Fire Safety - Multiple Teslas in Attached Garage

[GateFather]

Just installed a second Tesla Wall Connector in my garage for our second Tesla. I now have a 2018 Model 3 LR and a 2023 Model Y LR charging in my attached garage to my home. My twin daughters' room is directly above the garage. The installation was done according to code and by a professional licensed electrician, but I am still wanting to add some safety measures just in case. I already added a hardwired Nest Protect and used IFTTT to basically make my entire house go absolutely nuts if there is a fire in the garage (lights flashing, loud sirens inside on all (many) echo devices around the house and messages in kids room telling them to evacuate etc. Also turn on the sprinklers near the garage...not that it would really help but....why not. What I am really wondering, is if there is anything else I can/should do? I've read that battery fires are really just all about a LOT of water for a long time to try to manage. But, is anyone aware of anything else I could put in the garage that might help at all should a fire break out?

 

[RTPEV]

What car did you have before the second Tesla? Did it run on gas? If so, do whatever you did for that car, because that was 10X more likely to catch fire than your Tesla. You are now much safer than you were before.

Okay, a bit of a snarky response...but I do get it. You obviously want to be as safe as possible, but the frequency of EV fires is way blown out of proportion by the media. You've already taken probably 5 times more precautions than the average person. If you are 100% risk adverse and want to not just mitigate risk but actually eliminate it, then park the cars outside >20 feet from any structure and only charge when you are awake and actively monitoring the process. This is pretty much completely unnecessary mind you, but that's the cost of eliminating risk and not evaluating the likelihood in your mitigation strategy.

 

[GateFather]

What car did you have before the second Tesla? Did it run on gas? If so, do whatever you did for that car, because that was 10X more likely to catch fire than your Tesla. You are now much safer than you were before.

Okay, a bit of a snarky response...but I do get it. You obviously want to be as safe as possible, but the frequency of EV fires is way blown out of proportion by the media. You've already taken probably 5 times more precautions than the average person. If you are 100% risk adverse and want to not just mitigate risk but actually eliminate it, then park the cars outside >20 feet from any structure and only charge when you are awake and actively monitoring the process. This is pretty much completely unnecessary mind you, but that's the cost of eliminating risk and not evaluating the likelihood in your mitigation strategy.

Completely understand what you are saying and I'm always the first to call BS on things like this. I'm not worried at all because the Tesla is "more likely to start a fire" or anything along those lines. I know ICE fires are way more common. In fact, before the second Tesla we had a Honda Odyssey minivan but parked it on the driveway. Not for safety related concerns, but just because we had "stuff" on the other side of the garage that we now cleaned out to fit the other Tesla and be able to have them both charging when parked in there.

I'm just thinking that 150kW of combined electricity sitting in the garage and 80 Amps flowing at 220V with multiple wires, connections, etc are more likely to cause a fire than gasoline sitting in the tank of an ICE vehicle would be. Just so much potential energy in that one space, under my girls' room. You're probably right though, I think having the smart smoke detector in there is probably good.

 

[MP3Mike]

I'm just thinking that 150kW of combined electricity sitting in the garage and 80 Amps flowing at 220V with multiple wires, connections, etc are more likely to cause a fire than gasoline sitting in the tank of an ICE vehicle would be. Just so much potential energy in that one space, under my girls' room.

Sure, you have 150kWh of energy in two Teslas, but do you realize that two ICE vehicles with 14 gallon tanks that are full have ~900 kWhs of energy stored in them? (More than 6 times the amount of energy in your Teslas.)

 

[RTPEV]

Completely understand what you are saying and I'm always the first to call BS on things like this. I'm not worried at all because the Tesla is "more likely to start a fire" or anything along those lines. I know ICE fires are way more common. In fact, before the second Tesla we had a Honda Odyssey minivan but parked it on the driveway. Not for safety related concerns, but just because we had "stuff" on the other side of the garage that we now cleaned out to fit the other Tesla and be able to have them both charging when parked in there.

I'm just thinking that 150kW of combined electricity sitting in the garage and 80 Amps flowing at 220V with multiple wires, connections, etc are more likely to cause a fire than gasoline sitting in the tank of an ICE vehicle would be. Just so much potential energy in that one space, under my girls' room. You're probably right though, I think having the smart smoke detector in there is probably good.

