Does anyone know how the batteries handle cold climates when the vehicle is parked but not plugged in?

Example: I drive to work, and stay there for 8 hours. It's -10 below out and real windy, and the car isn't plugged in.

Does the battery just have to deal with that, do they cycle the generator, or do I have an option?

Contrary to popular belief, it doesnt cycle the generator for heat as there is no physical connection between the ICE coolant and the battery coolant. Although it has limits the battery box has been designed to have a high enough insulation factor to limit the heat loss of the battery over a typical overnight soak, unplugged, in sub-zero weather. (and reported as such here at gm-volt last year during the Kapuskasing cold weather tests apparently down to -13F/-25C )

Once powered ON there is an 360-volt electric circulating heater system that operates directly off the Lithium Ion battery to circulate battery coolant to quickly warm itself!

WopOnTour

Contrary to popular belief, it doesnt cycle the generator for heat as there is no physical connection between the ICE coolant and the battery coolant. Although it has limits the battery box has been designed to have a high enough insulation factor to limit the heat loss of the battery over a typical overnight soak, unplugged, in sub-zero weather. (and reported as such here at gm-volt last year during the Kapuskasing cold weather tests apparently down to -13F/-25C )

Once powered ON there is an 360-volt electric circulating heater system that operates directly off the Lithium Ion battery to circulate battery coolant to quickly warm itself!

WopOnTour

Thanks for the informative post WOT. My next concern is parking in an airport lot for a week. I guess maybe I should just try to avoid that scenario?

Work has me traveling to various places 1-2 weeks at a time in the short term. I suppose I can opt for a ride from a friend instead of leaving my Volt there.

Contrary to popular belief, it doesnt cycle the generator for heat as there is no physical connection between the ICE coolant and the battery coolant. Although it has limits the battery box has been designed to have a high enough insulation factor to limit the heat loss of the battery over a typical overnight soak, unplugged, in sub-zero weather. (and reported as such here at gm-volt last year during the Kapuskasing cold weather tests apparently down to -13F/-25C )

Once powered ON there is an 360-volt electric circulating heater system that operates directly off the Lithium Ion battery to circulate battery coolant to quickly warm itself!

WopOnTour

Actually, here's the link WOT was referring to: http://gm-volt.com/2010/02/23/chevy-volt-cold-weather-testing-update/

It does appear that the generator is used to warm the batteries though, at least according to the information here. Is that no longer the case WOT? I know you seem real informed, but I don't recall hearing where you get all this information. I suspect you're employed by GM. :)

Uh, I don't think he's been hiding it. :)

See also the thread about the Volt battery temperature range (http://gm-volt.com/forum/showthread.php?5243-Volt-thermal-management-system-temperature-band/). Although that's really just for background. I don't think we have a firm answer to your question, other than the fact that GM has tested to extremes colder than what you described.

The owners manual would lead you to believe you could get stranded with a cold battery. Page 5-41:

"BATTERY TOO COLD, PLUG IN TO WARM"

"This message displays during extremely cold temperatures, when the vehicle will not start until the high voltage battery is warm enough.
Plug the vehicle in to allow the charging system to warm the high voltage battery, then the vehicle can be started"

The owners manual would lead you to believe you could get stranded with a cold battery. Page 5-41:

"BATTERY TOO COLD, PLUG IN TO WARM"

"This message displays during extremely cold temperatures, when the vehicle will not start until the high voltage battery is warm enough.
Plug the vehicle in to allow the charging system to warm the high voltage battery, then the vehicle can be started"

Interesting; do they specify anywhere else a numerical temperature to correspond to "extremely cold"?

Again, I point you to the battery temperature thread that I linked to above.

However, even if you read through that thread (including Charles Whalen's formidable commentary :) ) you'll see we don't yet have concrete temperature ranges, and certainly not at the low end. We're pretty sure that, when plugged in, the Volt is designed to operate properly (meaning meet its design performance) at temperatures as low as -13 degrees Fahrenheit (-25 C).

However the question above is for -10 deg F and NOT plugged in. I don't know. Maybe WOT does, or if not then we'll find out soon enough ... Well, soon enough for me, as it's just an academic exercise for me. If it's a cold day in DC in December, that will be the coldest temp my Volt ever sees, because I will promptly drive it 600 miles south. In Atlanta we have maybe a dozen hours per year below +15 deg F.

Somewhat related to this topic, there is a thread over at Leaf.net that details what is NOT covered in the Leaf battery warranty.

It will be interesting to see how the Volt's warranty compares...though when I read through this list, I'm glad GM went with a more conservative approach to SOC and liquid cooling.

