Car Sitting For 3 Weeks In Hot Garage - Charge Or Not?

[Marcust99]

Ok so I'm going to be away for just over 3 weeks soon. I live in an extremely hot climate (Phoenix) and my car will be sitting
in my garage for that time. Unless i keep the AC on in my garage that whole time (not a fan of that idea), the garage will
easily reach 100 degrees every day.

Should I charge it to say 90% before I leave and just let it sit unplugged?

I realize Tesla's stance is to keep it plugged in but I'm concerned about the heat and possible heat issues with the
14-50 charger being plugged in so long. Last thing I need is a fire.

What have folks done in my situation?

Thanks in advance.

 

[jcanoe]

The Tesla Model Y will cool the battery pack as needed if the temperature of the cells within the battery pack get too warm by circulating coolant, running the radiator fan and also running the AC.

I would set the charging threshold to somewhere around 60% state of charge and leave the Tesla plugged in. The Tesla will charge as required if the battery charge falls ~5% to 10% below the set limit. If you are concerned about charging at 240V/32A you can set the maximum charging amperage lower but there is no need.

If you set up Scheduled Charging you can set a time each day when the Tesla Model Y will start charging. This way you can ensure that charging only happens during the early morning hours when the temperature inside the garage is a bit cooler.

 

[Marcust99]

The Tesla Model Y will cool the battery pack as needed if the temperature of the cells within the battery pack get too warm by circulating coolant, running the radiator fan and also running the AC.

I would set the charging threshold to somewhere around 60% state of charge and leave the Tesla plugged in. The Tesla will charge as required if the battery charge falls ~5% to 10% below the set limit. If you are concerned about charging at 240V/32A you can set the maximum charging amperage lower but there is no need.

If you set up Scheduled Charging you can set a time each day when the Tesla Model Y will start charging. This way you can ensure that charging only happens during the early morning hours when the temperature inside the garage is a bit cooler.

Thanks!

Actually I could just plug the 120 in and that would ease my mind I think about being hooked up to 32 amps the whole time...

 

[Sophias_dad]

Hooked up to 32 amps does not mean drawing 32 amps. In fact, I'd wager that connecting to 32 amps/240 is actually safer than 120v. At 120V when the car's AC comes on it'll be drawing all of that 12A/120V's power to cool the car. On a 32 amp/240 circuit, it'll be drawing maybe half the circuits capacity.

 

[jcanoe]

The NEMA 14-50 receptacle is rated for 50A, when charging an EV the maximum amperage is reduced by 20% to 40A. When charging at 32A (the maximum for the Gen2 Mobile Connector) the circuit and receptacle is drawing 32A/50A or 64% of the circuit maximum. If you have confidence that the wiring is correct for the circuit, is installed properly and the plug and receptacle are not damaged then there is little risk.

When charging at home using the Tesla Mobile Connector don't let the Mobile Connector hang supported by the power plug adapter. Tesla sells a Cable Organizer that includes a mounting bracket for the Mobile Connector chassis. You can find similar products on Amazon or fashion your own support/mount for the Mobile Connector chassis.

 

[Marcust99]

The NEMA 14-50 receptacle is rated for 50A, when charging an EV the maximum amperage is reduced by 20% to 40A. When charging at 32A (the maximum for the Gen2 Mobile Connector) the circuit and receptacle is drawing 32A/50A or 64% of the circuit maximum. If you have confidence that the wiring is correct for the circuit, is installed properly and the plug and receptacle are not damaged then there is little risk.

When charging at home using the Tesla Mobile Connector don't let the Mobile Connector hang supported by the power plug adapter. Tesla sells a Cable Organizer that includes a mounting bracket for the Mobile Connector chassis. You can find similar products on Amazon or fashion your own support/mount for the Mobile Connector chassis.

Thanks. Good info.

And I do have my charging brick supported

 

[FFR6288]

My garage is frequently hotter than 105, but I just leave the cars plugged in all the time - with cabin overheat protection turned OFF.

 

[Marcust99]

My garage is frequently hotter than 105, but I just leave the cars plugged in all the time - with cabin overheat protection turned OFF.

