Close Call (4% charge remaining) and Lesson Learned

[Woland]

The other day I had a business trip in Vancouver, BC, and I drove up in my P85D from Woodinville, WA (near Seattle). I've done this trip a few times before so I didn't think much about it or have any real range anxiety. What I do is charge to full overnight, drive up to Vancouver in the morning, meet with a business partner for a few hours and then hit the Burlington, WA Super Charger on the way back home.

Normally I get back to the Burlington SC with about 12-16% charge, but this time, I arrived with only 4% and quite a bit of anxiety. What was different this time is that the weather was warmer than previous trips (54 F when I left home, and around 71 F when I left Vancouver). So while you'd normally think that's an ideal temperature for max range, I learned a new lesson here that I thought I'd share.

Upon arriving in Vancouver, I parked in the partner's parking lot and checked the expected charge remaining to the Burlington SC. The car thought I'd get there with 16%. "Cool," I thought, "I should be good." I met with the partner for about 4.5 hours and then opened the Tesla app on my phone on my way out of the building. 112 degrees F in my car!

Upon entering the car I checked the estimated charge remaining to get to the SC. "Drive below 55 to reach your destination!" Doh!

What happened, as you can imagine, was that the battery cooler had turned on during my meetings and had drained the battery in the process. OK, lesson learned. Should I try to make it to the SC? I got on the highway and the estimate soon changed to 5%. I drove around 60 MPH for several miles and managed to get the estimate up to 6%. Most of the way to the SC it hovered around 5 or 6%. After a couple small hills, it hit 4% and remained there until I pulled into the SC, breathed a sigh of relief and charged up for the last leg home. Yes, I could have hit a non-SC to get a splash charge, but none of them were on my direct path back to the SC, and they all looked a bit dubious on PlugShare.

So, the moral of this story is "don't park your car in direct sunlight (unless it's very cold outside - even 70 degree weather in direct sunlight can equal 100+ degrees inside the car) if you're pushing 20% or less remaining charge back to your next charger." The car will do what it needs to keep the battery healthy and happy, potentially at the "expense" of the driver's nerves.

 

[FlasherZ]

Are you sure it was the battery cooler? Did anything give you an indication to that?

My experience has been that the active cooling target is much higher than what can be accomplished with 70 degree ambient temp while not charging. The battery has a lot of thermal mass (unlike the air inside your car), and so it's not very likely that your battery reached that level to trigger the active cooling of the pack.

There is a list of "other stuff", though, that I've watched out for... the "smart" preconditioning sometimes kicks in, and it isn't very "smart". It will run several miles off your battery as it cools your car. If new software is being pushed to your car, it tends to stay awake and vampire drain increases (although usually this is only about 5-10 miles over a few hours).

Did you look at the wind profile that day? That's a big, big factor here in the midwest.

 

[Woland]

The battery fan was on when I got back to my car, so yes, I'm pretty sure that's what it was.

I disabled the "smart" preconditioning thing several months ago. No new update was installed. There was pretty much zero wind, and even then, when I parked the car the estimate was 16%, and when I returned it stated "Drive below 55..." which is an indication of less than 4% I assume. As I drove, it went up and down, but never below "Drive below 55..." and never above 6%.

 

[apacheguy]

The battery fan was on? Hmm. You mean the side lovers had been actuated and a load fan noise was audible? Did you pre condition? Even at 112 F inside the car, the battery would be much less. Passive cool is 30 C and active cool is 52 C. I really doubt the battery cooler was responsible.

 

[Woland]

The battery fan was on? Hmm. You mean the side lovers had been actuated and a load fan noise was audible? Did you pre condition? Even at 112 F inside the car, the battery would be much less. Passive cool is 30 C and active cool is 52 C. I really doubt the battery cooler was responsible.

Yes, the fan was on and audible as I approached the car. I had woken up the car with the app, but had not set any climate changes. As I said before, I did not pre-condition.

If the cooler wasn't responsible, what do you attribute the fan sound, or the depletion of charge, to?

