5-20 charging speed

[alekaras]

I'm moving to a new townhouse that has the crappiest electric lines and will not support a 240V outlet. So I'm stuck with a 5-20. I know the Tesla site says 4 miles/hr charging rate, but is there anyone using it that is getting different numbers?

 

[Sophias_dad]

6mi/hr, I believe. 16 amps times 120V is 1920W, divided by 270 is 7.11mi/hr. But you gotta take a decent amount away for charger inefficiency and keeping the car awake.

 

[jcanoe]

Charging using the 5-20 plug adapter and the Gen2 Mobile Connector should enable you to charge at 6 miles of range added per hour of charging. Tesla's Gen2 plug adapter table shows 4 MPH. The referenced video (a few posts down) shows that Tesla does support charging at 120V and 16A when using the 5-20 plug adapter. I have used the 6-20 (240V and 16A) charging setup and that was able to add 12 miles per hour so 6 miles per hour using the 120V/16A should be possible. If Tesla assumes you drive at 75 MPH instead of a more leisurely pace then 4 miles per hour of charging when using the 5-20 adapter would be a better estimate than 6 miles per hour when charging using the 5-20 adapter.

Gen 2 NEMA Adapters

 

[Stavinski]

I’ve never seen better than 4 personally, but lowest the car has been is ~40% battery. Don’t go that far on a daily basis.

 

[ATPMSD]

As you have a 5-20 outlet you might be able to upgrade to 240V using the existing wires, this should increase your charing speed by about 3.5x

Here is how to do this:
1. First you need to ensure you are using a dedicated circuit. If the circuit serves any other outlets or lights you need to disable them.
2. Replace the single pole 20A breaker with a dual-pole 20A breaker. This means you will need two open slots side by side.
3. Wire the black wire to one breaker and the white to the other, leave the ground connected
4. Replace the 5-20 (120V) outlet with a 6-20 (240V) outlet
5. Buy a 6-20 adapter from Tesla

 

[jcanoe]

I’ve never seen better than 4 personally, but lowest the car has been is ~40% battery. Don’t go that far on a daily basis.

When I would charge my 2017 Chevy Volt using the 5-15 and the default 8 amp setting this would consistently yield 2.7 miles per hour of charging. When charging at 120V and the optional 12 amp setting this was good for a little over 4 miles per hour of charging.

If you view the Tesla's Charging screen while charging using the Gen2 Mobile Connector and the 5-20 plug adapter this will display the charging rate (rounded up to the nearest kW.) If the Tesla is able to charge at 120V and 16 amps using the 5-20 plug adapter the charging screen should show the charging rate as being 2kW.

 

[angus[Y]oung]

@alekaras coincidentally I ran across this video earlier today when someone linked another video from the same YouTuber. You might find it informative:

 

[alekaras]

Charging using the 5-20 plug adapter and the Gen2 Mobile Connector should enable you to charge at 6 miles of range added per hour of charging. Tesla's Gen2 plug adapter table shows 4 MPH. The referenced video (a few posts down) shows that Tesla does support charging at 120V and 16A when using the 5-20 plug adapter. I have used the 6-20 (240V and 16A) charging setup and that was able to add 12 miles per hour so 6 miles per hour using the 120V/16A should be possible. If Tesla assumes you drive at 75 MPH instead of a more leisurely pace then 4 miles per hour of charging when using the 5-20 adapter would be a better estimate than 6 miles per hour when charging using the 5-20 adapter.

Gen 2 NEMA Adapters

Thanks @jcanoe I found the comment about how fast I drive intriguing. How would that affect charging?

 

[jcanoe]

Thanks @jcanoe I found the comment about how fast I drive intriguing. How would that affect charging?

Only that the charging rate is determined by the circuit and is fixed. When you charge from a standard 120V receptacle the maximum charging rate is a bit over 1kW accounting for voltage variations and charging losses. Some drivers can exceed 4 miles of range using 1kWh of battery. Others barely see 3 miles of range for the same 1kWh. The main difference in driving is related to average speed. Driving faster uses more energy, lowers your miles per kWh estimate. Driving slower increases your miles per kWh estimate.

