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Discussion Starter · #1 ·
I have been waiting for some cold weather here in Maine so that I can observe how much power the Volt is drawing from our Voltec charging station (240V level 2) to maintain the battery temperature at a safe level. I have live monitoring equipment for temperature and charging current in Watts installed and have put together this chart showing the last seven days of charging power vs. outside temperature. My charging station provides approximately 3700 Watts to the Volt during charging, and you can clearly see the charge cycles as extended periods at that wattage. But you will also see short spikes of around 2500 Watts. My data logger samples every 10 minutes, so the spikes are between 10 and 20 minutes long. I am pretty certain that these brief power draws relate to battery temperature management, and so far it is not a great deal of power. These readings were taken in late December 2012, and Maine will get a lot colder in January 2013 when our temperatures dip below zero Fahrenheit at night quite often. I may post updated charts showing how much charging power is drawn on those very cold nights. I thought that Volt owners might find this information interesting, and it clearly points out that in extreme temperature environments it is wise to leave the Volt plugged in.
 

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Thanks for posting the chart.
One can never have too much info.
 

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I have been waiting for some cold weather here in Maine so that I can observe how much power the Volt is drawing from our Voltec charging station (240V level 2) to maintain the battery temperature at a safe level. I have live monitoring equipment for temperature and charging current in Watts installed and have put together this chart showing the last seven days of charging power vs. outside temperature. My charging station provides approximately 3700 Watts to the Volt during charging, and you can clearly see the charge cycles as extended periods at that wattage. But you will also see short spikes of around 2500 Watts. My data logger samples every 10 minutes, so the spikes are between 10 and 20 minutes long. I am pretty certain that these brief power draws relate to battery temperature management, and so far it is not a great deal of power. These readings were taken in late December 2012, and Maine will get a lot colder in January 2013 when our temperatures dip below zero Fahrenheit at night quite often. I may post updated charts showing how much charging power is drawn on those very cold nights. I thought that Volt owners might find this information interesting, and it clearly points out that in extreme temperature environments it is wise to leave the Volt plugged in.

Is your data logger integrating or point sampling? If is point sampling, like most of those I've seen, you really don't get a good idea how long the spikes are.. The could be 10seconds every 10min.. and look like they are on for every sample.
 

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Can WOT chime in here? This brings up some questions I have concerning EVSEs and the battery thermal management on the Volt. This would seem to imply the 3.3KW charger is either separate from the TMS system, (which would lead me to believe that an EV with TMS needs a higher duty cycle on the EVSE than just what can be accounted for with the charger rating) or the charger can handle about 10% more power than rated.

Can the Volt draw more power than 3.3KW rating to account for separate TMS functions or does all the power flow still flow through it?
 

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Discussion Starter · #5 ·
Good point tboult,

Yes, these are point samples. So I reviewed the raw data and found a few instances where there were 2 consecutive readings 10 minutes apart. From this I can only assume that sometimes the Volt is drawing about 2500 Watts for at least 10 minutes, but I really can't tell how much less than 10 minutes it is. Given the ratio of consecutive readings to single readings, I would hazard a guess that the average time is the range of 5-10 minutes.

Is your data logger integrating or point sampling? If is point sampling, like most of those I've seen, you really don't get a good idea how long the spikes are.. The could be 10seconds every 10min.. and look like they are on for every sample.
 

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I'm in a much warmer zone so I use the much "higher tech" audio method: when I go out to the garage, I listen to the car for either silence or the gentle whir of the cooling fans. This time of year after the charge, it's usually silent. :)

Thanks for the research data! :cool:
 

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I have been waiting for some cold weather here in Maine so that I can observe how much power the Volt is drawing from our Voltec charging station (240V level 2) to maintain the battery temperature at a safe level. I have live monitoring equipment for temperature and charging current in Watts installed and have put together this chart showing the last seven days of charging power vs. outside temperature. My charging station provides approximately 3700 Watts to the Volt during charging, and you can clearly see the charge cycles as extended periods at that wattage. But you will also see short spikes of around 2500 Watts. My data logger samples every 10 minutes, so the spikes are between 10 and 20 minutes long. I am pretty certain that these brief power draws relate to battery temperature management, and so far it is not a great deal of power. These readings were taken in late December 2012, and Maine will get a lot colder in January 2013 when our temperatures dip below zero Fahrenheit at night quite often. I may post updated charts showing how much charging power is drawn on those very cold nights. I thought that Volt owners might find this information interesting, and it clearly points out that in extreme temperature environments it is wise to leave the Volt plugged in.

Very very nice post! I love the information. Keep up the good work and I look forward to seeing what you learn in the colder weather to come.

I am curious, is your Volt outside or in a garage?
 

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when I go out to the garage, I listen to the car for either silence or the gentle whir of the cooling fans.
I love the weird sounds that my Volt makes sometimes, while it's plugged in, especially (but not only) when pre-conditioning. It freaks out my wife and kids but I've long been a musician and fan of weird music so it sounds wonderful to me. Sometimes it's like a mad angry electronic Siamese cat -- when I was a kid my parents had a real (not electronic) Siamese cat and it would do things like a sort of cross between a growl, a moan, and a purr sometimes.

hey i think I'll start a new top-level thread on this topic...
 

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Discussion Starter · #9 ·
Thanks montgom626. I'll add mode details to my web page (and here) as the temperatures drop in Jan/Feb 2013.

My Volt is in car port (see details on my blog) catching a little snow today.

Very very nice post! I love the information. Keep up the good work and I look forward to seeing what you learn in the colder weather to come.

I am curious, is your Volt outside or in a garage?
 

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While I do not have VOLT only energy usage from my smart meter, I do have data that shows with a fully charged battery my overnight total house energy use by hour remains in a 0.64-0.74 kWh range for the whole house at temperatures under 32 degrees this time of year. That includes the VOLT plugged in 120v outlet, furnace, two refrigerators, outdoor lighting (about 14 cfl bulbs, yes I know that is a lot but it is a look as well as security). So overall I consider the VOLT "battery warming" to be low in sustained energy usage in cold temps.
 

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Discussion Starter · #11 ·
Updated charging Watts vs temperature data

The temperatures here in Maine dropped below 0F last night (to -2F) and I recorded the charging vs temperature data from my dataloggers and compiled them into a nice clear chart that correlates the frequent energy draws from my Voltec charging station to warm the battery with the vehicle temperature. This paints a very clear picture of the thermal management energy usage. Considering how cold it was - it's not a great deal of energy. (My Volt is in an open car port - as seen in my blog)
 

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