Help with home charging system: 10 30A, 240V, 24A

[WB21]

Hi all. I just set up my home charging system and have some questions.

There are two 30A circuit breakers connected to an unused 10 30A outlet in my garage. The voltage is 240 V.

I connected my 2018 model S to the outlet using a NEMA 10 30 adapter from Tesla, and set the amps at 24A.

I was under the impression that this would gain 22 mph of charging. However, after 2 hours of charging, I gained 27 miles, about 13 mph.

Anyone have any similar experiences or advice on what the issue could be? Should I set my amps differently? Or something else? Thank you.

 

[ucmndd]

Wall Connector

The Tesla Wall Connector is the most efficient way to charge a Tesla at home — just plug in your vehicle overnight and wake up to a charged vehicle.

www.tesla.com

Tesla’s current charging chart suggests that a new Model S will get about 17 miles per hour on a 30 amp circuit, not 22 like you suggest.

That’s a NEW Model S, which is more efficient than your 2018, so it will get more “miles per hour” for the same amount of electricity.

13 miles/hour sounds right for your car on a 30 amp plug. There’s nothing for you to really change. If you’re set to 24 amps and getting ~240 volts, you’re receiving the max 5.7kw of power that outlet can provide.

 

[WB21]

Seems like the 22mph of charge applies to Model 3s. I read that 17 is more standard for a Model S. In that case, seems like my 13 mph is up to par? Especially since I charged from 64% to 80%, given that charging speeds tend to slow down later in the charge cycle.

 

[WB21]

Wall Connector

The Tesla Wall Connector is the most efficient way to charge a Tesla at home — just plug in your vehicle overnight and wake up to a charged vehicle.

www.tesla.com

Tesla’s current charging chart suggests that a new Model S will get about 17 miles per hour on a 30 amp circuit, not 22 like you suggest.

That’s a NEW Model S, which is more efficient than your 2018, so it will get more “miles per hour” for the same amount of electricity.

13 miles/hour sounds right for your car on a 30 amp plug. There’s nothing for you to really change. If you’re set to 24 amps and getting ~240 volts, you’re receiving the max 5.7kw of power that outlet can provide.

I was literally posting this just as you replied haha. Good to know! Thanks for the explanation, that definitely makes sense now that I look more into it.

 

[ucmndd]

BTW those “two circuit breakers” in your panel should be ganged together such that if one trips the other is opened with it. You want those two breakers to function as one single circuit.

 

[M3BlueGeorgia]

Seems like the 22mph of charge applies to Model 3s. I read that 17 is more standard for a Model S. In that case, seems like my 13 mph is up to par? Especially since I charged from 64% to 80%, given that charging speeds tend to slow down later in the charge cycle.

You shouldn't see a slow down while doing A/C charging.

Also 10-30 doesn't have a ground. Please consider having an electrician convert it to 14-30, which superceded 10-30 in 1997.

 

[ucmndd]

Seems like the 22mph of charge applies to Model 3s. I read that 17 is more standard for a Model S. In that case, seems like my 13 mph is up to par? Especially since I charged from 64% to 80%, given that charging speeds tend to slow down later in the charge cycle.

Like I said, “up to 17” would apply to a new Model S, which is more efficient than yours. Miles per hour is not a good way to measure power, as you’re finding out.

It’s not related to charging speeds slowing down due to state of charge. That’s irrelevant at home/L2 charging speeds - you won’t notice a slowdown until your state of charge is >95%.

 

[WB21]

You shouldn't see a slow down while doing A/C charging.

Also 10-30 doesn't have a ground. Please consider having an electrician convert it to 14-30, which superceded 10-30 in 1997.

Got it, thanks for the info. Is it unsafe to continue using it as it is? The previous owner charged with 10 30 and I’ve read other people use a similar set up. But I’d like to hear your insight.

 

[WB21]

Like I said, “up to 17” would apply to a new Model S, which is more efficient than yours. Miles per hour is not a good way to measure power, as you’re finding out.

It’s not related to charging speeds slowing down due to state of charge. That’s irrelevant at home/L2 charging speeds - you won’t notice a slowdown until your state of charge is >95%.

Understood! Thank you.

 

[WB21]

BTW those “two circuit breakers” in your panel should be ganged together such that if one trips the other is opened with it. You want those two breakers to function as one single circuit.

Yes, those two are in the same position!

 

[M3BlueGeorgia]

Got it, thanks for the info. Is it unsafe to continue using it as it is? The previous owner charged with 10 30 and I’ve read other people use a similar set up. But I’d like to hear your insight.

Got it, thanks for the info. Is it unsafe to continue using it as it is? The previous owner charged with 10 30 and I’ve read other people use a similar set up. But I’d like to hear your insight.

There's a reason that NEMA moved from 10-30 to 14-30 ... And the difference is having a ground.

Tesla don't use the neutral (which is the current third prong on 10-30).

When we sold our 1980's house about 7 years ago, the inspection caught that we were using the 10-30 outlet for the electric clothes dryer and we had to bring in an electrician to bring it up to code by swapping to the 14-30. However, my mother-in-law's condo sold a couple of months ago without us being forced to upgrade its dryer outlet, but it was a different county, so maybe different standards?