The two batteries do not "communicate" in any way, so while it's true that technically speaking you are twice as likely to suffer a fire (although it's 2X a VERY small number), it has nothing to do with the fact that you have twice as much battery material sitting in the garage. The chances of both vehicles spontaneously combusting at the same time (without some really obvious external cause) is infinitesimally small.

Sure, you do have twice as much battery material sitting in the garage, and one catching fire would almost certainly catch the other on fire, but the difference between one and two in terms of the risk it poses is pretty small. Even with one in there, if a fire did start, you are going to want to get out of there. The second one doesn't really add to the danger level. Besides, EV fires build relatively slowly so you should have enough warning to evacuate before anything reached the second vehicle anyway.

But let's talk about your charging situation.

I have a Model 3 and a Model Y as well. We have a single 30A EVSE that is plenty for us (full disclosure, I am getting an actual Tesla wall connector installed, but it's more due to the fact that we used to have two EVs with charge ports at the front of the vehicles so the current EVSE is in the back of the garage, while now that we have two Teslas, relocating the charger makes sense, and our utility has an EVSE rebate program that would be silly not to take advantage of). The point is, we almost never charge on the same day. We used to when we had two short range EVs that needed to be charged the same day, but nowadays, we each only charge every few days, and we easily coordinate which day each of us charges without impact. Unless you have extreme needs, I suspect that the amount of time both cars will be actively charging will be minimal (or at least you could intentionally minimize it if you wanted). And charging even at 30A is plenty sufficient to complete a charge in a single overnight session (we tend to plug in when we get down to 30% and charge to 80% and usually charging starts by 9:30 and completes by 3:30. If you are super worried, just set the charge rate down to 30A or even 24A.

But again, properly installed wiring should pose no more risk than your oven or clothes dryer or A/C unit. If done to code, there is plenty of safety margin to keep you safe.

 

[GateFather]

The two batteries do not "communicate" in any way, so while it's true that technically speaking you are twice as likely to suffer a fire (although it's 2X a VERY small number), it has nothing to do with the fact that you have twice as much battery material sitting in the garage. The chances of both vehicles spontaneously combusting at the same time (without some really obvious external cause) is infinitesimally small.

Sure, you do have twice as much battery material sitting in the garage, and one catching fire would almost certainly catch the other on fire, but the difference between one and two in terms of the risk it poses is pretty small. Even with one in there, if a fire did start, you are going to want to get out of there. The second one doesn't really add to the danger level. Besides, EV fires build relatively slowly so you should have enough warning to evacuate before anything reached the second vehicle anyway.

But let's talk about your charging situation.

I have a Model 3 and a Model Y as well. We have a single 30A EVSE that is plenty for us (full disclosure, I am getting an actual Tesla wall connector installed, but it's more due to the fact that we used to have two EVs with charge ports at the front of the vehicles so the current EVSE is in the back of the garage, while now that we have two Teslas, relocating the charger makes sense, and our utility has an EVSE rebate program that would be silly not to take advantage of). The point is, we almost never charge on the same day. We used to when we had two short range EVs that needed to be charged the same day, but nowadays, we each only charge every few days, and we easily coordinate which day each of us charges without impact. Unless you have extreme needs, I suspect that the amount of time both cars will be actively charging will be minimal (or at least you could intentionally minimize it if you wanted). And charging even at 30A is plenty sufficient to complete a charge in a single overnight session (we tend to plug in when we get down to 30% and charge to 80% and usually charging starts by 9:30 and completes by 3:30. If you are super worried, just set the charge rate down to 30A or even 24A.

But again, properly installed wiring should pose no more risk than your oven or clothes dryer or A/C unit. If done to code, there is plenty of safety margin to keep you safe.

Thanks for the comments. I really am not super worried. Just want to do my due diligence on the subject, and I feel satisfied at this point that I have. I also realized the batteries do not communicate with each other. However, both pulling 40amps does put an 80amp load on the 100amp breaker that goes to the subpanel. Even still, I am satisfied that I'm good and won't worry further about it. Appreciate it!

 

[RTPEV]

However, both pulling 40amps does put an 80amp load on the 100amp breaker that goes to the subpanel.

