Slapped by Winter’s Cold

[iCJ]

This is my first winter with my 2017 i3 BEV. I knew going in the cold winter would zap a bit of efficiency/range, but boy does it.

I bimmercode’d mine to always boot up in EcoPro. In perfect conditions no hvac I easily get high 6’s kWh per mile. Once the temps drop below 33f I am getting 3.0 kWh per mile. No highway driving, 6 days a week my beloved i3 doesn’t go above 40mph, just city stop and go traffic with lights every 10 feet. I usually use the EcoPro hvac setting but under 40f I like my cabin toasty so turn that off. Not really interested in hypermiling I just want toasty warmth. i3’s heated seats ain’t no joke, setting 3 seriously could fry an egg and some bacon, I love that.

My daily drive is usually 20 to 35 miles so not an issue, also wife’s car is an ICE. In weather above 40 fahrenheit I usually charge every 3rd or 4th day, now in this weather I plug it in every night and set precondition. Sitting 8 hours uncovered in my job’s parking lot steals two bars of max power.

What is your folk’s experience of efficiency in the cold?

 

[alohart]

I bimmercode’d mine to always boot up in EcoPro. In perfect conditions no hvac I easily get high 6’s kWh per mile.

I think you meant to write "6 miles per kWh". Otherwise, with ~29 kWh of usable energy in your battery pack, you'd be able to drive less that 5 miles with a fully-charged battery pack.

I usually use the EcoPro hvac setting but under 40f I like my cabin toasty so turn that off. Not really interested in hypermiling I just want toasty warmth.

Fortunately, you can have your Eco Pro cake and eat your Comfort warmth, too. There's a setting in iDrive that allows one to select full climate control power in Eco Pro yet keep the less sensitive Eco Pro power pedal which could be safer on icy roads.

 

[3pete]

I've been tracking various things about my car for the past 4 years and living in the midwest means I'm "lucky enough" to have data corresponding to a wide range of temperatures.

This is a sample size of one car, so that should be taken into account but I think the themes are probably relevant to others as well.

FWIW, my car is 2014, 60ah battery with typical batt kapa max readings around 14kWh.

Total Range vs. Outdoor Temperature (left) and Trip Efficiency vs. Temp (right)

Unsurprisingly, they look similar as cold saps range due to worse efficiency.
Also unsurprisingly, efficiency and range start dropping again above 70F since my Climate Control is basically always set to 68-72.

Climate Control Cost vs. Outdoor Temp:
Left graph shows the actual reading on the eDrive setting of how many miles Climate Control is taking away from the total remaining range of the car.
The right graph shows this with an adjustment for how much % of battery is left. My thinking is that a full battery showing 10 miles of "CC Cost" means temperature is impacting the range by the same amount as 5 miles of "CC Cost" for a battery that is 50% charged. This may or may not be an accurate assumption, but the resulting graph isn't insanely out of line with the first one.

Again, "climate control cost" is smallest around 70F which makes sense.
Interestingly, the slope on the hot side seems steeper which may be:

• an illusion

• because I personally am more cold tolerant than heat tolerant

• because BMW is aware the battery is more cold tolerant than heat tolerant for long-term performance and lifespan

Lastly, I tried to show the total range of the car broken out by the car's estimated range with climate control ON, and the "climate control cost" broken out separately. To baseline these to a full battery, I divided each by the % charge. (So at 50% charge if the GOM says 25 miles of range and 5 miles of "CC Cost" I'm saying that's 50 mile range + 10 mile "CC Cost". Again, maybe not exactly accurate, but seems close.)

Here the light blue is the car's range and dark blue is the amount that should jump if I turned off CC. The whole bar would be the "total range on a full battery with CC off".

What's interesting here is that the "total range" seems to drop in the cold as well, even after adjusting for the climate control cost. It looks like it may be happening on the hot side of 70F as well, but not nearly as much.

 

[iCJ]

Thank you AlohArt. Must have been the spiked eggnog, I did mean to type high 6's miles per kWh. Thank you for the tip also. I do uncheck the climate in eco pro settings for climate, I did that in the most humid week in the summer too.

