120 v. or 240 v.?

[daniel]

Back in SpokaneI had 240 v. 50 a. in my garage on a NEMA 14-50 outlet. Here in Maui I only have 120 v. in the garage. 120 v. is plenty to get all the charge I need, because I don't drive a lot and I have the LR battery. (Didn't know I'd be moving here when I ordered the car.)

Pretty soon I'm having solar installed, and if I want to I can have a 240-v. outlet installed in the garage.

Is the car better off charging at 240 v. or at 120 v.? Note that the time it takes to charge does not matter to me because with the amount I drive 120 v. is plenty fast enough, and with solar, it won't matter how much electricity I use. The only thing I care about is what's better for the car.

Thanks for any information.

 

[dhrivnak]

I would go for the 240V. I know on the Roadster battery cooling was disabled on 120V as there was not enough power to run the AC. And for those few times you may need faster than 4-5 mph 240v is handy.

 

[SSedan]

On 120volts the computers and all are using a significant portion of the available power so is less efficient.
I would do 240v and manually dial it down to something the solar is happy with.

 

[ewoodrick]

It doesn't matter.

And is SSedan would think about it, it's the same amount of energy

 

[eprosenx]

I would do a 240v receptacle regardless, it is more efficient charging since you cooling pumps run less time (and it might save you a tiny amount of energy). If you can put the receptacle right next to the breaker panel and are already having work done, it is stupid cheap to have done, so why not... If you even wanted to be really cheap then just do a 6-20 adapter. That gives you 16a @ 240v which is vastly faster than the 12a at 120v you have right now (presumably).

I am not a fan of charging off any circuit that is not dedicated. Regardless of 120v vs 240v, I would want a dedicated circuit no matter what. Otherwise it is daisy chained from receptacle to receptacle which is more points of failure and if you car is maxing 12 amps continuous on a 15a circuit then you have zero headroom to run anything else on the circuit.

 

[esrandl]

240v is just hype. don't spend the money unless you have some other reason to have 240v outlet. It is impossible you will drive enough on Maui to not overnight recharge with just 110V (about 40-50 mi in 8-9 hrs). I used a standard 110v outlet for three years stateside and never had any problems despite driving with no restrictions. Seriously, who drives 260+ miles then returns home to charge quickly and drives another 260 miles? That's something like 8-10 hours of just driving car.

The funny thing is: I did end up getting a 240v outlet and it makes no difference. I plug in when I get home and the 50 mi or so I drove gets recharged just like before. I still use the mobile charger daily with no issues as well.

The only logical basis for 240v I can think of is if you drive >150 mi round trip on a daily basis. 110v prob wouldn't keep up with that.

 

[Galve2000]

sorry for the noob question.. is the M3 capable of pulling 48 Amps form a 240 V source? what is the max amperage you can pull from the HPWC?

 

[brkaus]

sorry for the noob question.. is the M3 capable of pulling 48 Amps form a 240 V source? what is the max amperage you can pull from the HPWC?

The LR is capable. The SR maxes out at 32.

 

[wycolo]

> Pretty soon I'm having solar installed, and if I want to I can have a 240-v. outlet installed in the garage.

Go for it. It makes no sense to do a solar improvement and not include the garage. Think resale value and the possibility of needing RV or equipment powering in said garage. Better to charge car off the full transformer rather than just half (balanced load). Also a chance to replace old outlets, inadequate wiring, ancient breaker boxen, etc.
--

 

[mongo]

Back in SpokaneI had 240 v. 50 a. in my garage on a NEMA 14-50 outlet. Here in Maui I only have 120 v. in the garage. 120 v. is plenty to get all the charge I need, because I don't drive a lot and I have the LR battery. (Didn't know I'd be moving here when I ordered the car.)

Pretty soon I'm having solar installed, and if I want to I can have a 240-v. outlet installed in the garage.

Is the car better off charging at 240 v. or at 120 v.? Note that the time it takes to charge does not matter to me because with the amount I drive 120 v. is plenty fast enough, and with solar, it won't matter how much electricity I use. The only thing I care about is what's better for the car.

Thanks for any information.

Since efficiency is not a concern:
The converter in the car cares about power, current, and voltage. Charging at a lower power rate is less stressful. Charging as a lower current is less stressful. Charging with a higher input voltage may be less stressful, but it depends on the converter setup (is the voltage swing worse than the increase in current for the same power).

If 120V works for you, go with that. However, a low current 240V charge rate likely will make zero difference over the life of the car.

 

[SSedan]

240v is just hype. don't spend the money unless you have some other reason to have 240v outlet. It is impossible you will drive enough on Maui to not overnight recharge with just 110V (about 40-50 mi in 8-9 hrs). I used a standard 110v outlet for three years stateside and never had any problems despite driving with no restrictions. Seriously, who drives 260+ miles then returns home to charge quickly and drives another 260 miles? That's something like 8-10 hours of just driving car.

