Charging After Power Failure

[M3xtr]

Hi Teslapeeps,

So I've done some searching and couldn't find the answer...

I have a 150km/day commute and in -10C weather I basically need to charge every night. I normally start charging at midnight because at that time Ontario's grid is one of the lowest carbon grids in the world. What I was wondering is if the power goes off at 1:00am, (when I am dreaming of driving the best car in the world!) and interrupts the charging, will the charging start again when the power goes on? I just want to avoid getting in the car in the morning with not enough range for the day.

Thanks! Paul

 

[Jetstreamsky]

Not experienced that yet, but it should restart as you will have set your charge level to what you want and if it’s plugged in and power is available it will charge until it reaches your set level.

 

[M3xtr]

Not experienced that yet, but it should restart as you will have set your charge level to what you want and if it’s plugged in and power is available it will charge until it reaches your set level.

I suspect you're right but if I think through the logic of the "scheduled charging" option I am not so sure. If the power comes on at 2:00am then I would have thought that the car would look at the time and see that it's not the time I programmed it to start changing and it would just simply wait. Now of course if somehow the car or some Tesla server knew that it was charging and that the charging was interrupted before it was finished then maybe it's programmed to start up as soon as the power is restored?

 

[Jetstreamsky]

All depends on how it’s coded I guess, if it’s a only trigger to start, then it may not recover when power becomes available again, but if it’s coded as start charging after the set time then all is good. I would hope it’s the latter as that is more of a fail safe design.

You could test it by setting up a charge session and after a few minutes cycle the breaker for your charger to see what happens.

 

[Futuresystem]

All depends on how it’s coded I guess, if it’s a only trigger to start, then it may not recover when power becomes available again, but if it’s coded as start charging after the set time then all is good. I would hope it’s the latter as that is more of a fail safe design.

You could test it by setting up a charge session and after a few minutes cycle the breaker for your charger to see what happens.

That’s what I’d do!

 

[brkaus]

That’s what I’d do!

Let us know!

I do believe I’ve seen a start window, but never studied it. If I have it set to start charging at 10 pm and plug in at 10:30 pm I think it starts right away.

 

[Magnets!]

The charger will restart after the power failure when power resumes and it is even smart enough to start randomly over a 3 minute period so that every Tesla charger in your neighborhood going on at once doesn't overload your local transformer.

Edit: this applies to the Tesla wall connector, not sure about the MCU

 

[Rocky_H]

1. Yes, randomized restart after a power loss. I think this may be mentioned in the manual.
2. Regarding the charging time, the manual does specifically talk about this, where there is a 6 hour window after your scheduled start time, so if you get home extra late and it's after your scheduled time, it will go ahead and start charging when you plug it in.

 

[M3xtr]

Thanks for the info guys! It sounds like some of you are pretty sure so that's good - will save me having to go do a test! Thanks again!

 

[ogio855]

Sorry to bring an old thread up, but I can confirm that the MCU will NOT restart charging after a power failure. My wife has a 200-280km commute/day and we have scheduled charging set to hit 90-100% about 30 minutes before she leaves to help not keep it at a high SOC for a long time.
Yesterday we had a power failure at 5:14 am for 55 seconds, car did not resume charging afterwards.
We tested it that evening by tripping the breaker during charging for 1 minute, car will not resume if it is on scheduled charging. Obviously no issue if scheduled charging is turned off.
Just realized we didn't try unplugging the car properly partway through a charge and then re connecting it, but I'll try that tonight!

Can anyone confirm that the Wall Charger definitely doesn't have these issues? No manual references, someone who's actually done it. I just cant see how the wall connector can override the cars computer to ignore the start time.

We were contemplating a second mobile cord to leave in the car, but if the actual wall charger is smarter it might be worth the extra $280 for peace of mind.

 

[Rocky_H]

Can anyone confirm that the Wall Charger definitely doesn't have these issues? No manual references, someone who's actually done it. I just cant see how the wall connector can override the cars computer to ignore the start time.

We were contemplating a second mobile cord to leave in the car, but if the actual wall charger is smarter it might be worth the extra $280 for peace of mind.

Neither one is smart in that way. You are thinking it is the cord or wall connector that "forces" or initiates charging, but that's not so. Therefore the type of equipment won't make a difference. It is the car that initiates charging. I've seen this problem reported elsewhere on this forum, and the problem is with the car not waking up to start the charging again. I don't know if there is a solution to this other than what you have noticed: if you have charging scheduled, you would have to go wake the car up somehow, or if you have charging not scheduled, it seems to restart on its own.

 

[rhaekar]

Easy test. Schedule your charging to start and as soon as it starts go flip the breaker then turn it back on after a little bit and see what happens.

Better than waking up and having to go hit a supercharger.

 

[Gonzo's M3]

Hi everyone
Came home from work today to a neighborhood power outage for the last 5 hours
Is it safe to leave my M3 plugged in overnight (using second-gen mobile connector) to start charging when the power returns?
Note the car wasn't charging before the power outage, so not an interruption
Thanks!

 

[brkaus]

Hi everyone
Came home from work today to a neighborhood power outage for the last 5 hours
Is it safe to leave my M3 plugged in overnight (using second-gen mobile connector) to start charging when the power returns?
Note the car wasn't charging before the power outage, so not an interruption
Thanks!

Sometimes power doesn’t come back in the cleanest way. If possible, I would try to avoid it.

But yes, it should work.

 

[srs5694]

Hi everyone
Came home from work today to a neighborhood power outage for the last 5 hours
Is it safe to leave my M3 plugged in overnight (using second-gen mobile connector) to start charging when the power returns?
Note the car wasn't charging before the power outage, so not an interruption

If the car goes to sleep between the time when you plug it in and when the power returns, the car might not notice that the EVSE is now making power available. This happens when trying to use the timed charging features of at least some EVSEs that provide this feature. This has been discussed with respect to some J1772 EVSEs, but I don't know if the same is true of Tesla's EVSEs, or if restoring power might change the equation.

In any event, this doesn't directly address the question of whether it's safe. As @brkaus notes, power might be a bit unstable as it's restored, so personally, I wouldn't want to risk it. For both reasons, unless you're really desperate to get the charge, it might be better to just leave the car unplugged and plan to charge longer the next night, or even swing by a public charger during the day, if that's necessary.