Max charging rate for 50A 240v w/nema 14-50?

[Siciliano]

Hi guys, my electrician just got done wiring a 50A 240v connection to my garage, where he installed a 100A subpanel and then wired a 14-50 outlet off of it.

It looks like my charge is maxing out at 32A and 30 mi/hr, which is great, but I'm reading that some people with the same setup are getting 35+ mi/hr. Is that only possible with the Tesla wall charger, or is a 50A 240v connection capable of charge rates over 30 mi/hr??

Maybe I read wrong...I just want to be sure I'm getting the highest rate of charge possible after spending all that money on the L2 charging!


TIA!

 

[AlanSubie4Life]

Hi guys, my electrician just got done wiring a 50A 240v connection to my garage, where he installed a 100A subpanel and then wired a 14-50 outlet off of it.

It looks like my charge is maxing out at 32A and 30 mi/hr, which is great, but I'm reading that some people with the same setup are getting 35+ mi/hr. Is that only possible with the Tesla wall charger, or is a 50A 240v connection capable of charge rates over 30 mi/hr??

Maybe I read wrong...I just want to be sure I'm getting the highest rate of charge possible after spending all that money on the L2 charging!


TIA!

You have an SR+ (edit: this is false, but it wasn’t specified so it was possible).

240V*32A*0.88/ (60.5kWh/272rmi) = 30.4rmi/hr

Story checks out. Max rate for SR+ is 32A.

88% efficiency (might be slightly higher and when capacity loss occurs below the degradation threshold of 60.5kWh you could see an increase in charge rate (in rmi/hr) of 1-2% or so, because the rated miles are smaller then, but would be basically impossible to detect since resolution is about 2-3%, and of course the charge rate would be the same kWh/hr).

 

[jjrandorin]

Trying to decipher what you are asking here... I will lay out some facts and hopefully one of them addresses your question.

1. Tesla gen 2 mobile connectors (gen 2 is any mobile connector that would have come with a model 3) max charging rate is 32amps, regardless of which tesla you plug it into.

2. Tesla model 3 RWD or SR+ max out at 32amps charging rate.

3. No one charging with the tesla mobile connector (gen 2) is charging at 40amps (which shows on teslas website as 35mph).

4. To charge faster than 32 amps with tesla equipment, you need to both have a tesla that can charge faster than that ( AWD / P ) and also have a tesla wall connector, perhaps with a 14-50 adapter put on there by someone since tesla doesnt sell them that way any more.

 

[Siciliano]

You have an SR+

240V*32A*0.88/ (60.5kWh/272rmi) = 30.4rmi/hr

Story checks out. Max rate for SR+ is 32A.

88% efficiency.

No I have a dual motor non-performance. Is it different max charging rates between models?

 

[jjrandorin]

No I have a dual motor non-performance. Is it different max charging rates between models?

Between SR+ RWD and / P AWD, but I was going to say that I thought you had a AWD. So, point #1 I made is the one that addresses your question.

 

[AlanSubie4Life]

No I have a dual motor non-performance. Is it different max charging rates between models?

Whoops, failed to note you are using the outlet (14-50).

UMC limits it to 32A.

Anyway redoing the math, not that it is relevant:

32A*240V*0.88/(79kWh/358rmi) = 30.6rmi/hr.

You are 1 off, but it is possible (likely) your pack is above 79kWh, and loaded you are not likely seeing 240V at the car, of course.

So that’ll bump you down to 30.

 

[Siciliano]

Trying to decipher what you are asking here... I will lay out some facts and hopefully one of them addresses your question.

1. Tesla gen 2 mobile connectors (gen 2 is any mobile connector that would have come with a model 3) max charging rate is 32amps, regardless of which tesla you plug it into.

2. Tesla model 3 RWD or SR+ max out at 32amps charging rate.

3. No one charging with the tesla mobile connector (gen 2) is charging at 40amps (which shows on teslas website as 35mph).