The funny thing is: I did end up getting a 240v outlet and it makes no difference. I plug in when I get home and the 50 mi or so I drove gets recharged just like before. I still use the mobile charger daily with no issues as well.

The only logical basis for 240v I can think of is if you drive >150 mi round trip on a daily basis. 110v prob wouldn't keep up with that.

I installed a wall connector a few weeks after while I was on vacation I got a call by Dad was getting a couple hour ambulance ride to a hospital 40minutes from my house due to a heart attack(he is fine). I had to plug in at the destination charger at the hotel while we scrambled to get our stuff and the kids packed up. Then had a several hour drive home, plugged in while unloading the car but was using a dryer outlet, when I went to leave and put the hospital in NAV it said round trip was tight so I had to divert to a supercharger for a few minutes, probably 20minutes out of my way including the charge time, but under the circumstance was too long.....
Also I believe redundant charging solutions are prudent, if you have a wall connector and something happens damaging it or the cable, you still have the UMC to fall back on. Also spreads the plug wear across multiple items, I know the Model 3 owners don't believe that is a thing yet but with my 85K mile S the UMC plug to the car is getting worn even after cleaning it runs warmer at 40amps than the HCWC does at twice that. I rarely put on more than 35 miles in a day most are more like 15 and have no regrets on the $700 I spent being able to charge at 58miles per hour though I rarely use it.

All that said if the cable is going to be in or near a walkway I would probably stick with UMC(maybe a second) for the more flexible cable.

Far as if 120volt is easier on things you are getting away carried away with presumptions and ignoring duration as a source of wear. As someone already noted 120volt may cause the coolant pumps to not run and waste what little current is available, I would think this could cause localized warmer spots than if it had enough power to go ahead and circulate.

Even a 15amp 240 circuit is rated at 11 vs. 3-4 for a 15amp 120volt, this is due to the static overhead of the charging electronics and maybe pumps if they run on the 3 with 120volt charging. Twice the power but three times the range added, that is clearly an efficiency advantage

 

[Skotty]

Back in SpokaneI had 240 v. 50 a. in my garage on a NEMA 14-50 outlet. Here in Maui I only have 120 v. in the garage. 120 v. is plenty to get all the charge I need, because I don't drive a lot and I have the LR battery. (Didn't know I'd be moving here when I ordered the car.)

Pretty soon I'm having solar installed, and if I want to I can have a 240-v. outlet installed in the garage.

Is the car better off charging at 240 v. or at 120 v.? Note that the time it takes to charge does not matter to me because with the amount I drive 120 v. is plenty fast enough, and with solar, it won't matter how much electricity I use. The only thing I care about is what's better for the car.

Thanks for any information.

Here's a question -- how long do you plan to live at your place? Is it possible your situation might change? If a 240v is possible and up for consideration, probably a good idea to go ahead and have it installed. 120v will do you for a spell, but in the long run 120v isn't very practical for EVs. You might need the 240v some day, and if you move, the next buyer might see it as a pro to buy your place.

 

[EVDRVN]

I could go on for 20 min about the disadvantages of 120V charging but the biggest issue is safety and that is another long topic. 120V charging is inherently an unsafe method because of the constant load on an outlet and circuit that is generally compromised. 120V use should be relegated at home to a dedicated 20A circuit with a new and high-quality outlet, if you have that then it makes more sense to convert it to a 240V 20A 6-20. Don't use 120V particularly since you don't need to.

 

[eprosenx]

I could go on for 20 min about the disadvantages of 120V charging but the biggest issue is safety and that is another long topic. 120V charging is inherently an unsafe method because of the constant load on an outlet and circuit that is generally compromised. 120V use should be relegated at home to a dedicated 20A circuit with a new and high-quality outlet, if you have that then it makes more sense to convert it to a 240V 20A 6-20. Don't use 120V particularly since you don't need to.

^——— What he said.

Given you are on Maui, range will likely never be an issue, but I would always do a dedicated circuit and as long as you are doing that I would always do a 240v one even if it was only 20a (or even 15a!)

 

[daniel]

Wow. Thanks for all the great comments and information!

To respond to some of the comments:

Here on Maui I will never be driving very far, and since I got the LR battery (hadn't yet thought about moving here when I bought the car) even the slow charge rate of 120 v. is plenty fast enough.

This house is only about 5 or 6 years old so all the wiring and outlets are good.

My solar system will be sized large, so I'll have plenty of power, and the utility will not buy my excess, so efficiency is a moot point. My only concern is what's best for the car (and the house -- thanks to those who mentioned possible strain on the circuit).

While the future is always capricious, my intention is to live out the rest of my life here, and to remain in this house until I need to move to assisted living. So the cost of making the house right is not an issue.

@dhrivnak mentioned above that on 120 v. the car will not run the cooling pumps. This is the most relevant comment to my concerns (thanks!) in part because my garage is hot. I'm actually considering putting A/C in the garage or possibly diverting some cool air from the house. Heat will be an issue here. Maui is hot, especially in summer. Not hot like Phoenix or Florida, but still plenty hot, and with the tropical sun. Knowing this, I might not wait for the solar to be installed to have the 240 v. receptacle installed.