...which is designed to tolerate 80A continuous current...well technically the breaker is designed to trip at 100A...what is designed to tolerate 80A continuous current is the wiring between the main panel and the subpanel. So you should be fine if done properly and according to code.

But still, I think you'll find that you probably won't need to be running both at the same time (at least not for long).

 

[CapsEngineer]

Just installed a second Tesla Wall Connector in my garage for our second Tesla. I now have a 2018 Model 3 LR and a 2023 Model Y LR charging in my attached garage to my home. My twin daughters' room is directly above the garage. The installation was done according to code and by a professional licensed electrician, but I am still wanting to add some safety measures just in case. I already added a hardwired Nest Protect and used IFTTT to basically make my entire house go absolutely nuts if there is a fire in the garage (lights flashing, loud sirens inside on all (many) echo devices around the house and messages in kids room telling them to evacuate etc. Also turn on the sprinklers near the garage...not that it would really help but....why not. What I am really wondering, is if there is anything else I can/should do? I've read that battery fires are really just all about a LOT of water for a long time to try to manage. But, is anyone aware of anything else I could put in the garage that might help at all should a fire break out?

From First Alert.

"Should I put smoke/CO alarms in my unfinished attic, crawlspace, or garage?​

No. We do not recommend installing smoke or carbon monoxide detectors in unfinished areas of the home. This includes attics, crawlspaces, garages, unheated areas, or porches.

The sensors in smoke and CO alarms work best in temperatures between 40° F (4° C) and 100° F (38° C). Alarms in unfinished areas may experience more nuisance alarms due to temperature fluctuations.

To protect an unfinished area of your home like a garage, try a First Alert heat alarm. This type of detector can supplement your smoke alarm system. A First Alert heat detector senses dangerous temperatures of 135° or more."​

I realize yours is a Nest Protect, but when I was looking to put a Nest Protect in my garage well, I found similar answers from lots of different resources. I put mine above the door that is the entrance to the garage. This was ~2017 and I couldn't find a connected heat alarm at the time so I didn't put anything in the garage.

 

[GateFather]

From First Alert.

"Should I put smoke/CO alarms in my unfinished attic, crawlspace, or garage?​

No. We do not recommend installing smoke or carbon monoxide detectors in unfinished areas of the home. This includes attics, crawlspaces, garages, unheated areas, or porches.​

​

The sensors in smoke and CO alarms work best in temperatures between 40° F (4° C) and 100° F (38° C). Alarms in unfinished areas may experience more nuisance alarms due to temperature fluctuations.​

​

To protect an unfinished area of your home like a garage, try a First Alert heat alarm. This type of detector can supplement your smoke alarm system. A First Alert heat detector senses dangerous temperatures of 135° or more."​

I realize yours is a Nest Protect, but when I was looking to put a Nest Protect in my garage well, I found similar answers from lots of different resources. I put mine above the door that is the entrance to the garage. This was ~2017 and I couldn't find a connected heat alarm at the time so I didn't put anything in the garage.

Yeah I guess technically it wouldn't be to code, but I'll see how it holds up. It definitely goes below 40F degrees in the winter and occasionally above 100F in the summer where I am in NJ.

 

[father_of_6]

I take @GateFather's post to be more about the battery than the charging infrastructure... otherwise there'd also be concern about an electric dryer and electric stove. I have a kiln in my basement that we fire to ~2300°F.

While it is true that ICE vehicles have caused a lot more fires than EVs, batteries in general have caused plenty of their own fires... laptop batteries, phone batteries, e-bikes, etc.

I park outside, but if I parked in an attached garage I might share the same concern. I think the best solution, short of parking away from your home, is what you've already done - ensure that you have adequate alarms so that you get warned of any problems as early as possible.

Tesla has sold close to 5 million cars at this point. There have been very few fires from Tesla's cars, even fewer where there wasn't an accident... and in some cases those seem suspect, as if it was started intentionally for negative press against Tesla (like the auto insurer that started a Model S on fire to "prove" they are dangerous).

I think you're right to not worry, but wise to also take as much precaution as possible.

 

[SVMike]

Thanks for the comments. I really am not super worried. Just want to do my due diligence on the subject, and I feel satisfied at this point that I have. I also realized the batteries do not communicate with each other. However, both pulling 40amps does put an 80amp load on the 100amp breaker that goes to the subpanel. Even still, I am satisfied that I'm good and won't worry further about it. Appreciate it!

