Home charging for a 2015 P85D with "dual chargers"?

[bcsteeve]

I just made a deal on a 2015 P85D with dual chargers. I'm not really sure what that means. Can someone shed some light not only on what they are, but what kind of electrical should I be installing in my garage? Is it still a normal 220V socket or am I going to have to install two or what? Sorry if its a dumb question. Tesla doesn't archive info for older models on its site so I can't just rtfm (well, maybe I can... still Googling. Figured I'd ask in the meantime).

 

[P85DEE]

The dual chargers in the car, or on board the car, will allow you to use at your home, a choice of either the:

Model S/X Corded Mobile Connector which comes with the car.

Model S/X Corded Mobile Connector

Which will charge the car at about 26 miles per hour.

OR the

Model S/X/3 Wall Connector

Model S/X Wall Connector

Which will allow you to charge at home at about 52 miles per hour.

Charging | Tesla

 

[HankLloydRight]

But for the first option you only need a 50 amp circuit to charge at 40 amps.... The second option you'd need a 100 amp circuit to charge at 80 amps (or less). For most people, the 40 amp option works just fine.

 

[Rockster]

As an owner of a dual charger P85, I can offer that I love being able to charge at 80 amps. I routinely charge at about half of that; however, on those occasions when I need to charge at twice the rate, it's fantastically convenient. Examples include:

• One of us driving all around the metroplex all day and returning home in the evening with the car nearly empty on a day when we've planned to leave town that evening (say, to drive down to Austin). During the 90 minutes it takes to pack suitcases and prep the house, the car is ready to go again.
• Oops! We only charged to 50% last night because we thought we were just going to be at home or traveling very little the next day but when we awakened we decided to take a 100 mile trip for a spontaneous adventure. 80 amps to the rescue. By the time we finish breakfast, we've added enough padding to make the trip possible.
• Travelers passing through town finding us on Plugshare can charge at twice the rate (if their car is configured to do so). Granted, folks coming by the house to charge is less common because of the increasing number of Superchargers available.

In short, even though you'll likely charge at 40 amps or so most of the time, when you really need or want to charge twice as fast, it's great. In over 80,000 miles driven, I've never once regretted the extra money spent to hook up a 100 amp wall charger. Plus, my mobile charger just lives in my trunk, so I never worry about forgetting it when I go out of town.

 

[bcsteeve]

Wait, you choose what rate to charge at? Or did I misunderstand that?

TBH, I'm not sure if 100A is possible in my house. Seems to me the whole house has 150A service (I'll double check). If it means thousands of dollars in electrical upgrades to the house, I'll pass. I think what I'll probably do is a DIY NEMA 14-50 and I'm in for under $60. See how that goes. If I find I'm forgetting the cable or it is charging too slow, I'll take another look.

Regardless, tyvm for the responses.

 

[HankLloydRight]

Wait, you choose what rate to charge at? Or did I misunderstand that?

With either the UMC or HPWC, you can dial down the charging amperage in the car -- up to the max rate supplied to the UMC (40 amps) or HPWC (up to 80 amps, depending on what service feeds the HPWC).

For instance, you can still get a HPWC and connect it to a 50amp circuit. It doesn't require an 100 amp circuit. In one of my garages, I only have 30 amp service and a NEMA 14-30 socket. I build a 14-50 adapter cable, and use my HPWC to charge at 24 amps.

 

[bcsteeve]

It chooses 24A in that case? It maxes out at 24A? Or you specify 24A?

 

[HankLloydRight]

It chooses 24A in that case? It maxes out at 24A? Or you specify 24A?

It's a little tricky. With a HPWC, there are DIP switches to set the charge amperage.

But if you're using a UMC in the same scenario.. it would be plugged into a NEMA 14-50 outlet (which then goes into a 14-30 adapter cable), the UMC thinks it can charge at 40 amps, but that would quickly blow the circuit breaker. So I have to manually set it to 24 amps. But the car uses GPS to remember the charge settings at that location, so it always uses 24 amps in that garage.

