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Discussion Starter #1 (Edited)
Summary

  • New Volts have a low battery range estimate that will increase over time based on the points below.
  • Volts in cold weather will see a drop in the battery range based on the points below. This will reverse when the weather warms again.
  • Volts with battery service will see the battery range reset to the lower factory default. Just like a new Volt owner, you will see this change as you drive the car normally over the next several days.
  • Volts with multiple drivers may see a drop in the battery range based on the points below. As a passenger, you can quickly determine why your partner is getting fewer battery miles than you (or vice versa!).
New Volt owners; or those who have had some battery service done; or those driving for the first time in fall/winter months can become anxious when seeing their Volt's battery range display a mileage estimate lower than the advertised EPA number they were expecting or were previously experiencing.

Some fear the lower battery range estimate indicates a battery problem of some sort. Do not panic. It is much more likely the decreased battery range (actual or estimated) is due to a change in driving style, or in environmental conditions, or the car's conditions, or all the above.

Four Main Points About Volt Battery Range

1. The battery range display is an estimate based on the past, it's not an absolute.

The Volt attempts to predict how many miles you will be able to drive on the full battery based on your past few days of driving. A brand new Volt typically has no real past driving results to base an estimate on, so it displays a range estimate of 36-38 miles. This can vary a bit based on pre-delivery driving by the dealer.

The actual miles you get from the battery can be higher or lower than the displayed estimate based on factors discussed below. In general, all things being equal, if you drive consistently every day, the Volt's battery miles estimate will come very close to the actual miles you will get. Again, this assumes little or no change in your driving style or environmental conditions.

2. Your driving style affects the battery range (actual and estimated).


The way you drive greatly affects how many miles you will get from the battery. If you change the way you drive for a few days or so, it will be reflected in the Volt's estimated battery miles as well.

  • Speed. Slower speeds will deliver more battery miles. The faster you drive the more energy it takes to push through air resistance. The battery will deliver more driving miles at a steady 30 MPH than it will at a steady 70 MPH. Generally, you'll drive further at speeds under 50 MPH than you will at speeds over 50 MPH.
  • Cruise Control. The Volt has a great cruise control. Using cruise control will often be more efficient (deliver more battery miles), than not using cruise control because many people have a hard time keeping a very consistent speed. For the Volt's cruise control, this is easy.
  • Anticipating Change: Starts and Stops. Starts and stops that keep the green ball centered in the dash will enable more miles to be driven on the battery than rapid starts and stops which will waste more energy. Anticipate stops and slow down gradually rather than "speeding to a stop". Try to maintain inertia, as a rolling start will require less energy than accelerating from a dead stop.
  • Drive vs. Low Regen. Drive creates the same amount of regen (electricity regeneration) that Low does when slowing down, but Drive takes a longer distance to do so. With Drive, you can coast, with Low you can slow the Volt down quicker without using the brakes and thus recover more battery range in a shorter distance than Drive. Some people drive in Low all the time. Some downshift into Low only when approaching slowed traffic. Some feel unsafe using Low without tapping their brakes. Whatever your choice, Low pumps more electricity back into the battery than Drive given a short stopping distance.
  • Climate Control. Not using the heater, the A/C, the defroster will be more efficient (deliver more battery miles), than using them. Eco uses more electricity than not using climate control. Comfort uses up more battery miles than Eco. Of course, if you need them, use them. Just be aware that your battery miles (and estimated range) will be reduced. At speeds less than 50 MPH, popping open the window a half inch will often clear windshield fog as well as the defroster.
  • Seat Heaters. If you need heat, the seat heaters use much less energy than using the the climate control heat. Try using the seat heaters instead of the climate control if possible.
3. Environmental conditions that affect battery range (actual and estimated).

The conditions you drive under can dramatically affect how many miles you will get from the battery. If these conditions change for a few days or so, it will be reflected in the Volt's estimated battery miles.
  • Rain/Snow. Pushing the car through water or snow on the road takes more energy (battery miles) than driving on a dry road. Higher tire rolling resistance and lower tire traction take their toll. Also, water is a more effective coolant than air, so the tires and lubricants operate at cooler (less efficient) temperatures. Plus, the wipers and defrosters are typically needed, drawing even more electricity. Wet or snowy conditions can therefore decrease miles (by up to 14% according to some Prius owners). Nothing you can do about rain or snow, just be aware you will get fewer battery miles on those days.
  • Road Surface. Concrete is the most efficient driving surface, asphalt second, chip and seal is worst. Road roughness can increase rolling resistance up to 20% due to energy dissipation in the tires and suspension (10% loss of mpg).
  • Wind. A strong headwind can reduce battery miles by increasing air resistance. Strong winds often accompany rain and snow storms.
  • Outside Temperature. Colder outside temperatures reduce driving range for a number of reasons including the fact that thicker lubricants have more resistance requiring more battery energy to overcome. Colder weather often results in increased use of the climate system, further reducing miles. Nothing you can do about outside temperature, just be aware you will get fewer battery miles on colder days than warmer days.