Thanks again to everyone for all the help!

 

[Kirby64]

Wow. Thanks for all the great comments and information!

@dhrivnak mentioned above that on 120 v. the car will not run the cooling pumps. This is the most relevant comment to my concerns (thanks!) in part because my garage is hot. I'm actually considering putting A/C in the garage or possibly diverting some cool air from the house. Heat will be an issue here. Maui is hot, especially in summer. Not hot like Phoenix or Florida, but still plenty hot, and with the tropical sun. Knowing this, I might not wait for the solar to be installed to have the 240 v. receptacle installed.

Thanks again to everyone for all the help!

The Model 3 doesn't have this limitation. Everything runs properly even if charging off 120V/12A. That being said, a 240V outlet is probably wise anyways assuming it's cheap enough to do. If it ends up costing you $500++ in conduit and wiring... maybe not worth it. As others have mentioned, 240V is going to be more efficient, but if the cost is going to be 100s of dollars you won't ever make up the difference in efficiency gains.

I could go on for 20 min about the disadvantages of 120V charging but the biggest issue is safety and that is another long topic. 120V charging is inherently an unsafe method because of the constant load on an outlet and circuit that is generally compromised. 120V use should be relegated at home to a dedicated 20A circuit with a new and high-quality outlet, if you have that then it makes more sense to convert it to a 240V 20A 6-20. Don't use 120V particularly since you don't need to.

Assuming you have a properly wired outlet, 120V isn't inherently unsafe. With 12ga wiring and a 20A breaker backing it, you should be fine pulling 12A out of a multi-ganged outlet. If your concern is that it could be connected to 100 things in the house... well, that's a separate problem. I personally would see no issues with a 20A breaker servicing an entire garage (multiple outlets) being used to charge a Tesla at 12A. Hell, if you don't have a fridge or some other relatively high current draw device that is going to suck a bunch of power, you could charge at 16A. There's a reason for that 80% derating...

 

[eprosenx]

My solar system will be sized large, so I'll have plenty of power, and the utility will not buy my excess, so efficiency is a moot point. My only concern is what's best for the car (and the house -- thanks to those who mentioned possible strain on the circuit).

Do you need to utilize the power at the exact time it is generated (i.e. "no export" to the grid allowed), or does the power company let you export power during the sunny times and then pull it back later at a 1:1 trade, so while they won't "pay" you for overages, they allow you to time shift using the grid as a battery? I ask because if you need to utilize the power at the instant it is generated then you may want larger charging ability so you can have the car charge at just the right time of day. (are you going to have storage like Tesla Powerwall's or something?)

Assuming you have a properly wired outlet, 120V isn't inherently unsafe. With 12ga wiring and a 20A breaker backing it, you should be fine pulling 12A out of a multi-ganged outlet. If your concern is that it could be connected to 100 things in the house... well, that's a separate problem. I personally would see no issues with a 20A breaker servicing an entire garage (multiple outlets) being used to charge a Tesla at 12A. Hell, if you don't have a fridge or some other relatively high current draw device that is going to suck a bunch of power, you could charge at 16A. There's a reason for that 80% derating...

This is a good callout. Assuming that the circuit is 20a with 12 gauge wire (this is not a given - I have seen a lot of houses with 15a circuits in the garage as I don't know that 20a is a requirement) then if you are just using the NEMA 5-15 adapter (likely because the receptacles are not even 5-20 capable even if the circuit is) then you still have 5a (4a continuous) of available headroom for "other" stuff.

I would say though that if you are charging at 16a continuous (using a 5-20 adapter) then that circuit is *100%* utilized. It is not that you still have 4a remaining for other stuff. That capacity is burned by the continuous load nature of the EV. So in the example of drawing 12a on the 20a circuit above, that 12a counts as 15a. So you have 5a remaining (or only 4a if you want to connect another "continuous" load).

 

[MountainRatMat]

120V charging is not as efficient as 240V charging, there are more losses. That being said, you are on solar so not sure if losses matter much to you.

 

[Brass Guy]

At the same current, 240V charges nearly 3x faster than 120V; due to static overhead as pointed out by @SSedan above. Off the top of my head, this brings up 2 issues.
1) 120V is much less efficient. Even if you don't need to charge faster, if you have any aversion to waste then avoid it. (I hate unreasonable waste.)
2) Your car's on-board charger (and other vehicle systems that would otherwise be idle) will be in use 3x longer; tripling wear. In the short-term, this wouldn't be an issue; but over years of this kind of use, that wear will add up.

 

[Galve2000]

if u can really get by with 120 V i would save the money on the install of 240 V.. but EVs are here to stay.. u may as well future proof yr home/biz and install a 240 V line.. it will pay for itself in the long run.