4. To charge faster than 32 amps with tesla equipment, you need to both have a tesla that can charge faster than that ( AWD / P ) and also have a tesla wall connector, perhaps with a 14-50 adapter put on there by someone since tesla doesnt sell them that way any more.

I have an AWD, dual motor. My electrician installed the 14-50 in my garage...it's off of a 100A subpanel. I'm clueless with the electrician stuff...

 

[AlanSubie4Life]

Is it different max charging rates between models?

In general yes, for a given charging setup. On your car it is 30rmi/hr but on my 2018 it is 27.5mi/hr at 32A.

But it is all the same of course. It is all 7.7kW into the vehicle. Just different rates because the units of energy (miles) are different.

My miles are bigger than yours (unfortunately for me).

If you want higher rates the highest you can get is 40A with that (assumed 50A) breaker, and you’d need a wall connector or some other (plugged in) EVSE capable of higher current.

There’s likely going to be only a few times (accidents where you forget to charge the car) where you’ll want higher rates.

The max you’ll see reported with the 32A UMC will be about 33mi/hr for the last SR+ with NCA (53.5kWh, 263rmi). Could bump up slightly higher possibly if efficiency is 90%.

That’s exactly the same rate though. 7.7kW. It’s all the same. Efficiency is very similar between models.

Just use the formulas; they are very deterministic (but you have to know the pack size - but that is pretty easy to get close - at least getting the degradation threshold is easy and gets you close).

Your pack is almost certainly greater than 79kWh right now, to be clear.

If you found a way to charge at 40A, you’d get around 38rmi/hr. The max for your vehicle is 48A, about 46mi/hr (for your vehicle - for mine it is about 41mi/hr, which is the same, of course).

 

[E90alex]

If you are using the universal mobile connector then that maxes out at 32A

 

[jjrandorin]

I have an AWD, dual motor. My electrician installed the 14-50 in my garage...it's off of a 100A subpanel. I'm clueless with the electrician stuff...

Since you quoted my post, I will highlight the part of it that is relevant to you (that others have also pointed out):

1. Tesla gen 2 mobile connectors (gen 2 is any mobile connector that would have come with a model 3) max charging rate is 32amps, regardless of which tesla you plug it into.

 

[gearchruncher]

and also have a tesla wall connector, perhaps with a 14-50 adapter put on there by someone since tesla doesnt sell them that way any more.

The older UMC's could do 40A, and there are J1772's that can do 40A. So it is possible to get 40A from a 14-50 without a wall connector if a Tesla owner wants to. (I agree the 32A limit here is the UMC included with the Model 3, just pointing it out in case the OP wants to charge faster off the outlet they have)

 

[jjrandorin]

The older UMC's could do 40A, and there are J1772's that can do 40A. So it is possible to get 40A from a 14-50 without a wall connector if a Tesla owner wants to. (I agree the 32A limit here is the UMC included with the Model 3, just pointing it out in case the OP wants to charge faster off the outlet they have)

Yeah, I was trying to summarize in point 4 of my first post and said "with tesla equipment" but didnt get specific enough, there.

 

[Siciliano]

Thanks guys! I probably should have worded it differently, something like: "is anyone getting anything over 30 mi/hr with a 50a 240v connection plugged into a 14-50 outlet?"

I just paid $1400 for the job, but he had to run 90 feet of cable from my main panel, and that includes installing the sub panel and 14-50 outlet in the garage. After spending that amount of money I just want to make sure I'm getting the fastest rate of charge.

 

[gearchruncher]

Thanks guys! I probably should have worded it differently, something like: "is anyone getting anything over 30 mi/hr with a 50a 240v connection plugged into a 14-50 outlet?"

The answer is yes, but not using the charge cord (UMC) that comes with a Tesla Model 3. You need some different charging equipment to get the last 8 amps.

You will never get above 40 because the electric code prohibits using more than 80% of an outlet's rating when used for "continuous use" which EV charging counts as. So 0.8 * 50 = 40A.

If you hard wire a wall charger, the car can charge at 48A.