LITHIUM-ION BATTERY
This warranty does not cover damage or failures resulting from or caused by:
 Exposing a vehicle to ambient temperatures above120F (49C) for over 24 hours.
 Storing a vehicle in temperatures below -13F (-25C) for over seven days.
 Leaving your vehicle for over 14 days where the lithium-ion battery reaches a zero or near zero state of charge.
 Physically damaging the lithium-ion battery or intentionally attempting to reduce the life of the lithium-ion battery.
 Exposing the lithium-ion battery to contact with a direct flame.
 Charging the lithium-ion battery full on a daily basis despite the lithium-ion battery keeping a high state of charge level (98-100%).
 Immersing any portion of the lithium-ion battery in water or fluids.
 Opening the lithium-ion battery enclosure or having it serviced by someone other than a Nissan LEAF certified technician.
 Neglecting to follow correct charging procedures.
 Use of incompatible charging devices.
 Consequential damage caused by the failure to repair
an existing problem.

Charging the lithium-ion battery full on a daily basis despite the lithium-ion battery keeping a high state of charge level (98-100%).

I wonder what Nissan means by this? You can't go on vacation for two weeks and leave it plugged in the whole time? Isn't the charger smart enough to know the car doesn't need a charge if it is above a 98% state of charge?

Does the Volt user manual recommend against leaving it plugged in for days or weeks?

I think, what Nissan would want is for you to partially charge the battery before going on vacation, but then unplug the car while you're gone. Keeping the battery at a high SOC (for days) will decrease its life and this seems to be what they're worried about. This is one of the main reasons that GM has limited the max. SOC to something less than 85%.

As for Volt battery conditioning...
My guess is that if there is sufficient SOC in the battery, it will use that power for heating/conditioning as described by WOT and the ICE won't run unless SOC dictates that it must...(i.e. 20-25% SOC).

So, if you park the car at the airport with 25% SOC and let it sit for a few days in the cold, it will likely be at or below 20% SOC when you return to the car....as soon as you hop in the car to drive, the ICE should fire up, charging the battery (slightly) and producing electricity for battery conditioning and the traction motor.

I can't imaging that the engine could/would every start (on it's own) just to condition the battery. This would not be safe, as the vehicle does not know if it's indoors...

Page 10-24 of the manual says:
“Keep vehicle plugged in, even when fully charged, to keep the high voltage battery temperature ready for the next drive. This is important when outside temperatures are extremely hot or cold.”

On page 10-25 under Extended Storage it says:
“to avoid potential damage to the high voltage battery, perform the following recommended steps:
Store the high voltage battery with ½ charge or less.
Always store the vehicle in an environment between -10 deg C (14 deg F) and 30 deg C (95 deg F).
Vehicle storage at extreme temperatures can cause damage to the high voltage battery.”

“Extended storage”, however, is not defined.

GM's recommendations for long term storage are pretty standard for Li batteries, based on self discharge rates.

It's somewhat hard to determine what a Volt's self discharge rate will be, but let's assume 2% per day (in addition to battery chemistry, ancillary vehicle loads and cell temperature will affect this).

If the car were stored at a 50% SOC per the owner's manual, the battery should last 46 days before hitting a 20% SOC. It seems that GM has determined that 20% is the lower safe cut-off, though if the SOC dipped a bit below 20%, it probably wouldn't be the end of the world.

Completely discharging the battery is what GM is trying to avoid, which is why they say not to store the car unplugged. Given enough time, the Volt's battery would fully discharge and irreversible damage to the cells could occur.

Here's a little chart:
I was sloppy and didn't label my axis, but X = Days, and Y = % SOC
http://i10.photobucket.com/albums/a141/jkirklin/dishcargerate.jpg

The Owners Manual states on page 9-44 under Charging:

It is recommended that the vehicle be plugged in when temperatures are below 0 degrees C(32 degrees F) and above 32 degrees C (90 degrees F) to maximize high voltage battery life.

The charging system may run fans and pumps that result in sounds from the vihicle while it is turned off. Additional unexpected clicking sounds may be experienced caused by the electrical devices used while charging.

The Leaf battery warranty does not cover damage or failures resulting from or caused by:
Exposing a vehicle to ambient temperatures above120F (49C) for over 24 hours.
Storing a vehicle in temperatures below -13F (-25C) for over seven days.
Leaving your vehicle for over 14 days where the lithium-ion battery reaches a zero or near zero state of charge.
Charging the lithium-ion battery full on a daily basis despite the lithium-ion battery keeping a high state of charge level (98-100%).


Thank you JeremyK for that excellent information! We can see now that while Nissan has matched GM on the headline terms of the battery warranty (8 years, 100000 miles), the devil is in the details. Nissan has proscribed some behaviors that will violate the warranty; GM is babying the battery when they can and NOT putting these kinds of exceptions in the warranty. You do whatever you want, and GM is confident that their battery will survive because most of the time it's getting treated so well.

