Subzero experience - lessons learnt

[BenT]

Last night I ran out of battery power for the first time. I was quite surprised. I had an 11km trip and 20 km of range. I have run the car fine on a few occasions and not had a problem so I wasnt too concerned. I thought i would just reduce my speed and i should be fine. It was about 7 degrees C and the car had been sitting for a few hours so i assume the cold battery was a factor. Almost from the start I had markedly reduced power and speed. This should have been a warning to abandon trip but given that the last 1/2 of the trip was steep downhill and thus usually a positive charge I was still confident i would be ok. As I drove the range was falling at a precipitous rate. In the end it dropped from 4 km to 1 km and then 0km over around 500 m and the car announced it was shutting down so I pulled over about 200m short of the downhill stretch on a freeway. I was surprised that all the lights and the screens in the car all shut down pretty much straight away. I thought they would be running off the 12V. Thankfully the hazard lights still worked but the audible click click had stopped. Even the Tesla app connection went off so there was no way to engage tow mode or pop the frunk from the screen or app. Luckily some friends were nearby so picked up the family while I waited for assistance. When the family got out of the car the doors opened and the screens came back on for a short time so I took advantage to pop the front trunk and put the car in tow mode. A word of warning. When you put the car in tow mode it takes the handbrake off so it would be good to carry some wooden blocks in the car to chock the wheels. I was alone by then and the screens went blank again almost as soon as i had put it in tow mode so i was stuck in the car with my foot on the brake as I was on an uphill incline so if I took my foot off the brake the car was going to roll back down the hill so i was stuck waiting for assistance with a foot firmly on the brake hoping it wasnt going to be too long. The next learning point is that Telsa roadside assistance do not cover towing in the event of a flat battery. Thankfully I maintain my RAA cover and they do cover towing up to 10km which was more than enough to get me to my destination. The RAA phone call response was also a lot quicker than Tesla, however I did have to wait a fair while for the tow truck which was a little disconcerting at midnight in 7 degree temps with my foot on the brake. Finally the flat bed tow came and i was glad i had engaged tow mode before the whole system shut down because this made it a lot easier. The tow driver took me the last 5 km home and was able to unload the car and I chocked the wheels with some bricks on the road outside the house. Where I could run an extension cord out to connect to the UMC. Thankfully the charge port opened in response to the charger cable but the cable wouldn’t insert. There is a small plastic tag inside the charge port which locks the charger cable in and this was fixed in the lock position so the charger cable
couldn’t be inserted. I managed to fick it up with a credit card corner and squeeze the charger in. With 10 amp power very little happened for about 30 minutes. Eventually the car came to life and the screens and app connection came back on. I left it for another 30 minutes and it still said 0km but at this point I was confident enough to unplug the UMC and move the car into the garage and onto HPWC.
So the lessons learnt. 1. A cold battery handles very differently to a warm battery. 2. If you get significant power reduction this is the time to find a power outlet, even just a household 10 amp. 3. You have very little time to use the car functions once it does run out of power. Carry chocks. Chock the wheels. Engage tow mode and pop the trunk ASAP. 4. Dont rely on Tesla roadside assistance for a tow. Your local automobile club membership is a better bet. 5. When there is no power it is difficult to plug in the charger. Have some tools on hand to help with this. A thin plastic slightly flexible lever is best. 6 Even once you do connect to power it will take some time to reactivate the vehicle.

 

[mmui90]

Um... other than the unformatted wall of text, I only have one additional comment.

Isn't it highly irresponsible of someone to let their car get down to 20km of range with family on board in winter temperatures? Sorry you had to go through that, but I hope you never do that again!

 

[sczsimos]

Um... other than the unformatted wall of text, I only have one additional comment.

Isn't it highly irresponsible of someone to let their car get down to 20km of range with family on board in winter temperatures? Sorry you had to go through that, but I hope you never do that again!

Um, I thought it was a very useful post worthy of more than cheap derision.

 

[PJF000]

The car would have warned of the battery condition and to charge asap before starting off. Probably continuously as it faded out.

 

[Cosmacelf]

Thanks for the info/story. Helpful!

Btw, I second being cautious in cold temps. One night in around 0 C temps, I arrived at my destination with about 11km of charge. Restaurant was about 1km away, so we drove there and parked. About an hour later, after just sitting in the cold, the car range was down to 4km. I barely made it back to where I could charge.

 

[Shock-On-T]

Very useful warning, thanks for that. Especially useful for those planning a ski trip this year.
I had a very similar experience visiting family in Tasmania. Was relying on a normal power point and UMC, and they night we arrived the car was up to about 40km range when we decided to go into Hobart for dinner. 10km each way, starting high up a mountain.
Got to Hobart with 33km range, with a 10km uphill return trip awaiting. About 5C outside temp.
After dinner car was stone cold, and going up hill was dropping 3km every 1km travelled, sometimes more. Arrived hope with clenched sphincters all round and just a few km range remaining.
Gotta watch that cold!

 

[Shock-On-T]

Um... other than the unformatted wall of text, I only have one additional comment.

Isn't it highly irresponsible of someone to let their car get down to 20km of range with family on board in winter temperatures? Sorry you had to go through that, but I hope you never do that again!

Easy mistake to make, thinking you can go 11km with 20km range. You don't know what was happening before this, might have had no chance to charge and made the reasonable judgement that he could make it home with 20km juice.
I've been caught out like that myself, and I'm an absolute legend.

 

[ICUDoc]

Thanks for the reminder, OP. Cold and low battery is a bad combination.

 

[Tam]

...an 11km trip and 20 km of range...

Thanks for sharing your experience.