I would think that if the load on the 100 amp breaker was the critical issue and a fire broke out it would not affect the car(s) and batteries for some time. just my guess. And i would think that a problem here would be handled by the breaker tripping before a fire were to ever start, having nothing to do with the car(s). You could test this a couple of ways, just to sleep better. Firest, measure the wire temps with a IR thermometer after a couple of hours of dual charging. Not sure what you compare this to, but the wires should be only "warm" to the touch.
Simulate a fault by adding 20+ amps to the same circuit with a couple of hair dryers, for example and see that the breaker trips.
Not sure if you really want to do this when you have two expensive cars plugged in...but they are supposed to handle a power loss with no problem.

In any case, the relevant comparison isn't really how many more ICE car fires there are per capita than EV fires. It is how many ICE cars fires spontaneously happen in a garage (eliminates fire after being damaged or at a gas station when someone is smoking, for example) vs undamaged EVs catching fire while charging. (Too bad the original Bolt EV had this issue).

You could also lower the charging amps on your cars to a lower number when you charge at night or unattended

 

[shrinkwrap]

I would consider Ting (tingfire.com), a plug-in sensor that constantly monitors the electrical system in your home and alerts you to any potential risk of electrical faults, incuding fire. I've had it for several months, and it seems to work.

 

[snorp]

I already added a hardwired Nest Protect and used IFTTT to basically make my entire house go absolutely nuts if there is a fire in the garage (lights flashing, loud sirens inside on all (many) echo devices around the house and messages in kids room telling them to evacuate etc.

I would like to do this also. Is it all done through the Alexa app?

 

[Don.Church]

I suggest an annual inspection of the electrical wires and circuits by a licensed electrician to calm any concerns.

 

[cbdream99]

I think some cities in CA require heat alarm installation in the garage for solar battery installation, and you may consider adding that. There are fire retarding dry walls that may delay fire spread giving you more time to escape, check the wires periodically for temperature and wears. but I wouldn't lose sleep over it.

 

[Darmie]

I would check your cables to see if they are warm and if anything i would turn down the amperage of your chargers to give them move overhead. You didn't mention what amp breaker they are on and or what amperage your HPWC are set on. The 3 I have are set to only max charge to 40 amps vs 48. you can always set them to go lower in amperage if you are concerned. To me, the only concern would be the amp draw of each HPWC, the wire that was used along with the amp of breakers that were used.
If by chance they are not on their own dedicated circuit, the HPWC's can do load sharing between the two vehicles while charging.

I would consider Ting (tingfire.com), a plug-in sensor that constantly monitors the electrical system in your home and alerts you to any potential risk of electrical faults, including fire. I've had it for several months, and it seems to work.

I attempted to look for some honest reviews on this and couldn't find much that didn't come from the company. What's the monthly charge for?

 

[MP3Mike]

I attempted to look for some honest reviews on this and couldn't find much that didn't come from the company. What's the monthly charge for?

I don't know what the monthly charge is, as my insurance company, State Farm, provides the service free of charge. (I assume because they see it lowering fire claim risks, and paying for it is cheaper than paying for the fire claims that it prevents.)

As far as a review for it, all I can say is I have one. It has never identified an issue for our house, but we haven't had an electrical issue/fire either.

 

[rlsd]

I would consult an electrician who knows about Tesla cars to add what is needed for both cars.
Also A/C and electric water tank use may need higher load.

 

[GateFather]

I would like to do this also. Is it all done through the Alexa app?

It was done in IFTTT app (if this than that). However, after I wrote this I went in to check that my integration for this that I setup way back for another Nest Protect was still setup. It is not and Google apparently butchered their API access for Nest Protect - so this does not work anymore like it used to

 

[dakhlkt22]

My insurance company gave me a $300+ discount for having a security system that is connected to central monitoring. Most of these central monitoring companies (e.g. Simplisafe, ADT, etc) charge around $30/mo, so the insurance discount basically pays for the central monitoring. I just had to pay the up front cost of the cameras, monitors and sensors.

I put a smoke detector sensor and a temperature sensor in the garage. If there is a fire in the garage, it will trigger a central monitoring alarm and if I don't respond or clear the alarm, central monitoring will dispatch emergency services.