Wall connector installation

[Runt8]

Charging at less than the max 48 Amps the car supports reduces stress on the in-car charger that converts AC to DC power, extending its life. It is fine to run at 48 Amps when helpful, but most of the time the car will be fully charged every morning at lower charge rates. I charge my Teslas at 16 Amps (240 V) and they are always fully charged in the morning (my wife and do not have long commutes).

Do you have any information to actually back this statement up? I’ve never seen anything that suggests higher charging rates causes any problems with the chargers. But charging slower is less efficient and will cost you more.

 

[gilscales]

Regarding purchasing an actual Wall Connector, I was thinking I would just buy the new black one with the 24 foot cable from Tesla. Does that make sense? "Gloss Black Wall Connector"
I think Tesla just introduced this new version in October.)

Those HPWC units need to be hard wired, your mobile connector that came with the car can be plugged into the dryer outlet with a $35 adapter sold by Tesla

If you wish to have the HPWC that you mention you can remove the outlet and mount an extension box like this Buy Electrical Box Accessories - Free Shipping over $50 | Zoro.com you will put a blank cover plate over the extension box

Then you can come off the side of the extension box with a surface mount conduit that terminates into the HPWC, using short lengths of 8 Gauge wire you can splice to the end of the wire in the outlet box to run through the surface mount conduit and into the HPWC for a hardwired solution and set the maximum charging rate of the HPWC to 24A

Use heavy duty splice blocks of some sort instead of wire nuts, something like this https://www.amazon.com/Morris-Produ..._rd_t=40701&psc=1&refRID=697ACZRM9ZCMABD46KD8

 

[voip-ninja]

Do you have any information to actually back this statement up? I’ve never seen anything that suggests higher charging rates causes any problems with the chargers. But charging slower is less efficient and will cost you more.

I don’t believe there is a damn thing to back that assertion up.

 

[voip-ninja]

Regarding purchasing an actual Wall Connector, I was thinking I would just buy the new black one with the 24 foot cable from Tesla. Does that make sense? "Gloss Black Wall Connector"
I think Tesla just introduced this new version in October.)

Yes if cost isn’t objectionable then there are a few advantages to going with the HPWC. The longer cord is nice if you ever need to charge a second car or even charge in the driveway.

The HPWC is weather rated so you could even install it outside of the home if you normally park outdoors.

I would recommend running the largest circuit you can get permit approval for since labor is a big part of the cost and your wiring run is not very far. You can then decide if you want to run a 30 amp or 50 or 60 amp breaker if you have enough capacity for that.

While you can usually charge overnight there could be situations in which you want to put some range on the car at home and head back out again quickly and in those cases you want the fastest AC charging you can get.

 

[eprosenx]

Is it bad if you occasionally trip your main breaker? Like if you forget not to use the toaster and oven at the same time while you are charging?

Yes, you should never be tripping breakers in a properly designed and installed system. Breakers are only a backup safety mechanism. Load calculations are the primary mechanism to prevent fires. Breakers are an additional line of defense. Note that breakers sometimes fail to function!

Thanks a lot. What is the maximum power draw of the wall connector. ( I am thinking 48 amp at 240 volts for a long-range, all wheel drive model 3. Is that correct? What size circuit breaker would one need to enable that?)

The Wall Connector can be installed on up to a 100a circuit, though as others have pointed out, the Model 3 LR can only make use of up to a 60a breaker (48a continuous). Model S/X units can make use of up to a 90a breaker (or older S's with dual chargers can make use of the full 100a).

To verify your dryer is gas, can you turn off the dryer breaker and then operate the dryer? If it is gas, it will be plugged into some other 120v circuit to run the motor.

So I am not convinced that you can't do 60a. Depending on the conduit/wire paths available, I might consider running 6 AWG in conduit (assuming it does not get too hot in an attic - otherwise you need bigger wire) and doing a full 60a circuit. Or you could do 4 AWG romex. You need to look in detail at your load calculations, but your house has as minimal load as possible other than the oven (but I think you can probably still do a 60a circuit). I personally love being able to charge my car at the full 48a and NEVER have to worry about charging being slower than the car is capable of.