As an FYI, it's worth plugging the car into a >32A charger now and then. There are failures in the car where it can only charge at a max of 32A, and Tesla will cover that repair in the first 4 years of warranty, but not after.

 

[AlanSubie4Life]

is anyone getting anything over 30 mi/hr with a [32A UMC at] 240v connection plugged into a 14-50 outlet

Note my modifications. And the answer to this is yes, as well. You’ll see people report 33mi/hr or so.

But that is exactly the same as your 30mi/hr! (They have a different car; SR+ NCA specifically.)

Your car can max out at about 46mi/hr with an appropriate setup. (Mine is ~41mi/hr for reference, which is also the same 11.5kW.)

The 40A option available to you above (with appropriate equipment you don’t currently have) will give about 38mi/hr. That is the absolute max possible from a 14-50 (and likely the max you will see reported for now until a more efficient LR appears, since SR+ cannot charge at that rate).

There was someone who reported they got a 48A PCS (AC-DC converter) installed in their SR+ by mistake when their PCS failed - they’d see higher of course; about 49 or 50mi/hr at 48A, 42mi/hr at 40A. Special case though! And the same.

 

[Tronguy]

@Siciliano:

Let's take this from the top, so it's clear.

When you're charging an EV, everything has a limit.

1. The car itself has a limit: SR/SR+ has a max 208/240 VAC current of 32A.
2. With a Tesla, you've got a choice: A Mobile Connector (that's the thing in the trunk) or a Wall Connector.
   1. Mobile Connector: Right off, these don't do more than 32A, never mind the voltage. Period. Mobile Connectors have adapters (see the link to the left to Tesla). Adapters hook up to NEMA connectors. Rule: Whatever the current rating is on the NEMA connector, one is not supposed to run more than 80% of that, steady state, by the National Electric Code.
      1. NEMA5-15: Standard 120 VAC wall socket adapter. The NEMA5-15 socket is rated for 15A, but, because of the NEC, the Mobile Connector/car will enforce a limit of 80% of 15A, or 12A.
      2. NEMA14-50: 240 VAC, 50A adapter. Maximum current is theoretically 80% of 50A, or 40A: But see the comment about the Mobile Connector not doing more than 32A (the 32A wins).
      3. NEMA14-30: 240vac, 30A adapter. Maximum current, enforced by the car/Mobile Connector, is 80% of that, or 24A. By now you should be getting the idea.
   2. Wall Connectors. These, by the name, hang on the wall and have a Tesla cable attached. There are some variations, but these babies are designed to be hard-wired into the breaker panel. A Generation 2 WC (I happen to have one) can be set to deliver 100A; there are certain old Model S's that can accept that. The general rule: One sets the rotary switches (Gen 2) or uses a web browser (Gen 3) to set the max current to 80% of the wire/breaker provided. Example: My place. I got a 60A 240 VAC breaker with some seriously hefty wire connected to a Gen 2 WC. The Gen 2 is set to 48A (80% of 60A. Again with the 80% rule.)
   3. Wall Connector, Take 2: Tesla has a Wall Connector with the Tesla Cable/connector on the end. There are an infinite number of other vendors of Wall Connectors, mostly with J1772 cables. Each one of those Wall Connectors has (a) an internal limit and (b) a limit set by the wire going to the breaker panel and the size of the breaker in the panel.
3. Breaker Panel/Wire/Socket: If one has a NEMA14-50 on the wall, then there had better be (NEC, again) wire rated for 50A and a breaker rated at 50A and no more or less. Anything else attracts the negative attention of the electrical building inspector. If one has a NEMA14-30, then the wire can be rated for something more than 30A, say, but the breaker had better be equal to 30A to match the socket. Period.
4. Load Calculation. You've had a no-kidding electrician come on down, look over your setup, put in a sub-panel, that 50A breaker, the wire for it, and presumably a socket also rated for 50A. Licensed electricians are careful to make sure that when a reasonable number of loads are active, the Main Breaker (sub panel, or the main back on the main breaker panel for the house) doesn't trip. You shouldn't have to worry about that.

