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Decision Time: 48A or 72A Home charging?

Discussion in 'Model S: Battery & Charging' started by IT Geek, Apr 20, 2017.

  1. Rocky_H

    Rocky_H Active Member

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    OK, very helpful with the picture. It took me a few seconds to process what the labels meant, because I was thinking, "Both sections of that wall are "inside" your garage." But you mean the part on the right has your house on the other side of that wall, while the part on the left has open air on the other side of the wall.

    I know you said you don't want conduit, but.... With where you want that wall connector, that is by far the easiest. OK, how about this? Install some wall rack shelving on a partial section of that wall, coordinated with where the conduit will run, so it is just under one of the shelves, so it is hidden and people can't see it.

    My other thought is: You said you have the version with the 24 foot cord. I would think you could still mount it on that right section of wall, and the cord should still reach out to the driveway all right.
     
  2. BrettS

    BrettS Member

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    My garage is actually very similar, but the 'outside' part of my garage is just painted cinderblock, so I didn't really have an option to run the wires through the wall. However, most of the run is in the garage attic and I just brought the conduit down and into the top of the wall connector. Do you have an accesssible attic in your garage? Could they run the conduit through there and then bring it down in the wall between the studs?
     

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  3. IT Geek

    IT Geek Member

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    No attic in the garage. They just ran the drywall all the way up. I have a ranch house, but with very tall ceilings 9' and 10' in some places. The ceiling in the garage is actually 20' above the cement floor. From doing some measuring it looks like parts of my basement actually extends up 30" or so above the floor of the garage. So when they drill thru the middle of the floor joists into the garage they will actually be almost 3' off the floor of the garage.

    I could potentially just go straight up from where they pull the wire thru the basement and put the charger right above the red block in my pic. Will have to measure though to see how much cable that leaves me to get outside though.
     
  4. boaterva

    boaterva Supporting Member

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    Keeping it all hidden will definitely add to the complexity. The main reason to run 100 Amps would be if you ever wanted to have two HPWC's for two Teslas; you say you don't, but that's part of future proofing. :). See my sig for pix of how we ran a subpanel and broke out the circuit to two HPWCs. All in conduit that looks pretty good, I think. But that's all personal preference. Note I also have a 'transfer switch' so I can have an emergency 14-50 also for backup.
     
  5. davewill

    davewill Active Member

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    I'm confused. Why can't they just run the wire up from the basement where your red block is, then through the finished wall to where you want the HPWC? They would have to do some drywall repair, but that's a normal procedure. Personally, I would save money and do conduit since it's a garage, but they should be able to do it your way.
     
  6. IT Geek

    IT Geek Member

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    I've done some more measuring and checking and what you described is what is what is going to happen. The wire will go from the basement to approximately where the red block in the picture is and then go over to the left inside the 2x6 walls till it gets to be about 3' or 4' from the garage door opening. That way I'll be able to use the cord outside if ever that's necessary. It's not long enough to make it from where the red block is...so I have to go more towards the door to get that feature, besides it will be closer to where the charge port is on the car as well.

    Also, after the electrician talked things over with the city it looks like I'm going to go with the 48 amp setup for a few reasons. First the 100 amp would require a visible disconnect, which I don't want to see. Second, the panel in the basement is over 75' away from where I want the charger so that wire cost becomes significant. Lastly, If I ever need to charge 2 cars, I'll just get a NEMA 14-50 run to another spot in the garage and use the UMC that comes with the car.

    I know different people have different takes on what is good enough for a garage. As for me, I intend to keep mine very clean and organized and I'd prefer to not see the conduit so I'm going to have the wire run in the walls and the patch up the drywall.

    Furthermore...the walls in there are beige and that's not working for me...so any excuse to get them painted a different color is absolutely welcome. :)
     
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  7. tpham07

    tpham07 Active Member

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    It might just be easier to have them run a conduit outside the house and then drill a hole thru the wall and back into the garage where you want the charger. If you don't mind the obvious aesthetic deficiency with that plan, then go for it if it saves you time/money. Personally if it were me i'd go for the 90A breaker/72A charging capability just to future proof. The wall connector is already capable of it and the cost difference between that and 60A/48A service is negligible. I plan on upgrading to a hi-amperage 72A charger in the future along with installing a wall connector. I've already run into a few times when i thought to myself "damn i wish the car would charge faster."
     
  8. tga

    tga Supporting Member

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    Installing a HPWC @ 48A requires a 60A circuit which need 6 ga wire. If you upgrade to 4 ga, you can go up to 85A (charging at 85A * 80% = 68A). NEC 625.23 only requires the disconnect for over 60A charging.

    Assuming your car has a 72A charger, upgrading from 6 ga to 4 ga would get you 60A charging without needing a disconnect. The wire cost increase would be ~$0.30/ft, or <$25 for the 75' run.

    If it were me, I'd seriously consider having them install 2ga, for future upgradability to 80A charging - the wire would be ~$50 more than 4ga ($75 more than 6ga).
     
  9. Olle

    Olle Member

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    I went through a similar decision making process too for our garage back in 2015. We were chosing between 50A (40A charging) and 100A (80A charging) though. We went with 50 mainly because there was no Romex allowable by code for 100A. We would have had to run THHN in conduit outside the wall. With 50A we could run Romex through the studs with everything hidden.