 

[jeremymc7]

You shouldn't see a slow down while doing A/C charging.

Also 10-30 doesn't have a ground. Please consider having an electrician convert it to 14-30, which superceded 10-30 in 1997.

I’m charging on a 10-30 dryer outlet as well. Two inspections when purchasing a decade ago gave a list of things to bring up to code. The outlet wasn’t one. In my state / county they are grandfather led in if existing. You can’t add a new 10-30. If you need a new dryer outlet you have to run a ground and install a 14-30. If there you can leave it.

Can this be done without running a new / additional wire for the ground? If so it’s not always advisable as some electricians have told me. I’m on a 60’s two wire system myself. Ive been told there’s not much room to work with in my case given the other existing cables when they took a look. Not to mention all the other work that’s been done in the past 50+ years. They also mentioned that given prior plus age of wire they not only would have a hard time but also might damage existing wire, which would require pulling perfectly functional wire. They were willing to do the work but advised against it.

 

[M3BlueGeorgia]

Can this be done without running a new / additional wire for the ground? If so it’s not always advisable as some electricians have told me. I’m on a 60’s two wire system myself. Ive been told there’s not much room to work with in my case given the other existing cables when they took a look. Not to mention all the other work that’s been done in the past 50+ years. They also mentioned that given prior plus age of wire they not only would have a hard time but also might damage existing wire, which would require pulling perfectly functional wire. They were willing to do the work but advised against it.

Sounds like you have bigger ground problems.

We moved to a (smaller) 1960s house a few years ago and before we moved in we had the house rewired from it's 2-wire system with a fuse box to a 3-wire system with a breaker box.

 

[jeremymc7]

Yes, those two are in the same position!

Same position means nothing. They need to be attached so if one side blows it takes the other with it. Those two separate breakers need to be replaced with the proper one. This is a must.

 

[jeremymc7]

Sounds like you have bigger ground problems.

We moved to a (smaller) 1960s house a few years ago and before we moved in we had the house rewired from it's 2-wire system with a fuse box to a 3-wire system with a breaker box.

Rewiring wasn’t really an option. 4 bed, 3 bath, 2 stories, oversized garage, multiple patios and balconies. Outlets, lights and switches everywhere. It would have cost a fortune. That’s all before decades of rewiring and walls being moved prior to me.

 

[WB21]

we

Same position means nothing. They need to be attached so if one side blows it takes the other with it. Those two separate breakers need to be replaced with the proper one. This is a must.

yes, that is what I meant. They are attached and move together when turned on or off.

 

[ucmndd]

The 10-30 is fine. I’d not fuss with it. 95 times out of 100 the circuit is terminating at the main panel where neutral and ground are bonded anyway.

The Tesla UMC won’t charge if it doesn’t detect an acceptable ground.

 

[dark cloud]

Hi all. I just set up my home charging system and have some questions.

There are two 30A circuit breakers connected to an unused 10 30A outlet in my garage. The voltage is 240 V.

I connected my 2018 model S to the outlet using a NEMA 10 30 adapter from Tesla, and set the amps at 24A.

I was under the impression that this would gain 22 mph of charging. However, after 2 hours of charging, I gained 27 miles, about 13 mph.

Anyone have any similar experiences or advice on what the issue could be? Should I set my amps differently? Or something else? Thank you.

You may be getting 24 Amps, but are you getting 240 volts? I get 243-244 Volts routinely with my 48 amps, and I have been at level 2 chargers that state 240 v but only put out 208 v. for whatever reason. Your car screens and the ap will show you.

Something else to double check: I know there have been some connectors/plugs that have been recalled; don't have it memorized off the top of my head, not sure if it is the 10/30 or 14/30 or some other one, I recall a white vs. black difference, but if you are using some old used mobile connectors from somewhere I would double check the ones you are using are fine.

 

[WB21]

You may be getting 24 Amps, but are you getting 240 volts? I get 243-244 Volts routinely with my 48 amps, and I have been at level 2 chargers that state 240 v but only put out 208 v. for whatever reason. Your car screens and the ap will show you.

Something else to double check: I know there have been some connectors/plugs that have been recalled; don't have it memorized off the top of my head, not sure if it is the 10/30 or 14/30 or some other one, I recall a white vs. black difference, but if you are using some old used mobile connectors from somewhere I would double check the ones you are using are fine.

At 24A the car screen would show between 243 and 245V.

And don’t think the recall would apply to my cords because I ordered the adapter from Tesla a couple weeks ago. The cord that came with the original Tesla and the new adapter are both black. Any idea on the significance ?

 

[Rocky_H]

And don’t think the recall would apply to my cords because I ordered the adapter from Tesla a couple weeks ago. The cord that came with the original Tesla and the new adapter are both black. Any idea on the significance ?

That was a very old recall on the Gen1 mobile connector adapters. Tesla switched to the Gen2 mobile connector since about 2018, so it definitely doesn't apply to you.