No problem. I occasionally peak at Statik's site to see what's going on. Basically, Nissan is allowing the customer to come very close to voiding the warranty even though it would be easy for them to place electronic limits within the system that would protect the customer. Interesting strategy.

As we're beginning to see, this is the only way they can claim a 100 mile range.
Also on his page, but off topic...Leaf deliveries delayed until Jan. 2011.

The Volt engineers are looking smarter all the time. If you were going to park the Volt at the airport for a month in the middle of winter, all you would have to do is run it in Mountain Mode prior to parking the car. That would keep the battery SOC nearer to the 50% optimal charge state for long term storage, rather than letting it sit at 20-25% SOC during the same period.

My wife and I spend Jan. through April in Florida. I would leave our Volt in our house garage near Detroit. It rarely gets below 0 F. here, but it will sit in a cold environment for 3 1/2 months. I was told to store it with the Lithium Ion battery low on charge and to charge and remove the 12 volt battery. Does this all seem OK?

I wonder if GM offered a solar panel, would it provide enough power to condition the battery during the heat of the day? I've done some back of the envelope calculations that show a contoured roof solar panel could provide 3-5 miles of additional EV range, so I'm thinking it would. Could be a very useful option for hot climates like AZ and CA. Just a thought.

Prius offers an optional contoured solar roof panel, and all it powers is a fan to keep air moving through the cabin on a sunny day. I doubt it would produce 3 to 5 miles.

Absolutely...I did the same calcs a while back and came up with about 2-3 extra miles per day in MI. You could double that range for some areas of the extreme SouthWest. That's assuming a 20% efficient panel.

http://cleantechlawandbusiness.com/cleanbeta/wp-content/gallery/cache/86_watermark_520x420_us_pv_annual_may2004.jpg

"Prius offers an optional contoured solar roof panel, and all it powers is a fan to keep air moving through the cabin on a sunny day. I doubt it would produce 3 to 5 miles. "

The Prius solar panel option is a gimmick. A modern, high efficiency, 1 sq meter panel should provide a few miles of additional range OR some extra energy for battery conditioning.

Great map Jeremy. thanks! This idea could work well for those who park in a wide open parking lot with an unobstructed view of the south sky all day while at work. Not so much for those on city street parking or in parking ramps / garages.

I work at home with too many big trees. I had solar experts come over to bid on a roof system and they said even my house roof is too shaded by trees to the south to make it worthwhile. So either I have to move or I have to fire up the chain saw.

I did the same calcs a while back and came up with about 2-3 extra miles per day in MI.

That graphic you posted says "flat plate, facing south, latitude tilt." Those are some major assumptions there. You start applying actual factors (not flat anymore, imperfect southern exposure, horizontal not tilted) and suddenly you've lost 80% of your production.

I do think that PV efficiency will get to the piont of providing some usefulness in a car roof application, but for now it's just a gimmick.

I'd like to start a new thread for this topic and was simply doing "back of the napkin" calcs...but if you want to see the numbers

Average (FLAT PANEL) Solar Insolation for Lansing, MI: 3.8 kWh/m2/day
Thin film solar panel efficiency: 20% (this should probably be 15%)

Potential Energy Output per day: 760 Whrs
Average Wh/mile consumption: 250 Whr/mile
Range increase before charging/conversion losses: 3.04 miles
Range with 80% combined charge/discharge/conversion efficiency of power electronics: 2.4 miles

This is for MI. I think it's feasible, considering GM is willing to pay around $1000 per usable kWh of battery capacity.

What's the typical power consumed to condition the Volt's battery during the heat of the day in a hot climate like Dallas Texas or Tuscon, AZ? WOT do you know? For battery life, it's the heat that gets you right?

Over in the "kWh to charge" thread (http://gm-volt.com/forum/showthread.php?5610-How-Many-KWh-to-Charge-the-Volt) we are hoping somone will hook up a kill-a-watt to their 110V charger (or carefully monitor their dedicated meter) and figure out what these conditioning and other parasitic loads are. It shouldn't be long until one of those guys has a chance to do just that.

As a general rule for lithium ion:

At the high end of the temperature range (heat) you are killing the long term life of the battery.
At the low end of the temperature range (cold) you are killing the short term performance of the battery.