Breaker position wise: I am dead curious how many empty spots you have above. It looks like at least one. Hopefully you have two spots available, but if not - I wonder if you are allowed to use a tandem for your Solar backfeed breaker? I did when I consolidated for my Tesla charger install, but now I wonder if that is not supposed to be allowed? You can get Tandems from Eaton in up to 50a. Above that you need full size breakers. As others have stated, if your dryer is unused you could disconnect those wires in the panel and cap them off and then put in a breaker that is say 50a and use that. So you have options! (also you could re-use the dryer wires depending on where they go, but they would only support 30a (24a) charging.

I totally disagree with folks advising to charge slower to reduce wear and tear and energy loss. In a proper electrical system that follows code with proper conductor sizes, heat loss is very low. I don't factor this in at all. I see no reason to believe that Tesla's are not designed to run at 100% of their rated charging capacity every day. This is what I do and it has worked flawlessly since July. Conceptually this is true, but it also runs your cooling pumps, etc, for longer so you have to factor in that wear and tear.

For Time of Use pricing, you often are trying to fit a full charge into a six or eight hour window, and so I just like having max charge rate available to me (even though the math says you can do it with a smaller circuit).

On the cable management for the Wall Connector- I mounted mine outside. I did not use the bracket that can go on the back for Top Entry. I have no problems hanging the cable off the unit. I just use big loops. What you are seeing here are the two loops I take off every day to charge the car and then put back on later. The small loop is slack that stays on all the time. Note that optimally you really want to be able to do this one handed - so the 8' unit in the exact right spot is appealing. I end up leaving the cord on the ground a bit since I need two hands to coil it back up.

Even if you don't go 60a, then 50a I think is totally doable. The nice thing about 50a is that you can do Tandem breakers for 50a and you can use 6 AWG Romex as the feed which is very manageable (only good to 55a since NM cable - romex - is only allowed to use the 60c rating). If you run through the crawl space or attic, Romex might be easier than a lot of complicated conduit bends.

When you send pictures, please also take a picture of the inside flap of the panel with any gory technical details available (sufficient resolution so we can read the fine print). Most importantly getting the model # might allow us to find the specifications.

Let us know what you decide to do! I look forward to seeing pictures of your final install!

 

[GSP]

Thanks a lot GSP. Really good to know. So far I have only charged at home with the 115 V plug and at superchargers. That makes a lot of sense. So when you are using the in-board charger at home, going slow makes a lot of sense. Maybe even just like 8 miles per hour?

I hadn't thought about that because, my at home charging has been so slow already (4 mph). I am only realizing in reading your comment that charging at home is fundamentally different from the supercharger, which bypasses the on-board charger, and that just because you can charge at an ultra-high rate on the road doesn't mean that a high rate at home is benign or comparable in any way.

No need to go ultra slow. Just dropping to 75% of max rate significantly drops the temperature of connections and the charger (AC to DC converter) increasing their life.

Really low rates, like a 120 V outlet, are less energy efficient since battery heating or cooling and other fixed electrical loads are present for a longer time.

GSP

 

[GSP]

Do you have any information to actually back this statement up? I’ve never seen anything that suggests higher charging rates causes any problems with the chargers. But charging slower is less efficient and will cost you more.

Other TMC members that have experience with electrical power systems have offered this advice, saying that it applies to most electrical equipment. Their recommendations make sense to me based on my more limited experience.

Also, early Tesla UMCs and 40 A chargers had several failures under warranty, almost always when used at the full 40 A. Other customers had no problems at 40 A, so it was just a percentage. Tesla issued a sw update to drop actual amps to 39 when 40 was displayed.

GSP

PS. I am not advocating never using the max charge rate, but to not use it when it is not needed or not useful. Same guideline as for charging to 100% SOC. Also, don’t drop way below max rate, just 75% or so. The early 40 A UMCs has 32 A rated relays inside, and run pretty hot at 40 A.

