grown accustomed to with the Volt in these types of temps with no HVAC going.
 

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Beware headwinds - cold is very damaging to range - combine that with head winds and you can lose 40% no problem if you don’t change your speed
 

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Agreed, I'm watching it like a hawk for the next few weeks. Going to check the tires tonight just to make sure but the overall range decrease just isn't what I would have expected compared to what I had grown accustomed to with the Volt in these types of temps with no HVAC going.
Don't rely in the Volt to compare the Bolt :nerd: It's NOT the same >:)
 

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Car went from 3 battery notches to one and then flashing in a very short amount of time even after I had taken steps to completely decrease any and all heat usage...
Have you been using Hilltop Reserve mode exclusively? There's been some speculation that if you don't fully charge the battery from time to time the range indicator and capacity indicators may not properly recalibrate. Because of this it's my plan to fully charge the battery every few weeks even though I will normally use Hilltop Reserve mode.
 

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the dragging along with rapid loss of range seems to be indicative of something that might have frozen in the conditions. Like ice buildup on the brakes or parking brake. Then later it thaws and all seems to be back to normal.
 

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Agreed, I'm watching it like a hawk for the next few weeks. Going to check the tires tonight just to make sure but the overall range decrease just isn't what I would have expected compared to what I had grown accustomed to with the Volt in these types of temps with no HVAC going.
Hi - also noticed with recent seasonal weather in Metro Boston (30s instead of >60 F) my mileage decreased (about 30%, 4 -> 2.8 miles per kW) and it took longer to charge overnight. Will take advantage of preconditioning while plugged into 240V at home ... but think this is what Law of Chemistry and Physics would predict. This winter we should have enough Bolts around the country to get an idea of what the seasonal weather related changes lead to. Must confess to being very lead-footed (typical) MetroBoston driver and a more reasonable driver might have noticed less impact. But then I drive fast.

Thank you for your post, valuable data and vivid circumstances. I for one will not undertake trips this winter with my Perfect Wife or Prince of a Son without making sure we have sufficient battery reserve and/or fast recharging identified. Your story really reinforced this for me. Since it does get somewhat Seasonal here will see if range decreases to 50% when it gets really cold.

p.s. Am sure you have thought long of it but it sounds like your environmental settings were high enough it would have affected mileage. Am finding that with seat and steering wheel heating on, I can run the general heater at lowest setting (or off) and do ok.
 

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Discussion Starter #12
Hi - also noticed with recent seasonal weather in Metro Boston (30s instead of >60 F) my mileage decreased (about 30%, 4 -> 2.8 miles per kW) and it took longer to charge overnight. Will take advantage of preconditioning while plugged into 240V at home ... but think this is what Law of Chemistry and Physics would predict. This winter we should have enough Bolts around the country to get an idea of what the seasonal weather related changes lead to. Must confess to being very lead-footed (typical) MetroBoston driver and a more reasonable driver might have noticed less impact. But then I drive fast.

Thank you for your post, valuable data and vivid circumstances. I for one will not undertake trips this winter with my Perfect Wife or Prince of a Son without making sure we have sufficient battery reserve and/or fast recharging identified. Your story really reinforced this for me. Since it does get somewhat Seasonal here will see if range decreases to 50% when it gets really cold.

p.s. Am sure you have thought long of it but it sounds like your environmental settings were high enough it would have affected mileage. Am finding that with seat and steering wheel heating on, I can run the general heater at lowest setting (or off) and do ok.
By myself, yes, I would get away with a lot less for the general heater although in our VERY moist climate (without cracking a window) the windows fog in minutes pretty much always. Since I had the wife and son with though, yeah, he needs to stay warm. If he was older than 11 months, i would do like my best friend does in WI and give them a blanket. See my next post as I think i have found most of what the range loss conditions were.
 

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So an update...

I did find that the tires were all at ~27 PSI (it took a few minutes tonight to figure out how and why the tires could be that low after last having topped them off in the 40 degree range. I forgot that in between my last tire top-off that I did when it was cool, I had the tires rotated. I'm guessing they "guessed" at the tire specs or something or the car was in the shop and the tires topped off when warm? Between that and the resistance from slush would probably explain the drag feeling. Tonight I road home with filled tires in the rain going up our mountain and things were better as one would expect. I won't have a true acid test until I descend tomorrow morning since that's usually crazy predictable.

Also, I forgot about the auto defrost setting that was common with my Volt. Since I had the temp set high (didn't care since the Heat/AC were off so really wasn't paying attention to it) but blowing the fan (keep in mind the button was stuck at level one for the fan speed and still is as of tonight) to keep the windshield clear, apparently, when it is cold the car overrides your heat/AC setting and can sporadically run the heat at full bore (which explains my high KWH usage when stopped at the destination even though the heat was off but the fan was blowing). I'm guessing this is to prevent the compressor or something else from freezing your car or you to death with cooled air. I disabled the auto defrost (as I did in my gen 1 Volt) and found the heavy KWH usage to be gone. This would perfectly explain why I was not getting much/any heat (blowing at 1 and only on the windshield setting) but the battery was plummeting all the way up and down the pass. I am not sure if the usage would have been so severe if a different temperature had been selected or not... Might be something to test at a later date. Regardless, on the way home when we almost ran out, the temp was set to 62 so whatever heat was being applied to the heater core was being decided by the car and probably not my thermostat settings.