The whole point: "How much current can I stuff into my car?" Answer: The Lowest Limit Wins.

Car: If it's an SR/SR+, you get 32A, max. That's all the car will do. You can do less than that. If you got a LR or P, the car can do 48A.

Mobile Connector: The body of the thing limits to 32A.

Mobile Connector adapter: Depends upon the adapter. NEMA14-50 gets you 32A, but that's the MC itself doing that. NEMA14-30, it's 80% of 30A, or 24A. And so on. See the listing at the Tesla link, above.

Wall Connector: Gen 3 WC's can do up to 48A, but only if they're hooked to a 60A circuit. If you've got one hard-wired to a 50A circuit, then 80% of 50A=40A is all you're going to get, max. If you're using somebody else's WC, the majority of those (that are less expensive than a Gen 3 WC) do 32A max; there are pretty expensive ones that can do more than 48A, but they require a wire/breaker combo that can do 60A or more. And modern Teslas don't go higher than 48A, anyway.

Like I said: The lowest maximum wins.

Now, we've had people come by here with WC's with the incorrect settings, high or low, and set them straight. But it sounds like you're running with a Mobile Connector. Is that the case?

 

[Siciliano]

Note my modifications. And the answer to this is yes, as well. You’ll see people report 33mi/hr or so.

But that is exactly the same as your 30mi/hr! (They have a different car; SR+ NCA specifically.)

Your car can max out at about 46mi/hr with an appropriate setup. (Mine is ~41mi/hr for reference, which is also the same 11.5kW.)

The 40A option available to you above (with appropriate equipment you don’t currently have) will give about 38mi/hr. That is the absolute max possible from a 14-50 (and likely the max you will see reported for now until a more efficient LR appears, since SR+ cannot charge at that rate).

There was someone who reported they got a 48A PCS (AC-DC converter) installed in their SR+ by mistake when their PCS failed - they’d see higher of course; about 49 or 50mi/hr at 48A, 42mi/hr at 40A. Special case though! And the same.

If you don't mind me asking, how are you getting 41 mi/hr? And how would I max out at 46? Is the hardwired wall connector required in these cases?

 

[AlanSubie4Life]

If you don't mind me asking, how are you getting 41 mi/hr? And how would I max out at 46? Is the hardwired wall connector required in these cases?

As I said, that would require a 48A continuous circuit, so at least a 60A breaker (there are options to do 80A charging off of a 100A breaker through the Tesla Wall Connector but not for our cars, which max out at 48A, 240V, 11.5kW!).

Anyway. That would require a hard-wired WC or some other EVSE which could deliver 48A. And a breaker of at least 60A. I have a 40A setup at home, just like you but with a WC, but I have a friend with an 80A Wall Connector (where I can get 48A).

Ignore the mi/hr here - they are just approximate - looks like it is right at 32A but it is probably going to be higher than 44mi/hr at 48A. Close enough though.

 

[AlanSubie4Life]

If one has a NEMA14-50 on the wall, then there had better be (NEC, again) wire rated for 50A and a breaker rated at 50A and no more or less.

Annoyingly, I think a 40A breaker AND wiring (?) is allowed for a 14-50 receptacle, since there is no NEMA 40A receptacle. One of the reasons the UMC is limited to 32A now probably! Someone can correct me if I am wrong. Side conversation though, irrelevant here.

 

[Tronguy]

If you don't mind me asking, how are you getting 41 mi/hr? And how would I max out at 46? Is the hardwired wall connector required in these cases?

Check out this link, straight to Tesla's page on the Mobile Connector and its adapters. There are charts there that clearly say how many Miles of Charge per Hour one is going to get with what adapter. One can reverse engineer the calculations, knowing the wattage being delivered, the car's efficiency rating (W-hr/mile), and some guess-and-by-golly about how much energy is lost going through the charging system, but what the heck.

Both a 3rd Quarter, 2018 Model 3 LR RWD and a 4th Quarter 2021 Model Y LR AWD, we get 45 to 47 Miles of Charge per Hour at 48A at 240 VAC.