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Discussion Starter · #1 ·
I read that the Volt should always be plugged in (something about keeping the battery at the correct temperature, especially in hot and cold weather). So, if it is already fully charged, is the electric company still charging me because it is plugged in? Thank you in advance! This forum is great!
 

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There are two reasons to keep it plugged in: charging, and keeping the battery cool or warm. After being recharged, the car will be idle unless it needs to chill or warm the batter to keep it at an ideal temperature of 68°F to 72°F. Below that and the car will heat the battery while plugged in, above it and the car will cool the battery instead. While either is happening, yes, you'll be using electricity to pamper the battery. See http://gm-volt.com/forum/showthread...ent-system-temperature-band&p=48601#post48601
 

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There is some very small amount of energy being used when it's plugged in and not charging or doing something else (more on that later). This is so little that it's not worth worrying about. Your TV is probably using 10X more when plugged in and turned off.

However, the Volt may need to heat or cool the battery or to run a pump. When this happens yes you will use electricity from the wall even if the Volt is not charging. Normally this happens rarely and in any case there isn't a lot of usage involved. If the car is in an unheated garage in Ohio I'd think the usage would be minimal over the course of a year.
 

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The EVSE may use standby current of the order of milliamps. For example, my CT500 has an internal cell modem to upload usage data to ChargePoint.

The charger in the Volt may turn back on if the battery's temperature management system (TMS) is activated to maintain battery temperature in the optimal range.

The charger will turn back on if you use the key fob or remote link to precondition the car.

I am not aware of any other power company loads associated with the Volt and/or its EVSE.

KNS
 

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I read that the Volt should always be plugged in ..So, if it is already fully charged, is the electric company still charging me because it is plugged in? ....
Great Question DogMOM and welcome to the Forum. The device that connects your Volt to your household outlet (120 Volt) is called an EVSE. It consumes approximately 2 watts when plugged in if the car is fully charged. To translate, if you leave it plugged in all the time, and the car is already fully charged, it costs you 1 Kilowatt Hour every 5 weeks. you probably pay $0.10 to $0.25/ per Kilowatt hour for you electricity.....

When the volt is fully charged, it communicates with the EVSE and tells it to disconnect the power lines. If you are standing near by when this happens, you can hear the EVSE click as it opens the power relays.

once the car is "fully charged" your Volt can turn the EVSE back on if it wants more power, as you note, for battery thermal management. Battery Thermal Management happens if it is colder than 20 degrees F outside
(approximately) or if it is warmer than 75 degrees F. (approximately) The power used is fairly small, and is good for your battery range for the next drive. In either case, if the Battery thermal management system wants to run, it will command the EVSE to reconnect the power. I don't know the power usage amount, but others here may. The amount used will vary with the temperature.

leaving the car plugged in also allows you to prestart the car and warm it up or cool it down while still plugged in before you next drive without using much battery range up in doing so....
 

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Battery Thermal Management happens if it is colder than 12 degrees F outside or if it is warmer than 80 degrees F. (approximately)
To be clear, it's the temperature of the battery (not the outside temperature) that is used to determine whether the battery needs warming or cooling. The battery has 400 lbs of mass and is surrounded with insulation.

Code:
Volt battery temperature management system (TMS) modes

Temperature range   | Volt is parked       | Volt is parked       | Volt is powered on
                    |  and plugged in      |  but NOT plugged in  |  (e.g. being driven)
--------------------|----------------------|----------------------|----------------------
                    |                      |                      |
above 122 F         | cooling(1)           | cooling(1)           | car won't run until battery
                    |                      |                      | is cooled below 122 F by TMS(2)
                    |                      |                      |
122 F .. 86 F       | cooling(1)           | cooling(1)           | cooling(2)
                    |                      |                      |
 86 F .. 72 F       | cooling(1)           |                      | cooling(2)
                    |                      |                      |
 72 F .. 68 F       | no action -- ideal temperature band for long-term life
                    |                      |                      |
 68 F .. 25 F       |                      |                      |
                    |                      |                      |
 25 F .. 14 F       | warming              |                      | warming(3)
                    |                      |                      |
 14 F .. -13 F      | warming              |                      | warming(3)
                    |                      |                      |
below -13 F         | warming              |                      | car won't run until battery
                    |                      |                      | is warmed above -13 F by TMS(3)

