Electricity draw when plugged in for cold?

[dmen]

Does anyone have their L2 separately metered or with another way to see how much is being drawn? Particularly anyone in the Midwest or Northeast? I'd like to know how much energy is used by the TMS on a typical cold night. So like if your car is set with a value charge, how much does it draw to fight the cold while waiting to charge? Does it draw constantly or intermittently? And how much does it draw while preconditioning for a go-time?
Thanks.

 

[jmueller065]

Mine is set to a separate meter and I'm in the Detroit area so I guess I'd fit your requirements. Although I've never really taken a look at the current draw....let me go look now
(car is currently sitting outside in the cold; although its sunny out but the car is in the shade; and its 28F out and very windy; with only ~30% charge on it waiting to charge at 1am). In this situation it should only be drawing current to keep the battery warm.
Alas my smart meter only shows a counter of kWh consumed (looks like 654 kWh consumed since they put the meter in back in early June). Thus I will have to check it at regular intervals and do the math. The EVSE does indicate that its relays are on and that its providing power to the car though.

 

[jmueller065]

Very interesting; as I watch it more closely this weekend it seems to be charging as a way to stay warm?

I have the value charge set to charge at 1am every day. Yesterday and today when I plug in after driving it says "waiting to charge" in the car and online, but if I check it a few times over the next 30 minutes or so it charges up by a few % and then stops, finally waiting until 1am to complete the charge.

 

[jmueller065]

Update: Despite the car's charge going up the meter hasn't budged from its reading the past 45 minutes (e.g. in 45 minutes the car has used less than 1kWh worst case).
Will keep watching today.

 

[jmueller065]

Update 2: Car is now 7% higher in charge (from 86% to 93%), and power meter is +1 KWh (granted car wasn't discharged much but still it shouldn't be charging at all).
Temp outside: 25F and windy.

 

[jmueller065]

Update 3: Car is now 3% higher in charge (96%), meter is +3 kWh from the beginning when I started measuring and My Ford Mobile, and the car continue to say "Waiting to charge"! LOL
So I started checking on the car at 11:45am: It has used a total of 3 kWh in 4 hours 45 minutes (much slower than charging at the full Level 2 rate).
(When I started I was about 4 kWh down from a full charge with this being Sunday it was fully charged overnight and I took it for a short ~15 mile drive before monitoring the meter.)
Outside temp has been in the upper 20s for the duration and the car in the shade.

Given what I'm seeing I would speculate that to turn on the TMS the car has to also turn on the charger; given that its set to charge later it puts the charger into its "slowest" mode possible...

 

[dmen]

Interesting. Thanks for sharing! So if I'm reading your timeline right, in 25 F weather you used 3-4 kWh from meter to put 10% = ~2kWh into the battery, for essentially 50-67% charging efficiency.

Would it be possible to see how much more the meter records after the battery is fully charged? That is, how much it uses to keep the full battery cozy. And how much is used to complete a cold-weather go time? If the car starts humming an hour before go, and the cabin heater pulls 5+ kW, it probably adds up.

Of course my questions are really just wondering how much more electricity is being used to drive and maintain the FFE in winter. I guess the easiest way would be to read the battery soc at plugin, read the meter at plugin, and read the meter at morning departure.
KWh added / meter difference = observed charging efficiency, but I would think actual charging efficiency remains ~80% so
[Meter difference - (kWh added / 80%)] should reflect extra energy used to deal with winter.

 

[jmueller065]

Would it be possible to see how much more the meter records after the battery is fully charged? That is, how much it uses to keep the full battery cozy. And how much is used to complete a cold-weather go time? If the car starts humming an hour before go, and the cabin heater pulls 5+ kW, it probably adds up.

Typically my car is fully charged between 3am and 5am times I'm not likely to go outside and check the meter!

This week, however, with the holiday may afford an opportunity to check.

 

[jmueller065]

I took some readings/measurements last night:
http://jamiegeek.myevblog.com/2013/11/27/some-numbers-on-the-cold/

 

[WattsUp]

I took some readings/measurements last night:
http://jamiegeek.myevblog.com/2013/11/27/some-numbers-on-the-cold/

Your article mentions that charging efficiency is about 90%. According the EPA source you cite, the overall charging efficiency for an EV is determined by the both the charger and battery, the combination of which is actually only about 80% efficient (at converting energy "from the wall" into the energy "in the battery").

 

[jmueller065]

Your article mentions that charging efficiency is about 90%. According the EPA source you cite, the overall charging efficiency for an EV is determined by the both the charger and battery, the combination of which is actually only about 80% efficient (at converting energy "from the wall" into the energy "in the battery").

True but given that that # is just an estimate anyway it doesn't really affect the number too much anyway. If I use 80% then the calculation would be:
10 kWhr - 7.2 - (0.2*7.2) = 1.36 instead of 2 kWh.
But we really don't know what the FFE's charging efficiency is so its still a swag.

Ok updated the post...

Off to the dealer to pick up my car--got the SSN recall done today. I fear the dealer may have messed it up though--its taken all day and when they called they said it will be done in an hour or so because it was "taking time"?? WTF??

 

[davideos]

--its taken all day and when they called they said it will be done in an hour or so because it was "taking time"?? WTF??

My guess is that they just figured out how to do it and the procedure probably tells them that it will take an hour. So they probably called you in advance since it is the last day before a long weekend and they don't want to wait longer than they have to for you to come and pick it up...just my guess Maybe they will throw in a free oil change and multipoint inspection for your inconvenience! When I purchased my car, that's what the dealer gave to me....yes, I did give them a funny look.

All my updates took longer than estimated. I know when they did the sync update a few months ago, it took them all day to figure it out. I ended up having to pick it up the next day.

 

[jmueller065]

Picked it up and took it for a good 15 or so mile drive. It doesn't seem any worse for wear--glad they didn't brick it LOL.

I did ask them what took so long. The response was that they had to reprogram 4 modules and each module was taking 45 minutes each to program. And yet they never plugged it in--at least they didn't for the half dozen times I checked throughout the day.

Considering my dealer is right across the street from the plant I figured it wouldn't take long if they had to get someone from Ford to look at it! LOL

 

[jmueller065]

Power usage update: Before taking the car across town today I measured the power consumption for the precondition. Here are the conditions:

• Outside Temperature: 25F
  Battery 100% Full
  Precondition to 85F
  Slight layer of snow on the car, brushed off

For the above conditions it consumed a whopping 5kWh to complete the precondition.

 

[WattsUp]

For the above conditions it consumed a whopping 5kWh to complete the precondition.

55 cents?

 

[jmueller065]

For this precondition the cost was more like 90 cents because it was during the high-rate time of day (40 cents for the low rate time of day).

 

[EVA]

That's a great piece of information to show just how much power the heater uses. 5Kwh to go from 25 degrees to 85 - not that you would set your car to 85 while driving - that's a massive hit on range. New meaning to, keep the temperature as low as possible while driving.

 

[dmen]

Jmueller, thanks again for sharing your numbers.
The precondition use is what I kind of figured, seeing as the heater takes 5+ kW power while driving and it's running for over a half hour to get the car up to temp. I'm pleasantly surprised by the small amount of energy used to keep the car happy overnight. 1.5 kW or so over what, 12 hours?
On the other hand, that 1.5 together with the 5 from cabin preconditioning as well as the increase in energy use to drive in cold (you weren't using 7.2 kWh on your commute in September, I'm sure) means you are using about twice as much energy to commute with your FFE in cold vs warm temps.