model 3 charging in garage

[nvesprini]

hi all

new to the forums so apologies if this is in the wrong place, please redirect as needed.

does anyone know a rough estimate for the power draw from the car to heat or cool the battery? not interested in the cabin overheat protection...just purely the energy needed to keep the battery warm in the winter and cool in the summer. the reason i ask is that my garage gets cold (-10 to -15C in the winter) and warm (above 35C) in the summer. im debating putting in a 14-30 (30amp, 24 usable) or 14-50 (50 amp, 40 usable) line. i can live with the 14-30 assuming the battery heating/cooling doesnt take too much away from charging. from what ive read you get about 30km range an hour on a 14-30 socket. thats fine for my needs. however if for example the car is drawing 6 amps to cool the battery (or to heat in winter) then im really only drawing 18 of my 24 amps for the battery charging...which is about 20km of range an hour. these numbers are just for an example...i have no idea what a typical draw is for the heating or cooling loops so i dont know if i should expect a minimal or massive drop once the weather hits either extreme.

any help you can offer is appreciated. if you have a 14-30 line and have a hot or cold climate what is the typical charging range you get?

thanks kindly

 

[user212_nr]

The charging will be more efficient with 50A, or even 60A (via the wall connector, if you have the LR).

30A is also sufficient, but you do not explain what is the negative about 50A for you. Do you not have enough power? Or are you concerned about the extra cost of the wire?

People do report issues charging on 120v sockets in cold weather. The battery probably heats itself enough after a certain point from charging that there is no longer any energy used for heat.

Just install 50 or 60 amps unless you have a good reason not to.

 

[nvesprini]

Since the car will sit overnight a 30a 240v line at 30k/hr range seems fine......unless the heating/cooling draws off a large chunk of power (hense the question). I'd also be using the mobile charger which is capped to 32a (I think). 50a or higher line requires a lot more money to run the line (long run in my house) as well as a wall charger to take advantage of the extra current....all for a charging rate I wouldn't necessarily need.....again assuming the heating/cooling of the battery isn't high power.

Ideally I'd split the difference and run a 40a line on a 14-50 socket and use the mobile charger to it's full capacity but that's not to Ontario electrical code. A 14-50 needs a 50a line unless it's a range.

It's also my understanding that 240v is around 85 percent efficient....regardless of amperage. Am I mistaken?

 

[nvesprini]

Should have also mentioned my pannel is limited and 50a or higher will likely blow my main breaker to the house.

 

[MN3SRPlus]

I live in the Twin Cities and charge my car off a 14-30 in my drive way. I got the car late November of last year. We saw temps down to -15F/-25C last winter. 30amp/240volt is plenty for charging in those conditions.

If you set the HVAC to MAX a 14-30 cannot fully keep pace and you will slowly draw down the battery.

I wanted a 14-50 but my panel couldn’t support it. I haven’t run across a situation where the 14-30 wasn’t enough.

 

[user212_nr]

Should have also mentioned my pannel is limited and 50a or higher will likely blow my main breaker to the house.

You should be fine with the 30A plug then. You don't want to push the panel's capacity to its limits.

The battery is heated by charging, so I don't think that it uses any power for heating the battery except if it is cold to start with. 30A @ 240V should be well past the point where it will cool down again while charging.

 

[MN3SRPlus]

I should also mention, TeslaBjorn has several YouTube videos where he uses ScanMyTesla (iirc) to dig into the power draw of the Model 3’s subsystems. Off the top of my head the cabin heater is around 7kw, and battery heating is like 4kw rear motor and 3.5kw front motor. Those were both maximums.

You also asked about cooling, I don’t know the exact numbers, but I was able to pre cool my cabin while plugged into a 15a/120v outlet without drawing down my car’s SOC the other day. It was parked in full sun and 85f/30c ambient. I ran it for about half an hour.

 

[jeremymc7]

I would heavily recommend putting insulation on the garage door. I have insulated panels but added solid foam in solar ion on the inside. Also added heavy duty rubber gasket on door bottom and edges. This has made a huge difference to temp control in winter and summer and cost almost nothing. It’s also nice to have more climate control without using any energy.

 

[mrau]

You will be fine with a 30 amp circuit, especially in a garage. In the winter any garage is warmer than sitting outside in the windy cold weather.

When arriving home in the evening is when most folks plug in their car. The battery is already up to the correct temp and will charge to your set level within a few hours (depending how much you drove). After it is charged you could plug the car into a regular 120 volt outlet and it would still maintain battery temps without any loss of range. So using a 240 volt 30 amp will be no problem.

 

[nvesprini]

thanks very much everyone. that settles it for me!

cheers!

 

[camalaio]

Quickly skimmed and I don't think anyone mentioned cooling.

Just to clarify then, it doesn't really cool the battery much at those temps. It would need to be a bit warmer to do so.

One more point regarding warming though, the difference between plugs will mostly be in total charge time, but not the way you might think, and depends on if you have a RWD or AWD.

The AWD will pull most or all of the power available until it is warmed, then begin charging at the full available power.
The RWD will pull what it can for heating, with the rest going immediately to charging. It can use the full charge power once the battery is warmed.

So AWD charging will be delayed by the more or less same between these two options, but a RWD will start charging some amount right away. Both options you have are enough power to overcome the cold though; it's only 120V/12A that's not really workable in those conditions.

 

[nvesprini]

Quickly skimmed and I don't think anyone mentioned cooling.

Just to clarify then, it doesn't really cool the battery much at those temps. It would need to be a bit warmer to do so.

One more point regarding warming though, the difference between plugs will mostly be in total charge time, but not the way you might think, and depends on if you have a RWD or AWD.

The AWD will pull most or all of the power available until it is warmed, then begin charging at the full available power.
The RWD will pull what it can for heating, with the rest going immediately to charging. It can use the full charge power once the battery is warmed.

So AWD charging will be delayed by the more or less same between these two options, but a RWD will start charging some amount right away. Both options you have are enough power to overcome the cold though; it's only 120V/12A that's not really workable in those conditions.

thanks very much for this. its a RWD but i wasnt aware the charge vs heating setup changes from model to model. great info! much appreciated

 

[SigNC]

Also, if it truly gets that cold in your garage it may make more sense to just charge when you get home from your drive and hopefully the battery is above freezing. That would allow you to charge without "wasting" electricity to warm the battery. If your goal is to leave in the AM with regen however, it would make more sense to charge it before you leave.