110/120v Charging Amps Limits

[jcanoe]

I'm using the standard wall charger but I can only charge at 8A. When I plug it in, it automatically drops it to that level probably because I also have a freezer in my garage. The freezer is plugged into another outlet, but they are all on the "garage" circuit on my breaker.

So far, the 8A has met my needs, but I wish it was a little faster. (I'm currently only getting 2-3 mph).

How easy/costly would it be to get the outlet I'm currently using for the charger on its own 15A breaker so that I could draw 12A? I'm guessing the electrician would just need to install another switch on the panel and just move the wires to that outlet to the new switch?

There are many variables that will determine the cost of installing the new circuit. Where is the service panel located in relation to where you want to install the charging equipment? Most of the cost of installing an electrical circuit is in the labor so it makes sense to plan for your current and future needs.

To start, determine your needs. How many miles, per day, do you typically drive? (If the current 120V/8A charging is adequate then upgrading to 240V at any of the common 240 circuit ratings (20A, 30A, 40A, 50A, 60A) will be more than adequate.) A reason to install one of the lower amperage circuits is that your home's service is already nearly fully loaded. A reason to install one of the higher amperage circuits is you want to charge faster. If you have at least 6 hours, overnight, to charge the Tesla vehicle at home any of the 240V circuits will be able to meet your home charging needs.

Contact several electricians and request they review your home's electrical service and provide you with a price quotation.

 

[Wolfpacker83]

There are many variables that will determine the cost of installing the new circuit. Where is the service panel located in relation to where you want to install the charging equipment? Most of the cost of installing an electrical circuit is in the labor so it makes sense to plan for your current and future needs.

To start, determine your needs. How many miles, per day, do you typically drive? (If the current 120V/8A charging is adequate then upgrading to 240V at any of the common 240 circuit ratings (20A, 30A, 40A, 50A, 60A) will be more than adequate.) A reason to install one of the lower amperage circuits is that your home's service is already nearly fully loaded. A reason to install one of the higher amperage circuits is you want to charge faster. If you have at least 6 hours, overnight, to charge the Tesla vehicle at home any of the 240V circuits will be able to meet your home charging needs.

Contact several electricians and request they review your home's electrical service and provide you with a price quotation.

Sorry I wasn't clear. My garage has 5 outlets on the various walls. (110V) and they are all on a 15A breaker. I use one of the plugs for the Tesla (8A), one of the plugs has a freezer, and garage door is only other thing plugged in.

How easy would it be to put the outlet I'm using to charge on its own breaker? It would stay 110V but then I'd be able to charge at 12A since it isn't shared by anything else. So not putting in a new outlet, just changing it to its own breaker switch.

 

[jcanoe]

Sorry I wasn't clear. My garage has 5 outlets on the various walls. (110V) and they are all on a 15A breaker. I use one of the plugs for the Tesla (8A), one of the plugs has a freezer, and garage door is only other thing plugged in.

How easy would it be to put the outlet I'm using to charge on its own breaker? It would stay 110V but then I'd be able to charge at 12A since it isn't shared by anything else. So not putting in a new outlet, just changing it to its own breaker switch.

Sorry I wasn't clear either. Where is the circuit breaker panel located in your home? Is it in or close to the garage?

 

[Wolfpacker83]

Sorry I wasn't clear either. Where is the circuit breaker panel located in your home? Is it in or close to the garage?

Yes, the subpanel is directly in front of my car in the garage. Would it be as simple as unwiring that particular outlet from the breaker and just adding a new breaker for just that outlet?

 

[jcanoe]

When you add a new circuit there must be available capacity for the additional circuit load within the home's electrical service and also physical space in the panel or sub panel for the new circuit breaker. 240V circuits use a double pole circuit breaker, the sub panel probably has limited space for double pole breakers. If there is capacity and space then a new wire run will be needed from the sub panel to the location where you want to install the receptacle for charging (if you want to hard wire the charging equipment (as for the Tesla Wall Connector) then the wiring is simpler (one less wire, no receptacle is needed.) Also, a 240V/50A circuit with a 14-50 receptacle (very popular for charging at home) requires a GFCI circuit breaker (these cost about $100.)

 

[Wolfpacker83]

When you add a new circuit there must be available capacity for the additional circuit load within the home's electrical service and also physical space in the panel or sub panel for the new circuit breaker. 240V circuits use a double pole circuit breaker, the sub panel probably has limited space for double pole breakers. If there is capacity and space then a new wire run will be needed from the sub panel to the location where you want to install the receptacle for charging (if you want to hard wire the charging equipment (as for the Tesla Wall Connector) then the wiring is simpler (one less wire, no receptacle is needed.) Also, a 240V/50A circuit with a 14-50 receptacle (very popular for charging at home) requires a GFCI circuit breaker (these cost about $100.)