* Notes:
(1) High temperature cooling will only run if the SOC is >75%.  If the SOC is <75% then there is no action.
(2) At extreme high temps, the ICE may come on to generate power for the TMS to work faster,
  but only if the car is powered on (that is, the ICE won't start by itself, unmanned)
(3) At low temps, the ICE may come on to generate power for the TMS to work faster, and to generate
  power for the cabin heater, but only if the car is powered on (that is, the ICE won't start by itself; it will
  only start once the car is powered on or it receives a remote-start command);  the ICE will shut off once
  it reaches 150 F.  Note that the ICE coolant can not be used to directly heat the battery because the
  battery coolant loop is separate.
The above is for regular operation. If you are putting the Volt into storage for an extended period, without plugging it in, the manual says (on page 10-25) that ideally you should store it where the temperature range will be within 14° F .. 86° F. Traction battery SOC should be at 50%, and the 12 volt battery should be disconnected or on a trickle charger. Note that this is for long-term storage, not just parking it for a few days or even weeks.
 

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There are two parts to a basic EVSE: 1) A J1772 protocol board that is best left always on. This is the part of the EVSE that communicates with the device on the other end to exchange control information (Are you ready? How much power can I draw/send? Send power. Stop sending power, Stopping power. Starting power, etc) 2) The second part is a rather dumb relay that connects/disconnects power to the connected device.

In the case of the Volt, the car can request power for a variety of reasons such as charging batteries, pre-conditioning and maintaining battery temperature. When it is not doing any of these, it tells the EVSE it does not need power, and the EVSE disconnects the main relay. In this mode (relay disconnected), the EVSE is drawing a negligible amount of power which is the absolute minimum required to operate a few LEDs and the J1772 protocol board itself. Because this draw is very low, many basic EVSEs do not come with a power switch. For an CC LCS-25, measurements have shown that a full year of keeping the device always connected costs no more than 10 bucks or so. Keeping the EVSE on and connected to the device is recommended by GM because the Volt may request some power in future because of one of the situations described above. I the EVSE was completely "off", it would not be able to respond to these requests, and the Volt would not get the required power.

Some EVSEs offer additional services like network connection, monitoring, security, reporting, LCD panels, touch screens, card swipers/readers, etc. These add-on services would consume more power than a basic EVSE, and the amount of extra power drawn depends on the exact model and services that are being used.
 

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and generally if you have an EVSE in a covered but open outside area that little bit of power the EVSE is using will keep the unit dry.
 

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I can confirm the STOCK EVSE 1-2 Watt draw with the EVSE plugged in, but not connected to the car/car has finished charging. I put it on a kill-a-watt meter to verify. I have never had it draw power again once it was done charging - the only other power draws I have verified is that it does draws 880 watts and 1320 watts depending on the charging rate settings in the vehicle. Which makes sense since 110 x 8 = 880 and 110 x 12 = 1320. Although the 12A setting seems to fluctuate more than the 8 amp setting. Because of all the posts about the kill-a-watt meter's melting I discontinued testing the volt with it.

FWIW, my truck's block heater draws 800 watts. (and it is rated for 1000).
 

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Digging through the circuitry on my OpenEVSE kit I've got on the table here the power supply can only draw a maximum of 100ma (about a watt). Unless the car has asked for power and closed the relays, that's all it is drawing.
 

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Discussion Starter · #12 ·
Awesome! Thanks -- the electrician is due any minute to talk to us about a charging station at our home. I'm wondering if the Volt power cord that came with it can plug into a 240 outlet, or do we have to buy that $500 charging station part online . . . .
 

