[mjr24]

Originally Posted by SkykingUSA

You will set the charging limit in the car, or in the myBMW app and then save it to the car. That setting is not normally done with the charger, so it really doesn't matter what charger you use.

Very good, appreciate the knowledge.

[SkykingUSA]

Here is the page from the myBMW app where you can set your charging stuff.

[mjr24]

So the BMW wallboxs are 40 amp units....meaning it would actually charge at 32 amps, correct (since they do 80% of the total)? How long would it take to charge from 20 to 80% with one of these?

I just wonder if it's worth it to buy one that is a 50-60 amp unit....or whether the time difference is negligible.

Also, does the BMW wallbox have a built in GFCI like a lot of charger units?

[SkykingUSA]

Originally Posted by mjr24

So the BMW wallboxs are 40 amp units....meaning it would actually charge at 32 amps, correct (since they do 80% of the total)? How long would it take to charge from 20 to 80% with one of these?

I just wonder if it's worth it to buy one that is a 50-60 amp unit....or whether the time difference is negligible.

Also, does the BMW wallbox have a built in GFCI like a lot of charger units?

I think you're getting confused between the Amps that the chargers actually charge at, and the Amps required on the circuit breaker that the charger is connected to. In the USA, the breaker in your electrical panel must be 25% higher than the Amps needed by the charger. For example, my 48 Amp charger charges the car at 48 Amps, but it's on a 60 Amp breaker in my panel. The breaker must be 25% higher Amps than the charger needs. The purpose for this is to account for surges that the charger may experience when first powering on, or at other times. Basically, the charger may spike to higher than its rated power and the circuit in your home has to be prepared for that.

In the case of a 40 Amp BMW wall box, it will charge the vehicle using 40 Amps. However, the circuit it's plugged into (or hard-wired to) must be at least 50 Amps (40 x 1.25 = 50). An electrician will be sure to provide the appropriate breaker for the charger connection.

I don't know how many hours it would take to go from 20% to 80% but I think BMW says it would take about 8 hours. You can basically presume that it would be an overnight charge if you have to go from 20% to 80% on a 40 Amp charger. Whether you need a 48 Amp unit vs. a 40 Amp unit really depends on how much you are going to drive between charges. If you can charge each night, then figure out how many miles you typically drive in a day and go based on that. Personally, I don't think it makes a significant difference for most people regarding getting a 40 Amp charger vs. 48 Amp charger.

I'm not sure about the GFCI for the charger, sorry.

[mjr24]

Originally Posted by SkykingUSA

I think you're getting confused between the Amps that the chargers actually charge at, and the Amps required on the circuit breaker that the charger is connected to. In the USA, the breaker in your electrical panel must be 25% higher than the Amps needed by the charger. For example, my 48 Amp charger charges the car at 48 Amps, but it's on a 60 Amp breaker in my panel. The breaker must be 25% higher Amps than the charger needs. The purpose for this is to account for surges that the charger may experience when first powering on, or at other times. Basically, the charger may spike to higher than its rated power and the circuit in your home has to be prepared for that.

In the case of a 40 Amp BMW wall box, it will charge the vehicle using 40 Amps. However, the circuit it's plugged into (or hard-wired to) must be at least 50 Amps (40 x 1.25 = 50). An electrician will be sure to provide the appropriate breaker for the charger connection.

I don't know how many hours it would take to go from 20% to 80% but I think BMW says it would take about 8 hours. You can basically presume that it would be an overnight charge if you have to go from 20% to 80% on a 40 Amp charger. Whether you need a 48 Amp unit vs. a 40 Amp unit really depends on how much you are going to drive between charges. If you can charge each night, then figure out how many miles you typically drive in a day and go based on that. Personally, I don't think it makes a significant difference for most people regarding getting a 40 Amp charger vs. 48 Amp charger.

I'm not sure about the GFCI for the [...]

Ah yes I might have been confused, thanks for clearing that up. Thus I’m going to need a 50 amp breaker with the 40 amp BMW wall box. I know a lot of people say you should just do a 60 amp breaker to “future-proof” it but I don’t think we will in our current house for more than 3-4 years and my lease will be 3 years….so not too worried.

[AiredaleDad]

Building code has changed over the years as far as GFCI's. For example It used to be you needed a GFCI on every outlet where moisture was a real possibility. Like Bathrooms and kitchens.