Not talking about a 240V circuit.
I just want one of my 110V outlets in my garage switched to its own dedicated breaker so that I can pull 12A on it instead of 8A.

 

[jcanoe]

Not talking about a 240V circuit.
I just want one of my 110V outlets in my garage switched to its own dedicated breaker so that I can pull 12A on it instead of 8A.

You can't just wave a wand so that one of the existing 120V (110V is old school speak) in your garage can enable you to charge at 12A instead of being limited to 8A. 12A EV charging on a 15A rated circuit is the maximum. You can only charge at 12A when nothing else is plugged into an outlet that is wired to the same circuit.

Your only option (unless you are prepared to unplug any other equipment that is powered by the circuit powering the other outlets) is to install a new circuit. This will require new wire to be pulled from the circuit breaker panel to where you want the new receptacle. (To an electrician a 120V circuit and a 240V circuit are practically the same amount of work. Only the circuit breaker and the receptacle is different when you install a 240V circuit. To you however, a 240V circuit means that for the same cost, circuit rating, i.e. 20A, you will benefit from being able to charge at twice the power, twice as fast and complete charging in half the time. 240V charging is so much of an improvement over 120V charging that once you experience it you won't ever want to charge at 120V. Ask an electrician about what would be required to install a 240V/20A circuit instead of a 120V/20A circuit.

 

[Wolfpacker83]

You can't just wave a wand so that one of the existing 120V (110V is old school speak) in your garage can enable you to charge at 12A instead of being limited to 8A. 12A EV charging on a 15A rated circuit is the maximum. You can only charge at 12A when nothing else is plugged into an outlet that is wired to the same circuit.

Your only option (unless you are prepared to unplug any other equipment that is powered by the circuit powering the other outlets) is to install a new circuit. This will require new wire to be pulled from the circuit breaker panel to where you want the new receptacle. (To an electrician a 120V circuit and a 240V circuit are practically the same amount of work. Only the circuit breaker and the receptacle is different when you install a 240V circuit. To you however, a 240V circuit means that for the same cost, circuit rating, i.e. 20A, you will benefit from being able to charge at twice the power, twice as fast and complete charging in half the time. 240V charging is so much of an improvement over 120V charging that once you experience it you won't ever want to charge at 120V. Ask an electrician about what would be required to install a 240V/20A circuit instead of a 120V/20A circuit.

I understand now. Thank you for the explanation.

 

[jcanoe]

One more benefit of 240V charging is that it is more efficient than charging at 120V; ~90% efficiency at 240V versus ~83% efficiency at 120V.

 

[dcantato]

I have a question that I hope doesn't sound daft - Recently I ordered the gen 2 UMC. I had been using a 120v charger (5-15 plug) that came with a previous car on an outlet when traveling and it would say I was charging at 12amps getting 4/5 miles per hour charged. The tesla site claims that their charger using the Gen 2 UMC would get 3 miles per hour with the 5-15 plug. Is that just their estimations being conservative and the translations between kwh to mph not being direct or is the charger slower than other chargers using 5-15?

 

[Mike728]

I have a question that I hope doesn't sound daft - Recently I ordered the gen 2 UMC. I had been using a 120v charger (5-15 plug) that came with a previous car on an outlet when traveling and it would say I was charging at 12amps getting 4/5 miles per hour charged. The tesla site claims that their charger using the Gen 2 UMC would get 3 miles per hour with the 5-15 plug. Is that just their estimations being conservative and the translations between kwh to mph not being direct or is the charger slower than other chargers using 5-15?

You should ignore the mph claims and just focus on the charge current. My gen 2 also charges at 12A, so no difference.

 

[Rocky_H]

The tesla site claims that their charger using the Gen 2 UMC would get 3 miles per hour with the 5-15 plug. Is that just their estimations being conservative and the translations between kwh to mph not being direct or is the charger slower than other chargers using 5-15?

It can't be any faster or slower since it's literally just closing a switch. It doesn't do any converting or "charging".

That 3 mph is because of a years old typo if you can believe it.

Waaaayyy back in 2012, when they first came out with their Model S, they made that web page, and it listed those charging speeds on them. The old original Model S was a big heavy pig and kind of inefficient, so that 3 mph was accurate. I have a 2014 Model S, and that's correct for mine. Well over the years, the S got more efficient motors, and especially when the 3 and Y came out, they were MUCH more efficient. Tesla edited the numbers in those charging speed tables for every single number except that one. They forgot to update that number to the 4 or 5 that it really is! So it has sat there with incorrect information for years.