I use "comfort" driving mode as "sport" mode. So far Eco drive mode in the snow is almost perfect, do wish we could reduce regen a bit when its slushy out. I just got to be bit more mindful of pedal regulation.

 

[iCJ]

3Pete thank you so much for posting that data. this shows a lot!!!
Looks like we may be in the same line of work (analytics). Funny how we end up using it in stuff in our normal lives. I have scatter graph's for my AeroPress recipes and my espresso, plus a bunch of data for my weak sauce golf game.

Quick question, does your 2014 have the heat pump? If it does I would have assumed a steeper drop around the temp where it can't keep up. It looks very linear.

On the hot side it does show a drop, which I do wonder like you said may be due to your comfort level and due to you being in the midwest like me, means humidity levels higher than the rest of the year. Which as I age my bod'y's performance drops as humidity increases, so I do pump the AC more than I used to (just windows open). Also I would guess on the hot side because when we use the battery to drive heat is the by product and the car needs to cool it more than as in the cold just using the car will heat the thermal battery mass and not as much energy is needed to keep the battery in operation range. I think this is seen by those folks who have a Nissan Leaf and have a harder time cooling the battery so they don't get reduced charging speeds, yet in the cold to heat the battery they just drive fast to get the battery to temp.

I will probably spend the next hour looking over your graphs, as I enjoy geeking out on that stuff.

 

[3pete]

Quick question, does your 2014 have the heat pump? If it does I would have assumed a steeper drop around the temp where it can't keep up. It looks very linear.

It does, and I was expecting the same but I don't know what temp the i3's heat pump actually loses its effectiveness. Glancing around, it seems like it might be in the low 20s which is right about the bottom end of where I have a good amount of observations. Probably if I lived somewhere even colder (or went on more trips when there's a bomb cyclone/ polar vortex) we'd be more likely to see it in my data.

 

[iCJ]

I just saw on the YouTubes a guy testing in -20F a Tesla m3 with a heat pump against Tesla m3 without a heat pump to see which one would take the cabin temp from 0F to 75f first. The heat pump won by a big margin.

 

[SSi3]

...now in this weather I plug it in every night and set precondition.

But are you setting a departure time to go along with the preconditioning? If not then you're only heating the cabin and not the battery, which is why you're seeing grey bars and decreased efficiency after it sits for 8hrs and cold soaks the pack.

https://insideevs.com/news/325863/bmw-i3-how-preconditioning-works/

 

[iCJ]

Yes i am, Monday-Friday set departure time. At work I don’t have a charging option unfortunately and can only preheat the cabin from the app.

Now that the temps went to mid 40f efficiency jumped by almost double in my style of driving. Now I need to figure out coding the key fob for the frunk to keep the window scraper brush in there instead of the back hatch

 

[alohart]

Now I need to figure out coding the key fob for the frunk to keep the window scraper brush in there instead of the back hatch

On our 2019 U.S. i3, the following worked for me:

BDC (Body Domain Controller)
Change behavior of long press of key fob button 3
30D0->RC_DEFAULT_IDG_3RD_BUTTON_LONG werte: 05 (open frunk)

 

[iCJ]

Thank you so much for that! I will try and code that this weekend.

Was digging to find a BimmerCode to show the key fob menu in iDrive for buttons 3 and 4. Yours is easier.

 

[alohart]

Was digging to find a BimmerCode to show the key fob menu in iDrive for buttons 3 and 4. Yours is easier.

In the Head Unit module, try this in expert mode:

Add remote buttons 3 and 4 menu to iDrive (button 3 can open frunk)
3000-> KEY_CONF_*: set all to active
3000-> KEY_CONF_TAILGATE_SMALL_NAME: set to frontgate (03)

 

[iCJ]

Dude, thank you for this!!!

If there is ever an i3 meet up I owe you a few drinks and a lunch. I never use the trunk button on the Fob so the frunk will be great to have. I love the button 4 preconditioning as if I left my phone in the bedroom I can key fob warm my i3 from the back of the house.

Update on efficiency;
When it warmed to 40's-50F got back up to 4-5 mile per kWh. Now back to 20-30f I dropped to 2.9-3.3 miles per kWh. Seems like the threshold for my preference and driving style is the below 40f efficiency drops a bunch.

What about everyone else?