Overall, there is probably a lesson that even small oversights or happenstance can quickly change your circumstances. Having even our L1 charger with might have saved us some anxiety as we could have charged for 5-6 hours at the destination and had significantly more cushion. Didn't think I need that cushion...
 

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Discussion Starter #14
Don't rely in the Volt to compare the Bolt :nerd: It's NOT the same >:)
Agreed, but I would expect comparable performance and just maybe slightly worse due to worse aero and maybe more power needed to keep the larger pack above a certain temp if not pre-conditioned (but that's totally a guess).--High expectations for the lessons they would have learned from the the Volt though....

BTW, check the last post though since I think the two main causes have become apparent, one in my control and one sort of not. I think having driven the Volt through 3 different states and 3 very different winters/climates, you get a good idea of how to make concessions in climate control and driving style to make it through the winter without crippling your range. Especially since here it is rarely under freezing and aside from condensation, most days I can omit climate control altogether as long as the baby doesn't become a human popsicle in back. Or possibly worse yet, the wife.
 

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Some of the technical documentation said that the bottom cooling plate of the Bolt was sufficient for radiative cooling - so the battery cooling loop isn't connected to the radiator. This would imply that perhaps in cold weather the heating coils would need to be used more to keep the battery warm since the plate would radiate battery loop heat, especially (obviously) if you store the car in a cold garage or outside. What I tend to do is keep an eye on my usage when at a stop light, anything above 1kW indicates battery conditioning (which should indicate on your usage calculator too)
 

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What I read didn't say the cooling plate was sufficient. It said the coolant circuit was sufficient. I assumed they included the thermal losses from the antifreeze being pumped through the hoses to the reservoir, and back to the pack. If that is the case, simply shutting off the circulation pump would reduce heat loss, in cool conditions.
 

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Some of the technical documentation said that the bottom cooling plate of the Bolt was sufficient for radiative cooling - so the battery cooling loop isn't connected to the radiator. This would imply that perhaps in cold weather the heating coils would need to be used more to keep the battery warm since the plate would radiate battery loop heat, especially (obviously) if you store the car in a cold garage or outside. What I tend to do is keep an eye on my usage when at a stop light, anything above 1kW indicates battery conditioning (which should indicate on your usage calculator too)
What kind of numbers have you been seeing a given temp. mind me asking.... With my Volt it was 2-3 for very short periods of time in the 32-34 degrees range. Have yet to catch it doing it with the Bolt. (Haven't really looked to be honest).
 

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If I read your OP correctly, it sounds like you started with a cold car/battery that was at ~50% SOC. I'm guessing that a significant amount of energy was used to bring the battery and cooling/heating circuit up to temperature. Since the battery is many times larger than the Volt, the amount of energy required to bring the battery up to temperature would be significantly more than you're used to (based simply on the amount of mass/volume). I know with my Volt, that my Level 2 charger cannot keep up with the energy used, simply for pre-heating the car in an enclosed garage. I'm also assuming that the car will heat/cool the battery as needed, regardless of the interior temperature setting. So, if the battery is being heated, you may experience heat from the blower vents (could be wrong). I know for the Volt, that in the summer when the battery is being cooled, I get cold air from the vent even with the AC turned off. This is because the compressor is still running occasionally to cool the battery.

Interesting read though. I too am coming from a Volt to a Bolt. I anticipate a bit of a learning curve and though we've got pretty cold winters here in MI, at least much of the terrain around the Detroit metro area is flat. :)
 

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JeremyK,

"So, if the battery is being heated, you may experience heat from the blower vents (could be wrong)."

The battery heater, and the cabin heater are on two completely different coolant loops. Ther battery pack has a resistance heating element, in its coolant loop, located at the front of the battery pack. The cabin heater has a resistance heating element, in its coolant loop, in a box under the hood. The heated antifreeze is pumped to a standard heater core located under the dash.

I played around with the heat, AC, and defrost steup the other day, when the temperature in the garage was 42F. I placed the thermistor probe from my VOM into the chest level center air louvers. Using the normal defrost button does not turn on the cabin heating element. Turning on the Max defrost button does. I saw the kW reading jump from .05-1.0 kW to 7 kW. Turning the temp control knob all the way up will turn on the heating element as you would expect. Within a minute, it will push to 100F air blowing in the duct. I waited several minutes, and did not see the air temperature, or the kW reading drop. Turning the temp knob down to 72F, the heating element shut off, as you could see by the kW reading. The heater core, being filled with antifreeze, holds quite a bit of heat. The air temp slowly dropped over several minutes. Eventually, the heating element came on again, as you would expect. Turning the temperature knob toward cool eventually causes a flap to shift in the ducting. You can hear the thunk, and a subtle change in the sound of the air flow. The air is now blowing past the AC evaporator core. It acts just like the heater core...getting very cold when the AC is on, and staying cool for some minutes, after the AC compressor has turned off.

The frustrating thing about this system is that the AC, and heater are not separately controlled. And other than a small thunk, and lacking a temperature probe, you don't know when it is switching from heating to cooling, and back. You could easily be twiddling around on the temperature control knob, trying to get the cabin temperature where you want it, and be going back and forth between AC, and resistance heat. NOT a good use of energy in an electric car. It would be very useful, if they put them on separate knobs, or at least had indicator LEDs to show which system is operating.
 
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