It is the same with a gas vehicle. Some drivers can achieve 30 MPG, others can only get 26 MPG for the same vehicle, engine and options. The gas vehicle can be fully fueled up in minutes. An EV takes many more minutes (when using a Supercharger) or many more hours when charging using a 120V or 240 receptacle. It is important for planning purposes when charging at home to understand how many hours it will take so that you can drive Xx miles on your daily drive. This is really more of an issue when charging from a 120V receptacle since charging at 120V results in either 3 miles per hour or 4 miles per hour depending on how fast, how efficiently you drive (or if you use the heat in winter.) You may come up short if you need 11 hours or more to charge for your daily driving needs but only realistically have 9 or 10 hours available to charge before you have to drive. When you charge using 240V charging is fast enough that the total time needed to charge will not limit your driving range.

 

[alekaras]

Only that the charging rate is determined by the circuit and is fixed. When you charge from a standard 120V receptacle the maximum charging rate is a bit over 1kW accounting for voltage variations and charging losses. Some drivers can exceed 4 miles of range using 1kWh of battery. Others barely see 3 miles of range for the same 1kWh. The main difference in driving is related to average speed. Driving faster uses more energy, lowers your miles per kWh estimate. Driving slower increases your miles per kWh estimate.

It is the same with a gas vehicle. Some drivers can achieve 30 MPG, others can only get 26 MPG for the same vehicle, engine and options. The gas vehicle can be fully fueled up in minutes. An EV takes many more minutes (when using a Supercharger) or many more hours when charging using a 120V or 240 receptacle. It is important for planning purposes when charging at home to understand how many hours it will take so that you can drive Xx miles on your daily drive. This is really more of an issue when charging from a 120V receptacle since charging at 120V results in either 3 miles per hour or 4 miles per hour depending on how fast, how efficiently you drive (or if you use the heat in winter.) You may come up short if you need 11 hours or more to charge for your daily driving needs but only realistically have 9 or 10 hours available to charge before you have to drive. When you charge using 240V charging is fast enough that the total time needed to charge will not limit your driving range.

Thanks. I also saw the video @srlawren posted and it all came together. Great analysis from both!

 

[Rocky_H]

As you have a 5-20 outlet you might be able to upgrade to 240V using the existing wires, this should increase your charing speed by about 3.5x

Here is how to do this:
1. First you need to ensure you are using a dedicated circuit. If the circuit serves any other outlets or lights you need to disable them.
2. Replace the single pole 20A breaker with a dual-pole 20A breaker. This means you will need two open slots side by side.
3. Wire the black wire to one breaker and the white to the other, leave the ground connected
4. Replace the 5-20 (120V) outlet with a 6-20 (240V) outlet
5. Buy a 6-20 adapter from Tesla

You did leave out one step in doing this. A white colored wire has to be on neutral unless it is marked differently. So if you are moving it to be a "hot" wire on one side of a 240V circuit, the white wire does need to be marked on both ends, either with like a black permanent marker or with electrical tape around it.

 

[ATPMSD]

You did leave out one step in doing this. A white colored wire has to be on neutral unless it is marked differently. So if you are moving it to be a "hot" wire on one side of a 240V circuit, the white wire does need to be marked on both ends, either with like a black permanent marker or with electrical tape around it.

Sounds like a good idea! But if you are going to do this I think it should be marked Red as the other wire is already Black. Black and Red are the common colors for 240V.

 

[TomServo]

I'll be charging on a 5-20 outlet at my kid's home when we visit next month, I bought the 5-20 pigtail from Tesla, is it Plug and Play, or do I need to adjust the amp setting?

 

[jcanoe]

I'll be charging on a 5-20 outlet at my kid's home when we visit next month, I bought the 5-20 pigtail from Tesla, is it Plug and Play, or do I need to adjust the amp setting?