 

[voip-ninja]

Other TMC members that have experience with electrical power systems have offered this advice, saying that it applies to most electrical equipment. Their recommendations make sense to me based on my more limited experience.

Also, early Tesla UMCs and 40 A chargers had several failures under warranty, almost always when used at the full 40 A. Other customers had no problems at 40 A, so it was just a percentage. Tesla issued a sw update to drop actual amps to 39 when 40 was displayed.

GSP

PS. I am not advocating never using the max charge rate, but to not use it when it is not needed or not useful. Same guideline as for charging to 100% SOC. Also, don’t drop way below max rate, just 75% or so. The early 40 A UMCs has 32 A rated relays inside, and run pretty hot at 40 A.

You are pouring out misinformation. There is zero indication that charging at a lower 240V rate does ANYTHING for the life of the battery or the longevity of the charging system.

The car is designed to eventually handle relentless charging with level III super-charging at over 150 kWh and you think that charging on AC at 9 kWh is going to harm the battery?? Really?

Please stop providing FUD disinformation it is harmful to others.

Citing as your source "other forum members have said...." is as bad as it gets.

 

[BerTX]

You are pouring out misinformation. There is zero indication that charging at a lower 240V rate does ANYTHING for the life of the battery or the longevity of the charging system.

The car is designed to eventually handle relentless charging with level III super-charging at over 150 kWh and you think that charging on AC at 9 kWh is going to harm the battery?? Really?

Please stop providing FUD disinformation it is harmful to others.

Citing as your source "other forum members have said...." is as bad as it gets.

There are probably a lot of things I do in life because it "might help" or some person who supposedly knows has said so . You weigh the cost in time and money against the potential reward, and decide.

In this case it increases charge time by maybe an hour a day, x days a week, and the extra power overhead is about 0.5 kWh. The price of a couple of lattes a year is pretty cheap insurance.

Not disagreeing that there is no proof that charging at a slightly lower rate helps preserve the battery. Lack of proof is not disproof.

The only reason I don't charge at a lower rate is that I often decide that I want to charge to a higher starting SOC for a drive (I live in the sticks of Texas), and do that as quickly as possible . I'd have to walk outside and change the amp setting, since the app can't do that. So that usually tips the balance to charging at the higher rate.

 

[voip-ninja]

There are probably a lot of things I do in life because it "might help" or some person who supposedly knows has said so . You weigh the cost in time and money against the potential reward, and decide.

In this case it increases charge time by maybe an hour a day, x days a week, and the extra power overhead is about 0.5 kWh. The price of a couple of lattes a year is pretty cheap insurance.

.

Insurance against what exactly? Nobody at Tesla have ever indicated that it is better for the charger, the HPWC or the battery to charge it at a lower level. I'd actually argue that the opposite is more likely the case.

The problem I have is that people don't start off offering this shoddy advice by saying "there's zero empirical evidence that charging at a lower amperage level is better for the system, and it costs a bit more in charging overhead... but I choose to do it anyway because in my gut I feel it's better".

Instead they offer it up as fact.. and people not as well informed may take it to heart since the person presenting the "info" tries to present it as if it's established fact instead of an opinion, like the belief that voodoo can bring back the dead.

Here's what gsp posted;

Charging at less than the max 48 Amps the car supports reduces stress on the in-car charger that converts AC to DC power, extending its life. It is fine to run at 48 Amps when helpful, but most of the time the car will be fully charged every morning at lower charge rates. I charge my Teslas at 16 Amps (240 V) and they are always fully charged in the morning (my wife and do not have long commutes).

This is flagrant misinformation not being presented as an opinion, like believing that hanging a horseshoe over your threshold gives you good luck, it is being presented as a FACT.

I have a real problem with that, as you can probably tell.

 

[Big Dog]

But charging slower is less efficient and will cost you more.

Do you have any research data to backup your assertion? Electrons are electrons. The electric company only charges you for what you use, not how fast you use them.

