Preconditioning Observations

[jadnashuanh]

As some of you may remember, I installed a volt/amp meter on the lines feeding my EVSE about a month ago.

It was warmer then, and I'd mentioned that preconditioning on a fully charged battery was using about 12A at 245vac. Well, it was colder this morning, and when I went to disconnect the cord, I noticed that it was cycling between about 12A and nearly 19A. So, since power=volts*amps, when it was warmer (but still needed heating), at 12A*245vac, it was using 2940Watts; 19A*245vac, it was drawing 4655Watts! Since it was cycling between those two figures (maybe a heating element turning on and off?), it was averaging nearly 3800W. So, since it can take awhile to get the cabin up to temp (and the batteries as well), if you aren't connected to the EVSE at the time, that can eat up a fairly significant portion of your power available. I was surprised that it was now bouncing off 19A (it could be higher, but the sample rate on the meter is only a couple of times/second).

FWIW, I normally run the climate control at 70-degrees F (about 19C). WHen I went down to use the car, it had been preconditioning for about 20-minutes.

So, from this observation, if you don't precondition while plugged in, it will suck a fair amount out of your battery while doing it, and if you have to do that several times during the day because things cool back down again in between trips, your range has to drop. Rounding some numbers, say you don't precondion and do it on the fly, so to speak, the car will use about 4Kw, say 1/2-hour getting things fully up to temp at each end of the trip. At around 4-miles/Kw, that's 16-miles off your total available range. More if you make more shorter trips and the car has to rewarm itself multiple times.

For those of you using the (in the USA, anyways) 12A, level 1 EVSE provided with the car...it may end up slowing the speed it can precondition since, at least on mine, the car is using more than what could be provided from the level one device (no worries, the car won't take more than it announces is available).

Even if you run your cabin temperature lower, the car still needs to use some power to condition the batteries, and you are likely to be using the wipers, lights, and maybe the rear defroster more in the winter than the summer...IOW, your typical load will be greater. It could certainly help if you parked in a heated garage! At least on the first half of the trip, the conditioning load would be significantly decreased.

We don't notice this as much with an ICE, since heating is an almost free by-product of the combustion engine. It only becomes more of a load if you use more electrical devices and the alternator needs to run harder/longer.

 

[acmik]

Maybe this 12A/19A difference refers to the battery resistive heating, which is, as far as I have seen, done only when connected to EVSE.

 

[FrancisJeffries]

At around 4-miles/Kw, that's 16-miles off your total available range.

...for two warm-ups.
That accords with my own experience recently. On a very frosty morning, I decided to start the preconditioning without plugging the charger in (the car was already fully charged). The interior temperature was set to 22C. After 10 minutes, the windscreen frost was water. At 30 minutes, the preconditioning had just turned itself off. All the windows were dry and the inside was as warm as toast . The range was showing as having dropped 8 miles (to 56 from 64).
15 minutes would have been plenty to make the car completely drivable without having to get a scraper out! :lol:

 

[jadnashuanh]

So, it sounds like my meter readings correspond well with others observations. Good to know. Most of my trips are only a few miles, so generally, I don't worry about it (only about 1500-miles in the last 5-months).

I think the bottom line is: precondition while on the EVSE whenever you can if you are worried about maximum range. This is mentioned by BMW in more than one place, and now the effects can be seen in the real world as well. Maybe they did their homework!

Personally, I think they intentionally overheat the cabin in the winter to help insure you can get the snow and ice off without much scraping, and to help that heat penetrate the cold-soaked interior. I find it really uncomfortable to set back the heat in my house when I'm going away for a few days, and even when the air temp is comfortable after returning...sitting on the couch or laying in bed, the cold just soaks into you before you can warm things up again.

 

[Sparky]

I don't have my car yet so when I read these threads I'm a little confused. Do you precondition the cabin air or the battery temp or both?

 

[mindmachine]

I don't have my car yet so when I read these threads I'm a little confused. Do you precondition the cabin air or the battery temp or both?

Both.

 

[Sparky]

Is this something I would consider if my car is garaged and never colder than about 45-50 degrees?

 

[mindmachine]

Is this something I would consider if my car is garaged and never colder than about 45-50 degrees?

Batteries like it warmer than 45 to 50 deg, so yes. Around 65 to 70 deg it probably isnot worth it, but in the heat of summer it again is worthwhile.

 

[Sparky]

Is this scheduled by an app or in the car?

 

[mindmachine]

Is this scheduled by an app or in the car?

BMW i Remote app will do it and/or there is a setting in the car too that works with delayed off peek charging.

