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What amperage do I set for dryer plug?

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Hi everyone,

I’m using the dryer plug to charge my Model 3 RWD now. Coming in at night, I usually have 30-40% battery left and it stays parked for 12 hours. The default amperage right now is at 24 which nets me 38 kilometres an hour. Would it be a good idea to manually decrease the amperage to 15-20 since I’ll have a full charge with that anyways? I’m assuming there will be less heat and whatnot, too? Any tips?
 
Charging at higher amperages is more efficient than charging at lower amperages as there is overhead in charging. 220/240V is also more efficient than 110 for the same reason. I would charge at the highest rate supported by the wiring and breaker- if you're seeing excess heat that concerns you, then either check your wiring and/or reduce the charge rate.
 
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I don't charge at home myself, but here's how I see it:

You can lower your charging amperage in order to complete your charge about the time you would normally leave the house. That would put a bit less strain on your wiring but at the very slight cost of increasing the amount of power it take to charge. The reason? There's a fixed amount of power that goes into the car that is not directed into your main battery. Lowering the "speed" of your charge means more time is spent keeping the car's computers running rather than putting energy back into the battery.

By leaving the default amps to 24A, which implies that you are connecting to a 30A outlet (6-30, 10-30, or 14-30), you would be charging the car the fastest and thus minimizing the power "wasted". Yes, that could mean a slightly more warmer wiring but if you take the time and inspect the socket and wiring to make sure it's not getting hot, then that should be no problem. While you're at it, check to see what size wire is being used for that outlet. 30A should be provisioned with at least 10AWG copper; 8 would be better. Also I would check to see what brand of outlet you have. Residential ones are cheaper than commercial or industrial versions but you get what you pay for. If this dryer outlet was installed when the house was built, I would look into swapping it out for a better one as soon as possible. Charging a car can be much harder on the wiring/socket than running a dryer for a couple of hours.

Also, if you have a time-of-use electricity plan, you may want to make sure that you are charging at the lowest cost time of day. Check your rate plan for details. Going to a lower amperage will increase the time needed to fully charge and that may put you into a higher cost electrical rate.
 
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I don't charge at home myself, but here's how I see it:

You can lower your charging amperage in order to complete your charge about the time you would normally leave the house. That would put a bit less strain on your wiring but at the very slight cost of increasing the amount of power it take to charge. The reason? There's a fixed amount of power that goes into the car that is not directed into your main battery. Lowering the "speed" of your charge means more time is spent keeping the car's computers running rather than putting energy back into the battery.

By leaving the default amps to 24A, which implies that you are connecting to a 30A outlet (6-30, 10-30, or 14-30), you would be charging the car the fastest and thus minimizing the power "wasted". Yes, that could mean a slightly more warmer wiring but if you take the time and inspect the socket and wiring to make sure it's not getting hot, then that should be no problem. While you're at it, check to see what size wire is being used for that outlet. 30A should be provisioned with at least 10AWG copper; 8 would be better. Also I would check to see what brand of outlet you have. Residential ones are cheaper than commercial or industrial versions but you get what you pay for. If this dryer outlet was installed when the house was built, I would look into swapping it out for a better one as soon as possible. Charging a car can be much harder on the wiring/socket than running a dryer for a couple of hours.

Also, if you have a time-of-use electricity plan, you may want to make sure that you are charging at the lowest cost time of day. Check your rate plan for details. Going to a lower amperage will increase the time needed to fully charge and that may put you into a higher cost electrical rate.

Just the answer I was hoping to look for. Thanks, man. I’m going to keep it at 15A for tonight and slowly increase it when I charge it next just to be safe. Seems like the rates are cheapest in between 11PM and 7AM. Car should be charged by then. I am planning on moving by the end of this year so don’t really want to install a dedicated wall charger yet but I’ll have an electrician swing by to make sure everything is OK.
 
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Charging at higher amperages is more efficient than charging at lower amperages as there is overhead in charging. 220/240V is also more efficient than 110 for the same reason. I would charge at the highest rate supported by the wiring and breaker- if you're seeing excess heat that concerns you, then either check your wiring and/or reduce the charge rate.

For now I will keep it at 15A and increase it the next time I charge it just to be safe. My dryer has been running on 30A for ages so I think I’m OK but I still want to be absolute certain that my house won’t burn down overnight, haha.
 
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Hi everyone,

I’m using the dryer plug to charge my Model 3 RWD now. Coming in at night, I usually have 30-40% battery left and it stays parked for 12 hours. The default amperage right now is at 24 which nets me 38 kilometres an hour. Would it be a good idea to manually decrease the amperage to 15-20 since I’ll have a full charge with that anyways? I’m assuming there will be less heat and whatnot, too? Any tips?
funny enough im using my 10-30 dryer socket too haha,
its rated for 240v 30A but the safety in the charger limits it to 24A

honestly, i dont see the problem with ether method,
faster charge or slower charge,
unless your wires are super old like in my home reduce the stress on the circuit
the rate of $ you pay for should be the same ether way
(sadly in my case, its actually cheaper to supercharge at 0.24c / kwh than do it at home...)

and really, anything under supercharger levels of amps is "Slow" charging as far as that battery is concerned
 
When a dryer is first turned on it may draw ~23 amps, but when it heats up after a while the thermostat will turn off the heating element and the only load will be the motor and the control electronics or timer motor, just a few amps. It will then cycle the heating element on and off until it is finished. Thus it is not a continuous load.

A dryer outlet, and 10 g CU wire should have no problem delivering 24 amps continuous. If you are worried, check to be sure the plug and circuit breaker are not getting hot. A little warm is OK. Make sure the wires at the breaker and dryer receptacle are tight. If the receptacle is old, replace it with a new one. A loose wire, or a receptacle with worn contacts can and likely will burn up.

On a Tesla (or other brand)wall charger, with a 60 amp breaker and at least 6 g CU wire, 48 amps, about 11.2 KW at 240 volts is a lot of power for most houses. In most houses nothing comes close, unless it has electric heat. Most ranges, ovens, cooktops, dryers all draw close to 5 to 7 kW, but the draw is intermittent, as is usually electric heat (but not always it -- it can stay on for hours in very cold weather). 48 amps for 2 to 6 hours is a whole other animal. Most houses with 200 amp services can handle this unless they are loaded with electric heat. Again, make sure all the connections are tight. If using the full capacity of 48 amps I recommend charging overnight which will put less stress on your house wiring, the outside wire and transformer outside feeding your house, and the entire grid in general.