    The chart below from an actual Volt owner show the affect that temperature alone has on battery range (next to it is a chart showing the amount of energy used to travel 100 miles vs. outside temps). The lower the seasonal temperature, the more energy it takes to travel, resulting in fewer miles on a full charge:
    Outside Temperature vs. Battery Range.jpg Outside Temperature vs. kWh Used.jpg
    http://gm-volt.com/forum/showthread.php?151273-3-Years-of-OnStar-Data-Comparing-Effect-of-Temperature-on-EV-Range
4. Volt conditions that affect battery range (actual and estimated).

The condition of your Volt can dramatically affect how many miles you will get from the battery. If these conditions change for a few days or so, it will be reflected in the Volt's estimated battery miles.
  • Tire Pressure. Maintain the correct tire pressure. Low tire pressure can reduce you battery miles by up to 10%. Correct tire pressure is more efficient, maximizes battery miles. Low tire pressure creates more rolling resistance and therefore consumes more battery miles. Check tires weekly, or at least once per month. Some even keep their tires inflated to a slightly higher 40 psi.
  • Winter Tires and Wheels. These tires, plus their often heavier wheels, can increase rolling resistance and therefore decrease battery miles.
  • Preconditioning. The 240v EVSE charge stations have the advantage of allowing you to pre-start the Volt and warm (or cool) the cabin at max comfort temperatures for 10 minutes using (mostly) the house electricity rather than the battery. If you do this 15 minutes or so before departure, your car will have 5 minutes to replenish if needed and you won't need to draw down the battery range as much during your drive. The 120v EVSE does not supply enough power to precondition the Volt this way, and more battery power is robbed to make up the difference. A refinement is to delay charging so it completes about 15 minutes or so before you plan to leave. The battery will be a bit warmer than if it had finished charging hours earlier.
  • Clean & Waxed Car. MythBusters showed that a dirty car can decrease fuel efficiency (battery miles) by up to 10%. A clean Volt has less air resistance than a dirty Volt. It looks better too. Wash your car weekly, or at least every few weeks. Package delivery services and airlines know this and keep their equipment clean. http://dsc.discovery.com/tv-shows/my...-clean-car.htm

TIP: Keep Your Volt Plugged In

Yes, you should always keep your Volt plugged in if possible. It will not hurt the car. Instead, this allows your Volt to take care of battery management chores using grid electricity instead of using its battery. Keeping your Volt plugged in will enable you to use all your battery miles for driving.

Interesting reading: http://cumminsengines.com/assets/pdf...whitepaper.pdf

Related Battery Degradation Information

Although cold weather will not degrade the battery, what many may not realize is degree of engineering sophistication the Volt employs to coddle the LiOn battery and minimize degradation from other causes while providing maximum battery life:

  • The battery is never fully discharged. Only 10.5 kWh (usually 45-50 miles in summer, 25-35 miles in winter) of the battery's total 16 kWh can be used (16.5 kWh for MY 2013). The extra 5.5 kWh forms a buffer as well as a reserve to be used as the battery ages. LiOn batteries degrade faster if fully discharged on a regular basis, the Volt prevents this.
  • The battery temperature is maintained in a narrow range while plugged in or driving. This is done with a liquid coolant system. Extended exposure to high heat is bad for battery life. The Volt minimizes the effects of external hot or cold temperatures by using its active thermal management coolant system programmed to stay within 3.6°F (2°C) of the pack’s optimal temperature, which depending on usage conditions falls in a range between 50ºF and 85°F (10ºC to 30°C). While it is parked unplugged, the insulation around the battery helps maintain the desired temperature.
  • The battery can not be cooked with a "supercharge". The Volt does not allow rapid, half hour recharges of the depleted battery. These kind of charges can easily cook the battery if done frequently or improperly.
Related reading: http://www.myperfectautomobile.com/g...nt-system.html
Also: http://en.wikipedia.org/wiki/Chevrolet_Volt#Battery

Volt buyers pay a little more to have these advanced battery management features. To sell at a lower price, some EV's skimp on these features or skip them altogether.

GM has test Volts with well in excess of 200,000 miles still operating within spec which means the liquid-heated and cooled battery and related systems are engineered to at least go the distance in all climates. Though the battery is warranted for half that, I expect we will see many Volts still running on their original battery even after 12-16 years of use.