When I bought my house in WA in 2017 (New Construction) I asked the builder why there were not any GFCI's in the kitchens and bathrooms? He showed me that Code had changed and there is now a Stand-Alone GFCI in the Garage wall near the breaker box. The outlets of the kitchen and bathrooms fed through that GFCI. This was done to prevent Homeowners and DIY'ers from changing out the outlets for more custom looking ones etc. without the electrical knowledge to know to put in a GFCI outlet in those areas. Because most will go with the cheaper outlet thinking they don't need those buttons.

When I moved to Spain, I rented out my house. I recently changed tenants and the new tenant Complained to the property Manager that her Keurig blew the breaker in the garage and after resetting it it still didn't work. The Property Manager contacted me to authorize an Electrician to come fix the wiring. I informed her to have the tenant reset the GFCI in the Garage. And to refer to THE BINDER! I had given her that explained all this. She came back and said that worked, but my home was not up to code, because they needed GFCI's for each outlet. I told her the code had changed and newer houses have them in garage (AS PER THE BINDER.) And I explained the reason the Builder had given me.

A couple days later she came back and said she had contacted a Builder Friend of hers and he had said the New, New code said they have the GFCI's on the individual breakers for the kitchen, and bathrooms, in the breaker box. But that I was correct in that the one in the garage is fine because that was up to code as of the time the house was built, and had not been modified. But I asked her to send the electrician out to check that particular circuit, since it had that tendency with me as well, and with one other tenant. So I thought maybe the Kitchen circuit was under breakered for the expected load And if he could put in a larger breaker without going against code I was fine with it.

So to get to my point (I know, About time right!) It all depends on the age of your house. When you have the electrician install the Wall Box, ask him to check if it has a GFCI. If it doesn't, you can ask him to install the breaker for that circuit with a built-in GFCI on it. He will probably have one, or can go to the local Lowe's or Home Depot and get one.

[RichardInCA]

Age of the house is a good point - my town is full of houses that were built as one-off’s in the 40’s and 50’s. I don’t think I would have trusted my existing 220-240V outlets to deal with the draw of an EV charger so we put in a brand new 60Amp circuit from the main panel and had a charger hard wired. There’s nothing else in our house that pulls that much current for that long (oven, A/C unit etc) and the chance of an electrical fire just ain’t worth it.

To the OP’s question of time from 20% to 80%, I don’t have a recent session that went that long, but here’s a charging session from my house where I added 21kWh at 9kW going from 44% to 68% in 2h 18m. Doing the math that would suggest a 20% to 80% charge would take 5h 45m.

Note that AC curves are flat unlike the DC fast charging curves that get a lot of press.

[SkykingUSA]

Here is another real-world example. This is the largest charge session I have done on my car so far - 41 kWh which took 3 hours and 42 minutes at 48 Amps (48 Amps = about 11.5kW).

The screens below are from the myBMW app showing the information for this session. I'm showing the charging timeline (as well as the curve) so you can see why there is a large gap in the charge session. Basically, I had the vehicle set to charge only to 65% initially but then later I wanted to charge to 100% so I updated the limit and then the charging continued (it shows as all 1 charge session because I never unplugged the charger during this whole time).

Note: This charging was done at 48 Amps, so 40 Amps (about 9.6 kW) will take a little bit longer.

To summarize: at 48 Amps, you can fill about 50% of your battery in 4 hours, or go from 20% to 80% in under 5 hours. Roughly speaking, if you charge at 40 Amps, it will probably take between 5 and 5.5 hours to go from 20% to 80%.

[Sturob]

A couple minor points. I’m on my first EV also and I’ve been a voracious reader and question asker.

In the US generally speaking you should only run a circuit at 80% capacity; 75% is of course acceptable. But you’d max out (“”) a 60A circuit at 48A, and that’s how they’d have you set the limit on the …

here we go …

EVSU. Yes amazingly pedantically, I know, but the Wallbox isn’t a charger, it’s an EV supply unit. So is the thing that comes with the car. The charger is the device in the car that takes the power you put into it to charge the battery. So BMW’s hardware/software has final control over how the battery is charged. All the things, Wallbox, ChargePoint, etc are just fancy extension cords for your car. If you buy one, and I always call them chargers too, you’re paying for the ability to use its software to track your charging or follow your charge or whatever.

I ended up buying a ChargePoint unit, since they had a good rep, they have them at my work and haven’t had issues, and you can also tell it what utility company you use so it can figure out when kWh are the cheapest.

The current thing… I’ve read a lot of conflicting stuff about it, and I don’t say this to be argumentative. My overall impression was rather that DC charging, like on a trip at a commercial charger, is what’s hard(er) on the battery. AC charging which is at least an order of magnitude slower, even at the highest possible amperage, is gentler. I don’t know that limiting AC charging way below what your wiring and EVSU can handle is a real issue.