Yeah my garage gets super hot but I'm just going to set it to 50% charge and use the 110 plug that was I'm thinking it'll draw less
heat on the brick then using the 15-40 plug.

 

[brinox]

Yeah my garage gets super hot but I'm just going to set it to 50% charge and use the 110 plug that was I'm thinking it'll draw less
heat on the brick then using the 15-40 plug.

The brick is actually a large electrical gate/breaker switch of sorts (lookup EVSE on Youtube) with some logic built in to make sure both ends of the circuit are in compliance with the rated receptacle and wiring. So heat isn't ever really a factor on the mobile connector (and the wall connector for that matter). The charger for your EV is built into the car in fact...

However, your thought about using the 120v outlet in terms of efficiency is wrong - electricity is almost always transmitted/moved more efficiently at higher voltages. As previously referenced, your Tesla will turn on some/all of its cooling systems if the battery packs get too hot. The amount of energy moving through your 120v circuit will actually cost you slightly more than using a 240v circuit due to transmission losses through heat on the smaller wiring.

I would only use the 120v option if there is no 240v circuit available.

 

[Silicon Desert]

The Tesla Model Y will cool the battery pack as needed if the temperature of the cells within the battery pack get too warm by circulating coolant, running the radiator fan and also running the AC.

I would set the charging threshold to somewhere around 60% state of charge and leave the Tesla plugged in. The Tesla will charge as required if the battery charge falls ~5% to 10% below the set limit. If you are concerned about charging at 240V/32A you can set the maximum charging amperage lower but there is no need.

If you set up Scheduled Charging you can set a time each day when the Tesla Model Y will start charging. This way you can ensure that charging only happens during the early morning hours when the temperature inside the garage is a bit cooler.

yes, this ^^^

 

[dhrivnak]

Ok so I'm going to be away for just over 3 weeks soon. I live in an extremely hot climate (Phoenix) and my car will be sitting
in my garage for that time. Unless i keep the AC on in my garage that whole time (not a fan of that idea), the garage will
easily reach 100 degrees every day.

Should I charge it to say 90% before I leave and just let it sit unplugged?

I realize Tesla's stance is to keep it plugged in but I'm concerned about the heat and possible heat issues with the
14-50 charger being plugged in so long. Last thing I need is a fire.

What have folks done in my situation?

Thanks in advance.

I keen mine plugged in. That is not too hot for the charger. And remember most leave their stoves, dryers, heat pumps and hot water heaters plugged in when they leave without issue.

 

[Charliek]

I agree on the leaving it plugged in and at a mid level charge 50-60% is probably all it needs you will get about 2% phantom drain possibly daily if it wakes up and it probably will if your garage gets hot and the battery needs to be cooled (I have walked up to the car it it has been " on" some times doing that when it gets hot enough, that unfortunately doesn't help the garage internal temp some times. if you leave it plugged in and it needs to charge it will and wake up at the charging time and charge iif it is still at the setting it wont over charge . you can even check it and charge it remotely if it is plugged in and I ve done that when I am on my way back from a trip . it will give you peace of mind knowing it is plugged in and you don't want to watch it drop down and die while you are away

 

[Marcust99]

The brick is actually a large electrical gate/breaker switch of sorts (lookup EVSE on Youtube) with some logic built in to make sure both ends of the circuit are in compliance with the rated receptacle and wiring. So heat isn't ever really a factor on the mobile connector (and the wall connector for that matter). The charger for your EV is built into the car in fact...

However, your thought about using the 120v outlet in terms of efficiency is wrong - electricity is almost always transmitted/moved more efficiently at higher voltages. As previously referenced, your Tesla will turn on some/all of its cooling systems if the battery packs get too hot. The amount of energy moving through your 120v circuit will actually cost you slightly more than using a 240v circuit due to transmission losses through heat on the smaller wiring.

I would only use the 120v option if there is no 240v circuit available.

Wow thanks for posting that. I'm learning a lot.

So I guess I'll let it plugged into the 15-40 then.....