Yes, charging at say, 32 is slower than 48. But, efficiency depends on the temp. If its 105 degrees at night in Phoenix, charging at 48 may crank up the heat enough so that the battery has to self cool using more electrons, i.e., less efficient. OTOH, perhaps more efficient to charge at full blast in winter in Denver. Of course, the charge will cycle on and off to hold 80% (or whatever your target is.) If its bitter cold, vampire drain will take out a few miles causing the charger to kick back on, no? (guessing that's how it works.)

 

[BrandonLive]

I know that higher voltage is more efficient for transmission. Not sure about higher amp charging in terms of efficiency, though I think I’ve seen that claimed on here as well. Actually I think it may have been due to not having to run the battery thermal management system as long, at least as one factor.

 

[voip-ninja]

Do you have any research data to backup your assertion? Electrons are electrons. The electric company only charges you for what you use, not how fast you use them.

Yes, charging at say, 32 is slower than 48. But, efficiency depends on the temp. If its 105 degrees at night in Phoenix, charging at 48 may crank up the heat enough so that the battery has to self cool using more electrons, i.e., less efficient. OTOH, perhaps more efficient to charge at full blast in winter in Denver. Of course, the charge will cycle on and off to hold 80% (or whatever your target is.) If its bitter cold, vampire drain will take out a few miles causing the charger to kick back on, no? (guessing that's how it works.)

There is a certain amount of overhead when charging to operate the charger and other electronics. If you charge at a slower rate you will incur more overhead due to charging for a longer period before the car can go back to sleep.

Additionally if any components have a lifespan measured in usage hours vs current level those parts would wear out faster due to added hours put on them.

 

[MaryAnning3]

Is Romex good? What size would you use for 50 amp? (about 50 feet from box to HPWC)

 

[Big Dog]

There is a certain amount of overhead when charging to operate the charger and other electronics. If you charge at a slower rate you will incur more overhead due to charging for a longer period before the car can go back to sleep.

Additionally if any components have a lifespan measured in usage hours vs current level those parts would wear out faster due to added hours put on them.

Sure, but is the so-called "overhead" dollars or fractions of a penny?

And as to your second point, all batteries prefer cooler vs hotter, so they would generally prefer a slower charge if the 48 amp would over heat them. The rest of the components are pretty basic stuff: electrical motors and wires have been around longer than internal combustion engines. If they wear out faster from charging @ 32 amp vs 48 amp, Elon has a serious design problem.

 

[miimura]

Is Romex good? What size would you use for 50 amp? (about 50 feet from box to HPWC)

Romex is only good inside walls or crawl spaces. All wire exposed outdoors, in a garage, or a basement must be protected in a conduit of some kind. 6 AWG is the normal size for a 50 amp circuit. However, there are exceptions that might require a larger size or higher temperature insulation.

 

[voip-ninja]

Sure, but is the so-called "overhead" dollars or fractions of a penny?

And as to your second point, all batteries prefer cooler vs hotter, so they would generally prefer a slower charge if the 48 amp would over heat them. The rest of the components are pretty basic stuff: electrical motors and wires have been around longer than internal combustion engines. If they wear out faster from charging @ 32 amp vs 48 amp, Elon has a serious design problem.

I'm not sure how much overhead it is. I saw some estimates that just charging the car uses between 500 watts and 1000 watts, there was a lengthy thread in the "other" forum about the charging overhead. It impacts most for those charging at 120V.

As to your second point, you contradict yourself. Even though "mean time before failure" is a completely well known and industry accepted standard in electronics that measures average operational time before failure, you are dismissive of it.... yet you opine that "all batteries would prefer cooler" and then imply that 32amps somehow keeps the batteries cooler than 48 amps. The batteries are cooled which is why they can accept much higher direct DC current levels than anything possible with home AC charging.

If it's your opinion that the car will hold up better and the battery won't degrade as much if you charge at 32 amps than 48 amps that's fine, you can have that opinion and base it on something pretty flimsy, but it still isn't a fact.

 

[RayK]

@MaryAnning3 to answer your question from earlier....

Wall Connector

 

[voip-ninja]

@MaryAnning3 Did you end up getting this work quoted? What did you elect to do?