It’s probably always safer, though, to limit the current to whatever fits with your charging schedule, hooray if it’s significantly below the amp rating. When I charge at home, the cable between the EVSU and the car does get warm. Not hot, but warm. Using 48A on a 60A breaker with a very short run between the breaker box and the ChargePoint box.

The other point to make is that batteries like these like three things: not being full, not being empty, and electrons moving. Saying more than that about it gets into conjecture, it seems. Charging to 80%, discharging no lower than 20%: that seems to be the conventional wisdom. If you need 100% for a trip, try to start the driving as soon as you hit 100%. BMW’s software in the car can tailor a charge session to end at approximately when you think you’ll be departing for the trip.

Gosh, what else. Hmm.

The EVSU vs charger distinction is not important EXCEPT maybe to help understand that you’re always using a BMW charger to charge your battery. Whether you use the thing that comes with the car, or a WallBox, or a ChargePoint, or a Tesla (ick) EVSU is just what kind of fancy extension cord do you want.

I guess the other thing mentioned is that dryer plug sockets can have issues. I’ve seen one go up in smoke from a dryer. I went with a hardwired installation for that reason. Price? BMW’s concierge installation costs about $1000ish but depends on location and how much work it’ll take.

S

[SkykingUSA]

Originally Posted by Sturob

In the US generally speaking you should only run a circuit at 80% capacity; 75% is of course acceptable. But you’d max out (“”) a 60A circuit at 48A, and that’s how they’d have you set the limit on the

It's the same thing, just looked at from a different perspective. 60A is 25% more than 48A (48 x 1.25 = 60). Also, 48A is 80% of 60A (48 / 60 = 0.80). It just depends on whether your initial frame of reference is the 48A or the 60A. :-) Same thing in the end.

Originally Posted by Sturob

…

here we go …

EVSU. Yes amazingly pedantically, I know, but the Wallbox isn’t a charger, it’s an EV supply unit. So is the thing that comes with the car. The charger is the device in the car that takes the power you put into it to charge the battery. So BMW’s hardware/software has final control over how the battery is charged. All the things, Wallbox, ChargePoint, etc are just fancy extension cords for your car. If you buy one, and I always call them chargers too, you’re paying for the ability to use its software to track your charging or follow your charge or whatever.

I think most of us know this, but it's good to spell it out for those who are new to charging and EVs (like the opening poster). Glad you clarified it.

Originally Posted by Sturob

The current thing… I’ve read a lot of conflicting stuff about it, and I don’t say this to be argumentative. My overall impression was rather that DC charging, like on a trip at a commercial charger, is what’s hard(er) on the battery. AC charging which is at least an order of magnitude slower, even at the highest possible amperage, is gentler. I don’t know that limiting AC charging way below what your wiring and EVSU can handle is a real issue.

It’s probably always safer, though, to limit the current to whatever fits with your charging schedule, hooray if it’s significantly below the amp rating. When I charge at home, the cable between the EVSU and the car does get warm. Not hot, but warm. Using 48A on a 60A breaker with a very short run between the breaker box and the ChargePoint box.

The other point to make is that batteries like these like three things: not being full, not being empty, and electrons moving. Saying more than that about it gets into conjecture, it seems. Charging to 80%, discharging no lower than 20%: that seems to be the conventional wisdom. If you need 100% for a trip, try to start the driving as soon as you hit 100%. BMW’s software in the car can tailor a charge session to end at approximately when you think you’ll be departing for the trip.

I agree with all that as well. When I'm charging at home at 48A, the cable gets warm too. It doesn't get warm at all when I charge at 15A or less.

Originally Posted by Sturob

I guess the other thing mentioned is that dryer plug sockets can have issues. I’ve seen one go up in smoke from a dryer. I went with a hardwired installation for that reason. Price? BMW’s concierge installation costs about $1000ish but depends on location and how much work it’ll take.

I went with another company to do my hard-wired install and paid about $1200. It may have cost me a little more because they had to re-organize the breaker box since I had all my slots full and there was no room to add a new 60A breaker without removing some old ones and replacing them with newer ones.

Here is a video that warns of the dangers of 1) using low quality electrical parts (like a NEMA outlet), and 2) not using a company familiar with EVSE. It can be scary, that's why it's important to get someone who specializes in EVSE installs, or knows the specific needs for EVSE installation.