The latter means that you'll get out to the cold car and discover that it only has 20 miles of range. Or, rather, it might say it has 40 miles, but after you go 10 miles half of that original range has vanished. Or it can't deliver the power that it normally could, so you won't have the acceleration performance you'd be used to. These issues with cold are all short term problems, not affecting the long term life of the battery

All of these are handwaving numbers. We haven't seen any actual official numbers from GM yet, and YMMV. It'll be a fun winter :)

There is a Prius conversion to an actual "solar" prius....the thin film panels can yield up to a 6 mile range on this thing supposedly...

http://www.youtube.com/watch?v=9Jsqf5CEUI0

Here the NY times said the solar prius conversion panels can give 20 miles but I know that can't be true in one day as you'd have to have it in the sun for several days.....

http://green.blogs.nytimes.com/2009/01/07/solar-powered-cars-not-just-yet/

http://green.blogs.nytimes.com/2009/01/07/solar-powered-cars-not-just-yet/

What's the typical power consumed to condition the Volt's battery during the heat of the day in a hot climate like Dallas Texas or Tuscon, AZ? WOT do you know? For battery life, it's the heat that gets you right?
Rooster,
I don't have actual electrical current numbers to share. The BMS is going to implement 3 potential measures depending on the actual temperature delta (actual T to that desired for charging) that exists. So the amount of current drawn by the BMS for temperature conditioning is obviously highly variable. Obviously it will be easier to MAINTAIN the battery temperature, than to significantly alter it. So if the car was plugged in immediately after driving the battery temps will already be relatively stable and maintaining them as such less an issue even as ambient conditions become increasingly influential. When things are stable generally there will always be a small amount of heat to dissipate while the battery is being recharged. The standard (stable at/near desired T) cooling loop will circulate the coolant out to the front of the car where the battery radiator and variable speed fan/s will provide temperature stability.

If the car was plugged in AFTER the temps had stabilized to ambient the levels of intervention required ARE going to be more costly in terms of power usage. If the temperatures are significantly too cold, the battery radiator is temporarily bypassed, and the coolant loop effectively shortened, at which time the 360 volt heating element within the battery pack will aggressively warm coolant to bring the temps up to those ideal for charging.

If the temps are too HOT another alternate coolant loop is implemented permitting battery coolant to flow through the chiller that is cooled by running the 360 volt refrigerant compressor (variable speed) to quickly lower cell temps to those ideal for charging. Once charging commences maintaining stability might require occasional intervention from either the "quick" cooling or heating loops, depending of course on the severity of the conditions.

I have finally completed a detailed article on the Volt's various coolant loops and have forwarded it to Lyle for proofing. I would expect it should make it to the main page sometime in the near future.

Regards
WopOnTour

Great info! Will this be the same article as the battery article you also mentioned was pending, or a separate one?

FYI, ChevroletVoltage just posted a couple "Ask Alexandra" videos, and the battery temperatures are discussed in the second one. I've revised my post above.

Boing is going into mass production with a solar cell that achieves >39% efficiency.
http://www.renewableenergymagazine.com/paginas/Contenidosecciones.asp?ID=15&Cod=6759&Tipo=&Nombre=PV%20Solar%20News

With the right cells, solar charging would be very feasible.

WOT,

Do you think you could elborate on why the engine turns on due to low temperatures, even if the battery's at 100% and the car preconditioned before leaving for a trip? I know you had mentioned that the battery heating isn't connected to the ICE, so I'm curious as to the reason why the engine turns on in lower temperatures in all-electric/Charge depletion mode.

Thanks!

WOT can comment further, but it's already been said. The ICE fires up to provide power for the battery TMS to heat up the battery in a hurry.

The ICE coolant loop and the battery TMS coolant loop are indeed separated so there no heat flow from the ICE to the battery that way, but there is power being generated by the ICE and generator so that it can heat up the battery without sucking energy out of the battery.

There is some discussion of this in the "battery temperature thresholds" post, linked from the FAQ:

http://gm-volt.com/forum/showthread.php?5243-Volt-thermal-management-system-temperature-band&p=48601#post48601

- Chris

P.S. I'm getting caught up with the forum .... :)

Thanks Chris.

The confusing part to me, anyway, is just that if I have the vehicle plugged in for a long time prior to leaving, and I precondition it, the ICE still turns on for a couple minutes after I drive away and then can stay off for quite some time. If it only needed such a small amount of power, why not just pull it from the wall after the remote start function was initiated? (2 minutes of ICE power would seem roughly the same as 15 minutes of remote start power at 220V. Maybe that's an invalid assumption though, mumble mumble.)

I may be wrong, but it seems like the people experiencing this are charging in a relatively warm garage and the driving out into a somewhat colder outdoors. Could that have something to do with the effect?

I may be wrong, but it seems like the people experiencing this are charging in a relatively warm garage and the driving out into a somewhat colder outdoors. Could that have something to do with the effect?

I visited my parents for a week and the Volt spent its time in a detached unheated garage. I saw the same behavior there, which makes me think there may be more to it than a warmer garage.