    Most importantly though; we use the Tesla as our main car, even for road trips, and have never needed more than 40A charging during the 2 years we had this install.
     
  10. boaterva

    boaterva Supporting Member

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    One reason to go 'whole hog' and install 2 AWG for 100 Amps to charge at 80 is to support two HPWCs in load sharing mode. If you ever think having two Teslas with two HPWCs is a possibility (and it is recommended to have them plugged in all the time when 'at home'), that's the easiest way to get 30-40 Amps to each one. You can always add the extra cabling/conduit/data cable for the second one later.

    Of course there are a lot of ways to work around having two cars, but that's one way to have 'full' charging to both of them easily. (See my sig for my implementation.)
     
  11. Olle

    Olle Member

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    #31 Olle, Apr 26, 2017
    Last edited: Apr 26, 2017
    Another way of future proofing is to run several 60 A romex each with its own 60A breaker and its own HPWC for each parking spot. Or maybe an HPWC with 60A in one spot and NEMA 14-50 in another, with 50A breaker. Or just 14-50 and mobile connector with a nice Tesla wire organizer. This was you can charge any EV. and staying at 60A you can keep everything concealed in the wall, and no extra disconnect needed.

    This is what we did. We have 3 EVs in the family of which only one Tesla. and this setup works beautifully. Any car can charge in any spot. Tesla with Mobile connector and the others with J1772. All connected to their own NEMA 14-50
     
  12. boaterva

    boaterva Supporting Member

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    The only 'problem' with this is that you may run out of 'headroom' in the load calculation. One 100 Amp circuit counts as that. two 60's or a 60 and a 50 or whatever is more, of course. :) The good thing about the load sharing arrangement is that either 'stall' can get full speed (if equipped with the high-powered charger, of course). And we have no idea what the Model 3 charger options will be.

    (I do see that you're 'satisfying' a mix of cars, not all Teslas, which complicates things a bit, of course!)
     
  13. Olle

    Olle Member

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    Agreed! definitely pros and cons with both methods
     
  14. suraj1194

    suraj1194 Member

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    I drive a LOT more miles than you on a daily basis (e.g. ~150 miles often on successive days) and 48A works just fine for me. And no, I don't have to leave with half a charge and wheeze into a supercharger to top up. On many occasions I've gotten home with 15% SoC and filled it up to the usual 90% overnight before heading out next morning. I've never considered 'gee it would be nice to have 72A'. If my car came free with it, I still probably wouldn't dial it up above 40A sustained charge rate.
     
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  15. Randy Spencer

    Randy Spencer Active Member

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    I too charge in just a few hours when I come home so no real need to have a supercharger at home but I am curious what people think the future will be for friends visiting. If a friend drives 150 miles to come visit, they will not want to stay for too many hours as they will need to drive that same amount back. They will need to charge and charging while they wait will be cheaper (for future cars) and save them time compared to stopping on the road. If I do go for 80 amps will that make much difference in their life?

    -Randy
     
  16. suraj1194

    suraj1194 Member

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    The solution to that is to not make friends who have to drive 150 miles and don't have a SC en route :)

    But seriously, if one's view is that all such special corner cases must be covered, then one should spend for it. But for regular day to day use, I find 48A just fine.
     
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  17. Rocky_H

    Rocky_H Active Member

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    :confused: You think someone would drive 150 miles, which is about 3 hours, stay for just an hour or two and drive back? I would hesitate to use the term "friend" if you're going to be that inhospitable. :rolleyes:
    Why would they not be staying for at least a few hours? And then again, they are coming from 150 miles away, to Alameda California, no less, and they don't have any Superchargers along the route? I concur with @suraj1194 that people seem to sometimes intentionally be trying to find the most obscure and unheard of circumstances to rationalize unneeded high amp charging at home.
     
  18. IT Geek

    IT Geek Member

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    Well, hopefully if I've inspired someone to come 150 miles to see me they'll want to stay more than a few hours before they drive home... :)

    Just yesterday I was looking at the future plans that Tesla has for Superchargers in Michigan. It's rather encouraging that they are planning to put in so many more than what we have right now. If they follow through on what they say they are going to do then I'll be surrounded in every direction by Superchargers within a few years.

    When Livonia, Auburn Hills and St. Clair Shores come online then that would put my house within 20-40 miles of a Supercharger in every direction, even if someone is going East over to Canada.

    upload_2017-4-26_17-20-35.png
     
  19. IT Geek

    IT Geek Member

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    upload_2017-4-27_12-16-16.png

    upload_2017-4-27_12-16-40.png

    All done except for the drywall patching... Finally, home charging. It's a beautiful thing.
     
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  20. jbcarioca

    jbcarioca Active Member

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    When I finally had home charging after four months without I was ecstatic. I travel a lot so my car sat for a month at a time three times without charging. I really disliked that! So, congratulations! I do know how you feel. BTW, I agree with your choice regarding aesthetics, especially since home charging almost never really needs much more than 208/30 to deal with any conditions. It would be nice to have more, more is always better, but often not worth the price.
     
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