[mjr24]

So I have officially decided to just use the Gen 3 BMW Wallbox because I'm getting it free. I am going to have it hardwired just because it's safer than the NEMA plug, etc.....and probably cheaper, too, for install.

Is there any hazards at all to have my wallbox in the garage with children around? My kids aren't going to be chewing on the cord obviously....but I am assuming when you aren't charging the car you can turn the wallbox on and off, correct?

[SkykingUSA]

Since you're having it hard-wired there really isn't much to worry about in my humble opinion. Below is a picture of mine which is also hard-wired and you can see the wiring from the wall to the box is fully covered/insulated and is not flexible. I can't say if there is an on/off switch externally for the BMW Wallbox (I doubt there is), but on my Emporia unit I can only use the Emporia app to disable and enable it (among other things), but I never do - I just leave it on all the time. I'm not sure how crazy your kids are, but apart from dipping the plug into a bucket of water, there is probably not much they can do to damage the unit or more importantly, damage themselves when it's hard-wired.

Maybe someone with a BMW Wallbox can tell you what on/off options are available for that one specifically.

[mjr24]

Originally Posted by SkykingUSA

Since you're having it hard-wired there really isn't much to worry about in my humble opinion. Below is a picture of mine which is also hard-wired and you can see the wiring from the wall to the box is fully covered/insulated and is not flexible. I can't say if there is an on/off switch externally for the BMW Wallbox (I doubt there is), but on my Emporia unit I can only use the Emporia app to disable and enable it (among other things), but I never do - I just leave it on all the time. I'm not sure how crazy your kids are, but apart from dipping the plug into a bucket of water, there is probably not much they can do to damage the unit or more importantly, damage themselves when it's hard-wired.

Maybe someone with a BMW Wallbox can tell you what on/off options are available for that one specifically.

That was actually the other charger I was looking at…..but I figured it’s probably not worth the extra in install cost from getting the 60 amp breaker and heavier duty wiring that a 60 amp requires versus a 50. I don’t think we will be in our current house for more than 3-4 more years so I’m not too worried about future proofing it or else I would have definitely went with the Emporia.

[SkykingUSA]

Originally Posted by mjr24

That was actually the other charger I was looking at…..but I figured it’s probably not worth the extra in install cost from getting the 60 amp breaker and heavier duty wiring that a 60 amp requires versus a 50. I don’t think we will be in our current house for more than 3-4 more years so I’m not too worried about future proofing it or else I would have definitely went with the Emporia.

I think you'll be fine with the BMW Wallbox, especially since it's free! One thing to consider: if you are planning to move in 3-4 years, why not install a NEMA outlet and just plug in your Wallbox? That way, when you move, you can easily take it with you and plug it in at your new place. You can even have it hard-wired at the new place if you like. It's just that it would be easier to take it with you if all you had to do was unplug it. :-)

[Scrapula]

Juice box just went under and there will be no support for that charger. They had decent chargers, too. We have a Ford Charge Station Pro 80amp. Ford isn’t going under and neither is BMW. You can’t go wrong with the BMW charger as they will have to support it.

[mjr24]

Originally Posted by SkykingUSA

I think you'll be fine with the BMW Wallbox, especially since it's free! One thing to consider: if you are planning to move in 3-4 years, why not install a NEMA outlet and just plug in your Wallbox? That way, when you move, you can easily take it with you and plug it in at your new place. You can even have it hard-wired at the new place if you like. It's just that it would be easier to take it with you if all you had to do was unplug it. :-)

Couple reasons. I’m somewhat hesitant because I’ve heard NEMA outlets are not as safe. I get that if installed correctly they should be….but since I’m getting the charger free, it’s probably cheaper to get that hardwired versus having to pay for a good NEMA plug, GFCI, etc. and then still having it wired.

That’s the other reason I figured I’d keep the BMW one….this is my first electric car and I want to make sure I actually like electric cars LOL. Assuming I do, I’d just put a better charger (meaning 48v or whatever the technology is in 3 years) in the new house instead of having a 40v charger in 3 years. My guess is a 40v is going to be possibly archaic in 3 years.

[mjr24]

Originally Posted by Scrapula

Juice box just went under and there will be no support for that charger. They had decent chargers, too. We have a Ford Charge Station Pro 80amp. Ford isn’t going under and neither is BMW. You can’t go wrong with the BMW charger as they will have to support it.

Interesting, that’s good to know as I know that was a company that a lot of people used.

[Kennethjk]

You might want to check your local utility to see if they are offering any rebates on a particular unit. There are many good ones out there.