Related reading: http://gm-volt.com/?s=micky

http://news.fleetcarma.com/2014/01/1...el-efficiency/
 

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This would be a good insert into the Owner's Manual. Dealerships should all read this. Nobody should buy a Volt without reading this. So that's my way of saying +1 :)
 

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Yes, would be nice for all the Chevy dealerships have this info also so they can tell potential and new buyers what to expect, and how to maximize their purchase. Or, at least have Chevy dealers know of this website to point potential buyers and new buyers to. :)
 

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A very good report but I would like to point out one little error.

When preconditioning even at 240V if the Volt is in comfort mode the car will consume more energy than the EVSE can put out. The Volt can only draw 3.3KW from the wall on a 240V charge but the heater can draw as much as 7KW of energy in comfort mode. The Defroster in comfort mode can even draw more than that (I've observed ~8KW peak). The balance has to come from the battery no matter if your plugged in at 240V or 120V. At 120V you are limited to 1.4KW from the wall when running at 12A setting. I pre-condition at 120V and even after 30mins (after the end of the remote start) on a cold morning with my car in comfort mode i'm fully charged again.

If you run in ECO then at 240V the heater runs ~3KW and the EVSE can keep up.

I have a 2013 with the power displays and it will show how much power is being drawn from the battery. I have observed these power usages. Also others on here have recorded in more detail the power consumtion of the HVAC system with DashDaq.

As a note if you are in fan only mode and you do a remote start the car will default to comfort mode during the remote start.
 

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Great post. Thanks. I experienced my first day of reduced range due to overnight low temps of around 40 degrees (cold for L. A.). Had to use 3/10ths of a gallon today. Not happy.
 
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EXCELLENT INFORMATION

Well done Sreverino. You spent a lot of time on this. Copy to all of my owners and lesees.
Required reading for all!
I
Best-

Thomas J. Thias

Sundance Chevrolet
 

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Discussion Starter #8
When preconditioning even at 240V if the Volt is in comfort mode the car will consume more energy than the EVSE can put out. The Volt can only draw 3.3KW from the wall on a 240V charge but the heater can draw as much as 7KW of energy in comfort mode. The Defroster in comfort mode can even draw more than that (I've observed ~8KW peak). The balance has to come from the battery no matter if your plugged in at 240V or 120V. At 120V you are limited to 1.4KW from the wall when running at 12A setting. I pre-condition at 120V and even after 30mins (after the end of the remote start) on a cold morning with my car in comfort mode i'm fully charged again.

If you run in ECO then at 240V the heater runs ~3KW and the EVSE can keep up.

I have a 2013 with the power displays and it will show how much power is being drawn from the battery. I have observed these power usages. Also others on here have recorded in more detail the power consumtion of the HVAC system with DashDaq.

As a note if you are in fan only mode and you do a remote start the car will default to comfort mode during the remote start.
I've made some adjustments. Thanks, Neromanceres. All the points could probably be much more detailed, but the intent is to give more of an overview. Even as an overview, it's probably longer than some would like :)
 

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Nice writeup. :) I will ask ChrisC to add it to the FAQ.

By the way, if you have any good writeups like this that I've missed sending to ChrisC, why don't you drop him a note with the URL and suggest he add them to the FAQ. He did add the write-up you made about the meaning of the different sounds the Volt makes to the FAQ.

WVhybrid
 

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Outstanding Write up. I have been a 2013 owner now for 2 months, and I wish I would have found this 6 weeks ago when the weather turned cold, and all I saw was 35 instead of 38-42 I was starting to get! I got the stall firmeware update, and then never saw higher than 35 again!!! I swear they put me back to 2012.... It likely was the weather, but keeping my fingers crossed. I think I should get 38 minimum and then draw faster or slower based on my driving, not having an ERR tell me based on my last 15 miles. Oh well, the car is smarter than me. I just don't think it needs to show off all the time. I am out smarting the motor kicking in buy adjusting my drive mode to ensure more EV miles.
 

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This explains exactly what I was wondering about my declining EV range estimate this week. Now I know the fully charged EV range is estimated based on recent trend, and just happens to be lower because I've been doing more freeway driving with the heat on and not because of a problem with battery capacity. Thank you for writing and posting this, I found it very informative.
 

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I let mine warm in the garage this morning. About 40 in garage but got phone call and forgot I started Volt. Lost 6 miles of battery buy the time I left. I thought the 240 would at least keep e en with the battery but I guess I was wrong.
 

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I got over 40 miles just on battery power today, which is more than I've been getting lately, even though today was colder!
it was below 35F so the car (a 2013) kept doing the ERDTLT thing (Engine Running Due to Low Temperature) which helps heat the system so the battery doesn't have to do it, and also recharges the battery a bit. Also all the driving was on local city streets. So because of those 2 things, I got a few more battery miles than usual.
 