 

[apacheguy]

Well, honestly I have no idea why the battery chiller would have activated with an ambient temp of 71 F on a resting car. Sure, the interior is much warmer, but the air has a lower heat capacity. All I'm saying is that something doesn't smell right. In over 3 years of ownership I've never observed the battery being cooled on a 70 F day. If this happens to you frequently then I suggest you have service pull the logs because it is not normal beahvior.

 

[Woland]

I understand your point, but I've heard the battery fan before at Super Chargers, and my recollection from the other day was that the fan sound was the same. It sounds different than if the car interior is being warmed or cooled from the app. I don't recall any other such incidents.

Thanks.

 

[pdxrajiv]

Is it possible that you were parked on top of something that might account for the difference in the temp of the battery vs the ambient temperature - like being parked on top of a (stree-level) heat vent? One normally does not think about such things, but maybe we should.

 

[S4WRXTTCS]

Was range mode on or off?

 

[Tdriver]

You say you woke up the car with the app. Could you having unknowingly or accidently turned the AC on at that time? All part of the learning curve as I learned......
4% is certainly low.........I ran at 0% for 20 miles on a mild downgrade.........that was what you would call anxiety.

 

[Woland]

I'm pretty sure I wasn't parked on a vent.

Range mode was on.

I specifically did not turn on AC / climate from the app, as I wanted to conserve charge.

Also, as an additional anecdotal bit of info, when I pulled in and parked in my garage last night I heard the battery fan come on after I put the car in park. It went off as soon as I got out and closed the car door. It was about 80 degrees F at that point. So my car at least thinks it needs to cool the battery in only moderate heat.

 

[FlasherZ]

Also, as an additional anecdotal bit of info, when I pulled in and parked in my garage last night I heard the battery fan come on after I put the car in park. It went off as soon as I got out and closed the car door. It was about 80 degrees F at that point. So my car at least thinks it needs to cool the battery in only moderate heat.

If it turned off when you closed the door, it's likely the climate control fan. I hear that one as well, and when I close the door it goes off. If the battery is in active cooling mode, it won't shut off until the temperature condition is satisfied -- and as others have noted, very rarely does Model S ever use the active cooling.

That said, all of this should be in the logs, you may want to call the service center and give them the date and time when this occured. They'll know whether it's battery pack active cooling or the climate control.

 

[Woland]

If it turned off when you closed the door, it's likely the climate control fan. I hear that one as well, and when I close the door it goes off. If the battery is in active cooling mode, it won't shut off until the temperature condition is satisfied -- and as others have noted, very rarely does Model S ever use the active cooling.

That said, all of this should be in the logs, you may want to call the service center and give them the date and time when this occured. They'll know whether it's battery pack active cooling or the climate control.

If it was the climate control fan last night why did it come on only after I put the car in park, and why would it be much louder than the climate fan noise I've heard before? I wasn't using climate control (or at least not above fan speed 1) during the drive home last night; I had the windows open and that's how I heard the loud fan noise come on after putting it in park in the garage.

But even if the fan noise I heard in Vancouver was climate and not battery, how would you explain the loss of more than 10% charge parked for four hours? Even if, when I opened the app as I approached the car, the AC came on, that would have been less than 10 seconds of AC. And if the AC came on earlier, why was the interior so hot? The temp was set at 73 when I got out of and into the car.

I'll definitely let my Tesla service center know about all this because it seems at least I have some weird behavior.

Thanks!

 

[FlasherZ]

I can't answer those questions. It could very well be that you have a bad sensor for active cooling, or something similar. I'm reacting based upon my experience and your description, but I've long known how <sarcasm> "wonderful" </sarcasm> technology can treat us.

By any chance do you have the scroll wheel on the right set to adjust fan speed? I've accidentally ramped up the fan speed to 11 when I've put the car in park before by brushing my thumb against it (my right scroll wheel is set to adjust fan speed).

As for the range loss, that I can't explain without having more information. You mentioned that "intelligent" pre-conditioning is turned off, that's the first place I'd go looking. With a fan speed on high and on a hot day in the sun, the car could lose a good amount of energy running A/C for that long (the compressor alone at full speed takes over 3 kW) - but you noted that the car showed over 100 degrees inside, so it likely wasn't that.

