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NEMA 10-30 Charging for the first time at home.

tm3p-fan

Member
Sep 19, 2019
76
20
FL
First time charging at home after buying this to hook up to my dryer outlet.

https://www.amazon.com/Parkworld-886580-Splitter-Receptacle-3-Prong/dp/B07CVSJ6S9

I purchased the 20ft cable.
Charge rate is 6kw at 240 24 amps.

Initially, I saw the flashing green light on the car indicating that the vehicle was being charged. After about 10 mins, the flashing stopped. Wtf. I checked the charger and the lights on the charger with the TESLA letters in sequential green was flashing and I noticed the % number increased...by 1, so I was kinda relieved.

Can anyone confirm that the following is the correct rate of charge? I typically use 270w per mile, so, 1000/270 =3.7 miles per kw. At 6kw/hr I'm charging at 3.7*6 which equates to approximately a 22mile charge rate per hour.

If I change to the NEMA 14-50, approximately what is the charge miles/hr. If I do that, all i would need to buy would be a Tesla 14-50 plus the parts for the changing of the electrical circuits at home, right? Can the Tesla cable & charger can still be used when using the 14-50?

I have the TM3P-.

Thanks all!!
 

srs5694

Active Member
Jan 15, 2019
1,079
1,242
Woonsocket, RI
For some reason, the Model 3 shows the blinking green Tesla logo when you begin to charge, but that stops after a while (a minute? Five minutes? I've never timed it). Thus, what you observed with the blinking logo is perfectly normal.

According to Tesla's Mobile Connector adapter's page, a NEMA 10-30 adapter should add 22 miles of range per hour on a Model 3, so it sounds like you're getting exactly what you should. You can also check your display for the kW charge rate, which should be ~5.76 kW (or 24A x 240v).

Switching from a NEMA 10-30 to a NEMA 14-50 would increase the amperage of the charge from 24 to 32. (Tesla's Gen2 Mobile Connector maxes out at 32A, even though a NEMA 14-50 can theoretically provide up to 40A sustained.) Thus, the charge rate would go from ~5.76 kW to ~7.68 kW, which would produce about 30 miles of range added per hour.

If you must split a dryer connector, a somewhat more convenient, and possibly safer, way to do it is to use a product called the Dryer Buddy. This is conceptually similar to the splitter you're using, but it includes electronics to enable smarter switching, so you're less likely to accidentally draw too much current from the circuit. Of course, if you're thinking of upgrading your existing circuit, you might instead consider adding an entirely new circuit, which will be more flexible and further reduce the risk of creating problems.
 

tm3p-fan

Member
Sep 19, 2019
76
20
FL
Thank you for your quick response srs5694.
Your insight is much appreciated.
I'm sure other readers will benefit from this.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
10,042
12,095
San Diego
Can anyone confirm that the following is the correct rate of charge? I typically use 270w per mile, so, 1000/270 =3.7 miles per kw. At 6kw/hr I'm charging at 3.7*6 which equates to approximately a 22mile charge rate per hour.

Coincidentally you ended up with the right number, but that's not quite how it works.

You're at 24A @ ~240V as discussed, so 5.76kW AC.

The Model 3 Performance adds rated miles at the rate of 245Wh (DC) per rated mile (245Wh/rmi). It's not related to your average trip efficiency. This constant is only valid for the AWD variants of Model 3. It is different for the other Model 3s. (Aside: Also note that the AWD decrements rated miles at ~230Wh/rmi, as measured on the trip meter.)

There is conversion loss when going from AC/DC (in the car on-board AC-DC converter), and a static load of ~250W presented by the car which does not go to the battery. There are efficiency plots posted here if you search for them which model these losses and plot efficiency vs. input power, but to first order, the efficiency is about 90% with a 5.76kW AC input (the efficiency is dependent on the input power, mostly because of the static overhead).

So, 0.9*5.76kW = 5.18kW (DC)

5.18kW (DC) / (245Wh/rmi) = 21.1 rmi/hr

Since you're getting 22 rmi/hr, the efficiency is clearly slightly better than 90% (looks like it is between 92% & 94% - though your voltages may also be slightly different than above (you can read it off the screen when it is under load) and that would matter too).

For the 32A (14-50 supplying Gen 2 UMC) charging, you'd be at about (for the AWD only!):

0.93*32A*240V / 245Wh/rmi = 29.2rmi/hr
 
Last edited:

Rocky_H

Well-Known Member
Feb 19, 2015
6,419
7,600
Boise, ID
If I change to the NEMA 14-50, approximately what is the charge miles/hr. If I do that, all i would need to buy would be a Tesla 14-50 plus the parts for the changing of the electrical circuits at home, right? Can the Tesla cable & charger can still be used when using the 14-50?
Make sure you know what you are talking about with "the parts" you would need to get. Almost certainly that circuit, which was made for a 30A outlet does not have thick enough wire to support a 40 or 50 amp circuit. So you would need to redo the wiring run through the walls to be able to make this a higher amp circuit, and I kind of doubt that's what you were anticipating doing.

But really, I kind of question why people think this is necessary if using the 10-30 outlet is already set up and so simple. You're getting 22 mph recharging speed. In 8 hours of sleeping, you get 176 miles back. Do you really need more than 176 miles every single day? I mean, you're probably going to be back home with 40 or 50 miles still in it most days, right? So that will still get you about full.
 

tm3p-fan

Member
Sep 19, 2019
76
20
FL
Thanks Rocky_H, you are right about that and yes, I know it would require a rewire, I just wanted to know because in the not too distant future I may get another EV and sharing may become an issue. My daily commute is 80miles +/- unanticipated running around. Thanks for the heads up!!
 
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