1) 12V battery:
I wonder how long the car was unplugged in such a low State of Charge?

With an ICE, your 12V battery is still charged as long as there's still a drop of gasoline for the engine to run (which runs the alternator for 12V charge).

Not so with your Tesla: In a low state of charge, the main battery would stop supplying energy to certain components such as importantly, your 12V battery! Your wheels can still roll around but your 12V battery might be starved for a charge.

2) Since 2012, many owners have reported that in cold weather, the battery heater might automatically want to warm up for its own use and drop your range suddenly.

 

[Puddles]

I generally consider the remaining estimate to be very accurate, and plan accordingly. I can easily see this happening.

 

[BenT]

Hindsight is 20/20

Isn't it highly irresponsible of someone to let their car get down to 20km of range with family on board in winter temperatures? Sorry you had to go through that, but I hope you never do that again!

 

[paulp]

Thanks for the detailed description BenT. I dont plan on being in that circumstance, but now if I am I at least know what to do and expect.

 

[miimura]

When in this situation where the car has shut down and you don't know how long the tow truck will take to arrive, you should open the frunk with the remaining power and don't put it in tow mode. When the tow truck arrives, connect the tow truck's 12V jump leads to the 12V posts. This will allow the car to wake up and power the computers to open the doors and turn on the screens. When the tow operator is ready, then put it in tow mode. Opening the frunk allows you to avoid removing the nosecone or using the emergency release behind the bumper cover on more recent cars. If you don't know where the 12V posts are or how to get into the funk when the car has lost power, look it up in the manual either online or on the car's screen, preferably before you need it.

 

[ecarfan]

When in this situation where the car has shut down and you don't know how long the tow truck will take to arrive, you should open the frunk with the remaining power and don't put it in tow mode. When the tow truck arrives, connect the tow truck's 12V jump leads to the 12V posts. This will allow the car to wake up and power the computers to open the doors and turn on the screens. When the tow operator is ready, then put it in tow mode. Opening the frunk allows you to avoid removing the nosecone or using the emergency release behind the bumper cover on more recent cars.

Excellent advice.

@BenT sorry to hear about your experience and thanks for your detailed post. Over the years on TMC there have been many similar threads. I would never try to drive any of my Teslas with less than 30km of range displayed, and colder weather only makes it even more risky.

Your post mentioned the temp was 7C so I am unclear why your thread title says “subzero”. I am suggesting that the forum moderator edit the thread title for clarity. Thanks.

 

[BenT]

Excellent advice.

Your post mentioned the temp was 7C so I am unclear why your thread title says “subzero”. I am suggesting that the forum moderator edit the thread title for clarity. Thanks.

The subzero refers to where my battery charge ended up as much as the fact that it was cold. A little bit of poetic license. I think the context is there in the text. No need for moderator censorship i think.

 

[Shock-On-T]

@ecarfan, @BenT Don't forget that temperature is just an average of the individual temperatures of all the molecules in a given system, so even with the thermometer reading 7C there would be some molecules in the air and the batteries that were indeed sub-zero.

 

[miimura]

@ecarfan, @BenT Don't forget that temperature is just an average of the individual temperatures of all the molecules in a given system, so even with the thermometer reading 7C there would be some molecules in the air and the batteries that were indeed sub-zero.

More importantly, if the car cold soaked overnight at -5C and you drove it later when the ambient air had warmed to 7C, the pack internals could still be below freezing. You have no control over what the battery heater does, so be prepared for it to "unexpectedly" consume range. Also, remember that when the battery is truly cold, it will take "forever" for the power to ramp up on a Supercharger. People have shown that the car will sit there not taking in any more power than what the accessories and battery heater are taking for 15-30 minutes, not adding any energy to the battery pack itself. Only when the car is satisfied that the battery is warm enough will it start adding energy to the main battery pack. This is one of the main reasons that destination charging is really important when on holiday in the mountains.

It is also significant that the Model 3 does not have a dedicated resistive heater for the battery pack like the S and X do. It only uses waste heat from the drive inverter and motor to heat the battery pack. However, Tesla have implemented a heating mode that passes significant power through the inverter and motor without generating torque to create heat for the purpose of circulating warmed coolant into the battery to heat it.

 

[LDCRS]

Informative and hopefully we can all learn from your lessons.

I personally would never really want to cut it that close but understand sometimes we get stuck in all sorts of situations but at least this gives us some sort of perspective of what our 'expectations' of the range should be at colder temps. I guess it's pretty hard to understand it unless you experience it first hand.

 

[Blue heaven]

Up until the past two weeks I've only noted one Tesla in Australia running out of charge, I'm sure there have been others not reported, recently there have been a number of experienced Tesla owners having cars shutting down with range still showing, some of those were in warmer conditions than @BenT . As well as a cold pack that depletes faster it's also lack of calibration, but it also could be a result of recent software updates.
Maybe it's time to consider 20kms remaining as the new zero.

 

[Shock-On-T]

Up until the past two weeks I've only noted one Tesla in Australia running out of charge, I'm sure there have been others not reported, recently there have been a number of experienced Tesla owners having cars shutting down with range still showing, some of those were in warmer conditions than @BenT . As well as a cold pack that depletes faster it's also lack of calibration, but it also could be a result of recent software updates.
Maybe it's time to consider 20kms remaining as the new zero.

When I first got my car 3 years ago, one of the staff at Tesla told me about someone running out coming back from Canberra to Goulburn. Not sure if that’s the same one you heard about.
I’ve done a few hair-raising trips in my 108,000kms, the scariest being a night trip from Port Macquarie to Armidale in a thunderstorm with howling rain and headwinds, climbing all the way. Arrived at motel with single digit kms left.