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... the electrician is due any minute to talk to us about a charging station at our home. I'm wondering if the Volt power cord that came with it can plug into a 240 outlet, or do we have to buy that $500 charging station part online . . . .
the short answer is no the stock EVSE is 120 volt only (level 1), there are more complicated answers possible. (some owners have torn the stock EVSE apart and modified it to work at 240 volts. )

There are many brands of Level 2 (240 Volt) EVSE available, most have been reported to be very reliable, (oddly enough, except for some of the ones that Chevrolet licensed to be co-marketed with the Volt in 2011 and 2012)


But I recommend having the electrician install a dryer style outlet and buying an EVSE model that can be plugged into it.
Clipper Creek makes some models as do other companies. This solution provides you with a lower cost installation and flexibility in use.
you next question may be "which model" or "what power level" since your Volt is perfectly happy charging at it's maximum 15 amps, should you buy a 25 amp or 30 Amp EVSE. That depends on you- if you intend or think you might buy a Spark or Leaf with a higher charge rate in the future, or a 2016 Volt which may or may not come with a higher rate charger, then buy a 25 amp or 30 amp level 2 (240 Volt) evse, otherwise, 15 Amp or 20 amp is fine.
 

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There are two reasons to keep it plugged in: charging, and keeping the battery cool or warm. After being recharged, the car will be idle unless it needs to chill or warm the batter to keep it at an ideal temperature of 68°F to 72°F. Below that and the car will heat the battery while plugged in, above it and the car will cool the battery instead. While either is happening, yes, you'll be using electricity to pamper the battery. See http://gm-volt.com/forum/showthread...ent-system-temperature-band&p=48601#post48601
I do not dispute your comment about the battery being kept at the ideal temperature, but that makes me wonder about what I am seeing. I live in a cold northern state and my Volt is always kept in an unheated garage overnight, where the temp in the garage is never below 32, and it is always plugged in. Now that I am completing my first year of ownership, and have experienced all 4 seasons here, and now that the nightly low temps are in the 50s and 60s, as opposed to zero or teens, my morning range has gone from about 38 miles..during the cold months, to now 46 miles as recently as yesterday. So if being constantly plugged in it to keep the battery at optimum temp, thus range too, I wonder why I am seeing such an increase in range with the warmer weather? Just trying to understand what is going on with the battery as it relates to temps and being plugged in. I would think that if the battery is kept warm, in the cold months, or cool in the hot months, it should offer the same morning range regardless of the season. Am I wrong?
 

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I do not dispute your comment about the battery being kept at the ideal temperature, but that makes me wonder about what I am seeing. I live in a cold northern state and my Volt is always kept in an unheated garage overnight, where the temp in the garage is never below 32, and it is always plugged in. Now that I am completing my first year of ownership, and have experienced all 4 seasons here, and now that the nightly low temps are in the 50s and 60s, as opposed to zero or teens, my morning range has gone from about 38 miles..during the cold months, to now 46 miles as recently as yesterday. So if being constantly plugged in it to keep the battery at optimum temp, thus range too, I wonder why I am seeing such an increase in range with the warmer weather? Just trying to understand what is going on with the battery as it relates to temps and being plugged in. I would think that if the battery is kept warm, in the cold months, or cool in the hot months, it should offer the same morning range regardless of the season. Am I wrong?
You are trying to tie the Volts estimated range and the temperature of the battery together. But they are not directly related. The estimated range is based upon your recent real world driving and the range you are getting. Energy used while plugged in to warm or cool the battery does not figure into this calculation. You are seeing increased range now that your weather is warmer because the Volt battery chemical reactions are optimal in mild temperatures (70's - low 80's) and when no heat or cooling is required while running on battery.
 

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You are trying to tie the Volts estimated range and the temperature of the battery together. But they are not directly related. The estimated range is based upon your recent real world driving and the range you are getting. Energy used while plugged in to warm or cool the battery does not figure into this calculation. You are seeing increased range now that your weather is warmer because the Volt battery chemical reactions are optimal in mild temperatures (70's - low 80's) and when no heat or cooling is required while running on battery.
Thanks for the reply, but I do not see how that answers my question, I am no engineer so it is probable me being dumb. If the battery is kept at optimum temp. when plugged in (winter or summer), what difference does the ambient temp make? Isn't that the entire point of the battery temp being maintained by the system, when plugged in? I am confused. haha
 

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The big draw is the electric heat for the passenger cabin in the winter. At 6kw of power when full on that's more than 50% of your total kWh in one hour. If you drive slowly you could be using more power to stay warm than to move the vehicle.
 

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Plus the set points are to keep it from getting too hot or too cold - The battery is not always going to be at the optimum temp for best max energy output.

A tight temperature control system would use more power
 
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