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Added to FAQ. Thanks Steverino for the work in this post, and to WVhybrid for the PM alert to me to add this to the FAQ.

Which only took me over two months to get to. Thanks for your patience :)

I'll be reorganizing the FAQ (linked in my sig below) soon, because I want to post on a blog about it, so I need to make it more presentable ...

On the topic of this thread, my numbers skew lower than most. I have a short commute, so I have the luxury of doing whatever I want and still getting home under battery power. I put the car in Sport mode every time, I drive with a lead foot (jackrabbit starts out of every traffic light), the climate control is always in Comfort mode, and in winter I have the heat cranked (for whatever THAT is worth, the heater is anemic). The estimated miles I get out of the battery range from a high of 35 or so in the spring/fall, and 27 or so in the winter. That 27 miles is still plenty for my normal commute, although today I ran an errand at lunch and was down to a single (gulp) mile by the time I got back to work. I ended up having to steal some juice from an outlet in the parking deck (where we aren't allowed to plug in, long story). All because I don't want to burn gas anymore. I like having six months between fillups :)
bumper-sticker.jpg
 

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I've only had my 2013 a couple months and was wondering why it was telling me I only had 30 miles available on a full charge. After reading this post it makes a bit more sense. Thank you.
 

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I bought my '12 volt in Oct 2012 and after driving through the first Chicago winter season, I had a question for the forum members

I used to get 10.3 kwh battery energy consumed on a full charge early in fall (around Oct-Nov '12). However through the winter that has varied from 9.7-10.1 kwh on a full charge, I've haven't been able to get 10.3 kwh?

Curious, what's the experience of other forum members in cold climates. BTW, I don't think I ever got 10.5 kwh from a full charge.
 

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@voltrocks: Yes, I have been seeing a very similar drop off in total energy measured (on the center stack) before the car exhausts the pack and switches to gas. I think the highest I ever saw in ours was maybe 10.8kWh. Late last fall and this winter I saw numbers as low as 9.3kWh. I asked my Volt Adviser, but he was unable to explain whether the variation was a) an actual reduction in the energy from the pack, b) a reduction due to some load which taps off the battery before the point where this kWh meter makes its measurements.

Hope someone could shed some more light on this.
 

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Discussion Starter #18 (Edited)
@voltrocks: Yes, I have been seeing a very similar drop off in total energy measured (on the center stack) before the car exhausts the pack and switches to gas. I think the highest I ever saw in ours was maybe 10.8kWh. Late last fall and this winter I saw numbers as low as 9.3kWh. I asked my Volt Adviser, but he was unable to explain whether the variation was a) an actual reduction in the energy from the pack, b) a reduction due to some load which taps off the battery before the point where this kWh meter makes its measurements.

Hope someone could shed some more light on this.
My 2011 does not have this display. As I understand it, this kwh display depends on many factors. I think WOT or another moderator has tried to explain this in another post. If I can find it I'll post a link here.

OK, here are two relevant and related posts:
http://gm-volt.com/forum/showthread.php?19703-A-Tale-of-Two-Batteries&p=272265#post272265
(Basically a two Volt family, but one car getting a different kwh display thn the other using the same route. Start reading at post #46.

And here is the original story as it later appeared in a GM-Volt main page article:
http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/
 

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So, A Tale of Two Volts seems to suggest that the kWh reading is real. That's nice to hear.
[[I suppose most folks might say "Duh!", but while I do see the range reduced on ours (from when the kWh meter used to finish up at 10.x kWh last summer), I also know driver style changes and temperature could be variables. In fact, so far GM wasn't able to say that the pack capacity was not expected to be changed by temperature.]]

I haven't fully digested the other thread. However from the discussion on cell balancing and full charge-discharge cycles, I can only offer more details on our usage:
We use the car every day, and charge it every night. Most days we do not deplete the battery, so our general usage pattern is partial-discharge, full-charge.
That said, we do deplete the battery and have the ICE kick on now and then. I would say roughly once a week, perhaps a little less. We also take the car on longer trips where the pack is depleted and the ICE is on, and it might be a day or so before we can plug it in to permit the pack to charge.
I guess I might have to try some data collection of my own, and perhaps shift our charging behavior to run the pack down to the ICE kicks in each time. Of course, now that the weather is mild, if the kWh (and range) improves, I won't know for sure what the cause was.
 

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I guess I am also going to do some data collection too. Now that the weather warmed up a bit, the other day I got 48 miles on 10.1 kwh energy used before the ICE kicked in.

My theory for '11 and '12 Volts, since only 10.5 kwh of battery capacity out of 16 kwh is available, the range may vary depending on the weather and your driving style, but starting out from a full charge, we should always consume 10.5 kwh before the ICE kicks in.

I am still undecided if I should take my car to the dealer for a quick battery checkup.
 
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