Either way, the service center should be able to help you -- you should give them a time +/- 30 minutes or so when that occurred, and they should be able to pull the logs to see whether the active cooling turned on or not. Good luck!

 

[BrokerDon]

I had a similar "range anxiety" drive going from Orange County, CA to Las Vegas when we ran into strong headwinds. I noticed my estimated range at my destimatoin (Primm, NV) start to decrease fairly rapidly from 19% when we left the Barstow CA Supercharger. I decreased my speed from 80 mph to 70 mph and put the air suspension to Low until I found a nice "air dam" to follow... a Mercedes Sprinter van cruising at 80+ mph. I tucked in behind him, and turned on Range Mode AND set AutoPilot at 85 mph with TACC distance = 1 to stay inside his massive "draft". Almost immediately our estimated range to our destination started climbing up and we arrived at the Primm NV Supercharger with 25% range while averaging 80+ mph... MUCH better than slowing down to 60 mph just to maintain our estimated range.

TACC was amazing mirroring the Sprinter van's speed perfectly... and Autopilot made the drive the easiest drive we've EVER done to Las Vegas.

 

[Eugene Ash]

a nice "air dam" to follow... a Mercedes Sprinter van cruising at 80+ mph. I tucked in behind him, and turned on Range Mode AND set AutoPilot at 85 mph with TACC distance = 1 to stay inside his massive "draft".

I used same approach on iMiev (16kw battery) trips from Seattle to Portland, and glad to be able to try it soon with TACC... this is an awesome strategy and use of TACC!

 

[Todd Burch]

I've parked the car in 100+ degree weather in the middle of summer, on a calm sunny day, over blacktop, for a full workday and still not heard any active cooling. As others said, the active cooling target (battery cooler kicks in) is 130+ deg F. If your cabin (greenhouse) was only 112 degF (which really isn't that hot), I'd be shocked if your battery was actively cooling. The greenhouse of the cabin would be much hotter than your pack, which is technically in the shade under your car and has a lot of thermal mass.

My bet is that somehow the heater or air conditioner somehow got turned on. I know you don't think it did, but that seems the most likely possibility. Is it possible that you accidentally bumped the setting and turned smart preconditioning back on? Or perhaps some update reset it back on?

 

[Lanber]

You get more thick skin with this with experience. 4% is plenty, that`s like 16km (10 miles) real world range.

The end of drive % predictor is pretty good.
Had a roadtrip to pick up a dog in easter, was at SC Uddevalla and had a long way to next SC (268km), when I had a some 320km range I set sail and immediatly car started telling me to keep speed low to reach destiantion.
This I did, but kept it 10km/h above recommended speed all the way and monitored it keenly, arrived with 1%.

No sweat whatsoever, I knew all the way I could get there if I slowed down more. On such a long trip you can save a lot of range by dropping speed.

 

[Woland]

My bet is that somehow the heater or air conditioner somehow got turned on. I know you don't think it did, but that seems the most likely possibility. Is it possible that you accidentally bumped the setting and turned smart preconditioning back on? Or perhaps some update reset it back on?

I suppose it's possible, but Smart Preconditioning was, and still is disabled. If the AC was turned on, I didn't turn it on. My cell phone was in my backpack the entire meeting. The app was not open when I left the meeting, and again, the car was 112 degrees when I returned to it, so if AC was turned on, it should have cooled the interior. If AC turned on earlier in the day, burned through some battery charge, and then shut off, that's quite bizarre (arguably even more bizarre than the battery cooler coming on).

Thanks for all the ideas and advice everyone!

 

[LetsGoFast]

My experience is closer to Woland's than that of many of you. I frequently go out to my car in the parking lot at the end of the day and find a puddle underneath from the A/C or have employees report to me that the car is running. No "smart" preconditioning and no manual activation of the A/C. It does it inside my garage as well, but it needs to be more like 85 or so for that to happen.