 

[Silicon Desert]

So I guess I'll let it plugged into the 15-40 then.....

yes, but don't forget to set the charging level at a decent mid-range

 

[Marcust99]

yes, but don't forget to set the charging level at a decent mid-range

yeah I'm thinking 50%....

 

[Jejunjm]

Wow thanks for posting that. I'm learning a lot.

So I guess I'll let it plugged into the 15-40 then.....

I'd also suggest in addition to the efficiency improvement on 240 the wiring is new, appropriately sized for current/length and indicated for continuous draw - unlike some home wiring. For maintenance of temperature (battery and interior) I've noticed no more then 15 amps @ 240 - in Tucson with a 100+f garage.

 

[fortunex]

Last month during the record temps of 115+ Fahrenheit, my uninsulated garage would reach 120 or higher. At the same time, my 120V connection wasn't drawing 12A - - it dropped down to 4A. I was concerned until I researched the Mobile Connector and discovered the operating range is 120F max, so it was seemingly doing its job safely.

The Mobile Connector is warm to the touch anyways, and on those days it was scorching. One thing to check is make sure there are no flammable substances or soft materials like towels or paper near the connector or below it.

If the connector is mounted on the wall with a module that supports it by looping the cable through it, it can fall down if the cable slides back. This happened to me over a few weeks when I first installed the mount and improved after adding some support to the connector and making sure the loop wasn't touched when placing the adapter in / out of the holster.

This style of wall module holder seems not completely functional to me, but what do I know.....

 

[KiloV]

The Tesla Model Y will cool the battery pack as needed if the temperature of the cells within the battery pack get too warm by circulating coolant, running the radiator fan and also running the AC.

You really don’t want the car to be doing a lot of cooling in an enclosed garage… there’s nowhere for waste heat to go, and it’ll just wind up being a really inefficient space heater.

Have you checked the optimum temperature range for the pack? I suspect that’s documented somewhere or even known by all the data loggers here on TMC. My guess would be that 100F isn’t high enough to harm the pack, so just leaving it sit on the charger should be fine.

When my car is going to be sitting in the garage for a long time, I charge it to 80%, set the charging limit down to 50%, and leave it plugged in. That way it doesn’t try to charge while I’m away, but it has wall power available if needed (typically for heating, in my case). When I’m getting on the flight home, I wake the car from the app and adjust/start charging if needed.

Dunno about Phoenix, but it works for me.

 

[jcanoe]

You really don’t want the car to be doing a lot of cooling in an enclosed garage… there’s nowhere for waste heat to go, and it’ll just wind up being a really inefficient space heater.

Have you checked the optimum temperature range for the pack? I suspect that’s documented somewhere or even known by all the data loggers here on TMC. My guess would be that 100F isn’t high enough to harm the pack, so just leaving it sit on the charger should be fine.

When my car is going to be sitting in the garage for a long time, I charge it to 80%, set the charging limit down to 50%, and leave it plugged in. That way it doesn’t try to charge while I’m away, but it has wall power available if needed (typically for heating, in my case). When I’m getting on the flight home, I wake the car from the app and adjust/start charging if needed.

Dunno about Phoenix, but it works for me.

You can't control when the Tesla Model Y will cool the battery pack. The Tesla may circulate coolant through the pack and the vehicle's radiator. The radiator fan can come on, the AC compressor may also be turned on. If I am leaving for a week my Tesla Model Y is safer in my garage than on my driveway or at an airport parking lot.

 

[drtimhill]

Yeah my garage gets super hot but I'm just going to set it to 50% charge and use the 110 plug that was I'm thinking it'll draw less
heat on the brick then using the 15-40 plug.

I dont think you have that right. The car has a fixed overhead during charging regardless of power draw, and so the total energy draw is optimal when the car charges at a higher current for a shorter time, because the faster charge time minimizes the times that the car is drawing that fixed overhead. As others noted, you are better off using the 14-50 and just setting a max current to give you peace of mind when you are away.

And I'm not sure you want any cabin overheat protection. That will keep the cabin cooler, but at the expense of pumping more heat into you garage (A/C is a heat pump, remember), which means the garage and the non-cabin parts of the car will be even hotter.