 

[jadnashuanh]

Because I'm not on any regular schedule, I precondition from remote via either my phone or if home, possibly my tablet, both of which have the same app running and can monitor and control certain things on the car. The app is free and works on both iOS and Android devices. You wouldn't be able to do much with it (I don't think) until you know your VIN, and they've activated your link to the car. The app store has some screen shots so you can get an idea and you could download it, but again, I don't remember how much you can see until your account is setup after purchase of the vehicle. Look for the iRemote app, and make sure you get the proper country's version.

 

[RJSATLBA]

Is this scheduled by an app or in the car?

BMW i Remote app will do it and/or there is a setting in the car too that works with delayed off peek charging.

And there is also an option which is automatically presented when switchong off the car to set a 'Next departure time' over and above the three stored schedules.

 

[user 1096]

Thx for those pre-conditioning draw observations. I have been wondering how much the pre-conditioning eats up watts and it sounds like it goes full-tilt on the demand. I dislike doing it when I am only running about 2 miles and it is mild, but down in single-digits, I usually always try to do it (as long as the app is communicating).

Now, I'm going to guesstimate the efficiency loss of colder temps on the big battery. But as we all know, relying on the Guess-O-Meter is nearly hopeless considering how you LAST drove and what the temps were then vs now.....Oh, something to contemplate when there's nothing on Sirius, which seems to be fairly often.

 

[i3atl]

FYI, according to the information presented recently on the FB group, choosing the "Preconditioning" option from the Remote section of the app only conditions the cabin - not the battery. In order to condition the battery, you must schedule a departure time via the "Set timer" button in the app or in the car.

 

[stumbledotcom]

Here's is purely anecdotal observation about not preconditioning yesterday. I hadn't plugged in overnight so the car started cold. Ambient temp showed 14.5° C or 58° F. Charge was a bit more than 75% (three bars plus a sliver of the fourth) and a range estimate of 59 miles when I set off. Drove in Comfort with climate control and seat heater on. When I stopped after about 2.5 miles, the range estimate had actually gone up to 62 miles.

My amateur analysis: The relatively mild temperature meant the batteries reached their ideal operating range while I drove hence the range estimate going up despite the distance I traveled. It doesn't get cold enough here and I don't drive far enough in a single trip for preconditioning to matter. However I can extrapolate that it would make a worthwhile difference in a colder climate.

 

[AlexAtlantaEV]

I am hopefully going to have i Remote setup tomorrow when I get BMW assist going. So from what I gather, preconditioning is just for the cabin and the departure timer is for the battery. Now that we are in winter, I feel I should really take advantage of this for range purposes. I also have the BMW wallbox which talks about preconditioning a little bit in its manual (supposedly drawing power from it while it is plugged in from what I read in it). What sort of departure time should I set if I want any used energy to be mostly replenished? (should I set it prior to my actual departure time a bit?). After a full charge earlier today, it was nice seeing 115 miles on the dash, but of course that dropped as I went about my day and the temps dropped drastically.

 

[mindmachine]

I am hopefully going to have i Remote setup tomorrow when I get BMW assist going. So from what I gather, preconditioning is just for the cabin and the departure timer is for the battery. Now that we are in winter, I feel I should really take advantage of this for range purposes. I also have the BMW wallbox which talks about preconditioning a little bit in its manual (supposedly drawing power from it while it is plugged in from what I read in it). What sort of departure time should I set if I want any used energy to be mostly replenished? (should I set it prior to my actual departure time a bit?). After a full charge earlier today, it was nice seeing 115 miles on the dash, but of course that dropped as I went about my day and the temps dropped drastically.

Departure time is what it is, if you want to leave at 9am set it to 9am departure time 10 am set it to 10 am, simple as that. Thats when you want to depart,(ie departure time...).

 

[jadnashuanh]

The car will adjust when it starts preconditioning based on various conditions, some we may never know. But, as said, you want to leave at a certain time, set it to that. If you've got a low-cost charging window, it might start outside of that window to meet your request.

 

[srswans]

The first time I tried preconditioning on the supplied 110V cord, the battery was down 1/2 a quarter bar when I got in the car. I had enabled preconditioning from the Remote app. The battery was at 100%, according to Remote, before I enabled preconditioning.

Does preconditioning not work on 110V with the supplied cord?

 

[jadnashuanh]

As I said, on my level 2 EVSE, I've seen it draw nearly 20A when I asked it to precondition. Since the level 1 EVSE is limited to 12A, and if the car really wants all of that 20A I saw, some of it will have to come from the batteries, and it appears that yes, it can draw down the batteries...if it tried to do the preconditioning at a slower rate, it might let it stay at 100%, but it might end up never getting there.

IF my premise is correct, preconditioning with the level 1 EVSE attached would still save some, otherwise, you'd be drawing that entire 20A from the batteries alone, verses pulling some of it from the EVSE.

Anyone know for sure?