I got $450 off my Juicebox, a 40 amp unit that was a plug in. Direct wiring is safer as 1 less point of failure and yes if you do go the plug in route, get a Hubble unit, industrial strength. I understand there is another company that makes one as strong. I went with plug in, in case the unit broke. I wouldn’t need an electrician to take off the old unit and or install the new unit and if the old one was bad I could just plug in the BMW unit until I get a replacement. As it turned out I had to replace 2 Juicebox units since they went bad within the warranty.

Unfortunately they are closing down their support and the unit will most likely be a dumb unit shortly. The only thing I ever did with the juicebox was down rate the amp charge. I normally charge at 32 amp. Less heat and less stress on battery and equipment.

Going forward I will adjust amp thru the car itself. I only charge at 40 amp if time is of the essence.

Dumb units, no adjustments thru the phone and are cheaper than smart units which have apps that coonect to the EVSE and you can measure various things

Enjoy

[mjr24]

Probably a “dumb” question….pun intended….but what is a dumb charger?

I’m assuming it basically just charges with no real way to change settings?

Edit: duh it’s late, I missed your last paragraph. Never mind.

So I can basically tell the car in its settings what to charge at, right?

Like you said….you usage a 40 amp charger and obviously the max the car can take is 48. Would something break either on the car or with the charger if you forgot to tell the car to charge at 40 (and instead you told it to charge at the full 48)?

[SkykingUSA]

The car will not break by plugging into a more powerful supply than it can charge at. Remember, the "charger" is inside the vehicle which controls how the car charges and at what power levels, etc. The things on the wall that are generally called "chargers" are really just power supplies that have the ability to supply different levels of power to the chargers inside cars (that's why they are called EVSE, or Electric Vehicle Supply Equipment).

Basically, your car won't let itself charge at higher levels than it is capable of. A good example of this is when you plug into a public DC fast charger that is rated for up to 350 kW. Even though the DC fast charger can provide up to 350 kW of power, the car can only accept about 205 kW, so the car will control how much power is actually accepted. Same with the wall boxes at home - if your wall box can provide 80 Amps (like a Ford pro charger), your car will still limit its maximum charge to 48 Amps (or whatever lower limit you may have set in the myBMW app or the car).

Don't worry, once you learn about it and try it a few times, it's easy and you'll be so happy that you don't have to go to the "gas station" anymore (unless you're going on a very long trip). The convenience of just plugging your car in at home and having it always ready for you is great!

Edit: Even though some "chargers" (really EVSEs) have the ability to change how much power they can put out, and have "smart" capabilities like remote control and reporting, it will not override the limits set by and within your vehicle. The vehicle will always win because it contains the "real" charger with the charging logic and control. Think of it as car self-preservation. :-)

[Scrapula]

We have a smart charger but it’s a dumb charger for me. I just plug in and use the settings of my car. My husband looks at the Ford charger app which reports things like dollars spent for both vehicles but we don’t use any of the other features.

[mjr24]

Originally Posted by SkykingUSA

The car will not break by plugging into a more powerful supply than it can charge at. Remember, the "charger" is inside the vehicle which controls how the car charges and at what power levels, etc. The things on the wall that are generally called "chargers" are really just power supplies that have the ability to supply different levels of power to the chargers inside cars (that's why they are called EVSE, or Electric Vehicle Supply Equipment).

Basically, your car won't let itself charge at higher levels than it is capable of. A good example of this is when you plug into a public DC fast charger that is rated for up to 350 kW. Even though the DC fast charger can provide up to 350 kW of power, the car can only accept about 205 kW, so the car will control how much power is actually accepted. Same with the wall boxes at home - if your wall box can provide 80 Amps (like a Ford pro charger), your car will still limit its maximum charge to 48 Amps (or whatever lower limit you may have set in the myBMW app or the car).

Don't worry, once you learn about it and try it a few times, it's easy and you'll be so happy that you don't have to go to the "gas station" anymore (unless you're going on a very long trip). The convenience of just plugging your car in at home and having it always ready for you is great!

Edit: Even though some "chargers" (really EVSEs) have the ability to change how much power they can put out, and have "smart" capabilities like remote control and reporting, it will not override the limits set by and within your vehicle. The vehicle will always win [...]

So I don’t have to worry about the car trying to charge at 48 if my wall box only does 40? Will my car sense that and automatically change the charge rate to 40 or will I have to do that myself? I guess that’s my what could happen if I forget to do that? Obviously it’s moot if the car indeed senses it….