Plug and Play; When the 5-20 power plug adapter is connected to the Gen2 Mobile Connector the maximum charging amperage is automatically set to 16A. You can lower the amperage from the Tesla Model Y's Charging screen if desired but you don't need to take any action.

 

[MN-MS100D]

Oh boy. Here we go. Clickbait video showing how easy it is to charge faster by simply buying a 20 amp adapter. No one knows what size wiring is buried in the wall, nor how many other outlets (or light fixtures if an older house) are on the same circuit. Yes, no one knows how much other stuff is on a 15 amp outlet, but this is more dangerous than less dangerous. Breakers do not always trip.

 

[Darblish]

Oh boy. Here we go. Clickbait video showing how easy it is to charge faster by simply buying a 20 amp adapter. No one knows what size wiring is buried in the wall, nor how many other outlets (or light fixtures if an older house) are on the same circuit. Yes, no one knows how much other stuff is on a 15 amp outlet, but this is more dangerous than less dangerous. Breakers do not always trip.

If you’re at some random outlet at a rental house somewhere, then no, you don’t know much about the circuit breaker, or whether someone slapped a 5-20R onto 14 gauge wire for whatever reason. However, if you’re in relatively new construction (which is more likely — but still not guaranteed — to meet code) or you’re in a position to check the wiring/breaker configuration to ensure it’s correct for a 20-amp outlet, I fail to see the impending doom in using the 5-20 adapter when it’s possible.

 

[MN-MS100D]

Of course I do not have a problem with a 20 amp device that draws 16 continuous amps on a dedicated 20 amp circuit. The problem is that no one knows where these dedicated circuits are. Even in your own house, unless you are electrically savvy. Most HO aren't. And you are correct, random 20A outlets in the wild are surely unknown.

Another problem I have is that people think that a $5 circuit breaker is a perfect device that will save them from bad decisions.

 

[TomServo]

Plug and Play; When the 5-20 power plug adapter is connected to the Gen2 Mobile Connector the maximum charging amperage is automatically set to 16A. You can lower the amperage from the Tesla Model Y's Charging screen if desired but you don't need to take any action.

Thanks, we have owned 3 Volts since March 2012 and charged them off a 5-15 outlet for 5 years before we had a lvl 2 EVSE installed and learned all about using these outlets safely from Volt owners.

My SIL confirmed there is NOTHING else on that circuit and he even pulled off the face plate and looked at how it was wired. The wires were attached to the screws not the STAB holes. But he wants to change it out with a new one. So we are confident in its safety, but we’ll monitor breaker and outlet temps (he has a handheld temp reader) and if necessary I’ll lower the amps, and we won’t charge over night just to be safe. But they just opened a new V3 SuperCharger 24 miles from their home should I need a quick top off to get from southern MD back out to I-64 so we can head home.

 

[Twiglett]

Thanks @jcanoe I found the comment about how fast I drive intriguing. How would that affect charging?

Its a bit like you don't buy 200 miles of gas, you pay by the gallon and use your average mpg to figure out how far you can drive.
Same with electricity except its measured in watts (or kilowatts) not gallons.
So, you add kilowatts of power by charging the battery and then use your average watts per mile to convert it to range.
They just use mph in this case to mean "miles of range gained per hour of charging".

 

[Sophias_dad]

My SIL confirmed there is NOTHING else on that circuit and he even pulled off the face plate and looked at how it was wired. The wires were attached to the screws not the STAB holes. But he wants to change it out with a new one. So we are confident in its safety, but we’ll monitor breaker and outlet temps (he has a handheld temp reader) and if necessary I’ll lower the amps, and we won’t charge over night just to be safe. But they just opened a new V3 SuperCharger 24 miles from their home should I need a quick top off to get from southern MD back out to I-64 so we can head home.

Make sure you verify its 12 gauge wire and a 20 amp breaker. (Technically a 15 amp breaker will supply 16 amps for a good while before tripping, but you really don't want to run it like that for real.)