 

[bcsteeve]

Ahh, cool. Thanks.

 

[fsch]

See here how to fabricate and wire home-made adaptors, at your own risks.

Alternatively, you can buy the adapter from Tesla (if this specific adapter is available, which is often not the case) in which case the adapter "tells" the car what is the limit.

I fabricated a few adaptors myself. The most useful one in my case is the 240V/20A air conditioner plug (NEMA 6-20). I've installed such plugs at a couple of places where we often go (mother-in-law, brother) on their garage heating circuit. (Of course, the heating has to be turned off during that time!) I limit manually the current to 80% of the circuit, so I get 16 A, and our MS85 charges from empty to full in ~15h. Since we usually arrive their for dinner and sleep there, we stay long enough to fully charge before leaving after breakfast. I also made an adaptor to plug in the welder plug of an uncle, and a couple of others. So 95% of the time, we refuel while we sleep (which can hardly be done with an ICE), and seldomly go to superchargers or other chargers. I would say this is my main discovery: with an electric car, you seldomly need to go to the equivalent of a fueling station. Just need access to 240V.

That being said, although it's a supplementary cost, it's very practical to have the HPWC right there at hand for everyday use at home, rather than getting the UMC in trunk of the car, connecting it, and putting it back in the car in the morning. As mentioned, the HPWC can be configures to different max current depending on how full is your electric box.

And I also have a double charger but used it maybe 2-3 times in 2 years, and could have done otherwise. Except in very few occasions, you either want to supercharge, or you have the night to charge. And in the few occasions you need something in-between, 80A chargers are rarely available at these locations. At least this is my experience.

 

[bcsteeve]

I get that the HPWC would be convenient. But... not sure its worth the cost.

NEMA 14-50 runs me about $60 if I DIY. Maybe $400 if I pay an electrician and bother with permits. Done.
HPWC at 80A is going to cost me ~$3000 for service upgrade + $400 for install + $650 for the charger itself. > $4k

I just don't see the value there, personally. I might change my mind if the 40A becomes inconvenient But probably the most inconvenient thing is moving the charger. Can't I just buy a 2nd UMC? Or a wall unit ($633) powered @ 40A?

 

[fsch]

You can have the HPWC at 40A or 30A if you want, if your electric box is already near saturation, and you can probably install it yourself. My point was just that I find it much more practical for everyday use. But you have to buy thing, probably around 500$.

 

[bcsteeve]

Sure, yeah I got your point. Totally with you on the practical in terms of convenience. 100%. Just not in terms of cost to run it at 80A. Since it is cheaper than the UMC, I think what I'll probably do is just DIY the NEMA 14-50 and see how it goes with the UMC and then down the road buy a HPWC (probably used for a couple hundred) if it turns out the UMC becomes a problem.

I *imagine* - though I have no practical experience to draw from - that in my situation I will never or extremely rarely use the UMC other than to plug in at home. I don't think I'll even bother keeping it in the car (I will at first!). The routes I take either have SC on the way, or else I'm back home well before the range is up.

But I basically know nothing really, so I'm just trying to soak up the options.

Thanks for your help.

 

[P85DEE]

Sure, yeah I got your point. Totally with you on the practical in terms of convenience. 100%. Just not in terms of cost to run it at 80A. Since it is cheaper than the UMC, I think what I'll probably do is just DIY the NEMA 14-50 and see how it goes with the UMC and then down the road buy a HPWC (probably used for a couple hundred) if it turns out the UMC becomes a problem.

I *imagine* - though I have no practical experience to draw from - that in my situation I will never or extremely rarely use the UMC other than to plug in at home. I don't think I'll even bother keeping it in the car (I will at first!). The routes I take either have SC on the way, or else I'm back home well before the range is up.

But I basically know nothing really, so I'm just trying to soak up the options.

Thanks for your help.

Looking at the cost difference that you cite above, it appears that it would be hard to justify the HPWC.

However one advantage that your dual on board chargers allow you is the potential for faster destination charging.

Destination Charging | Tesla

 

[bcsteeve]

The biggest part of the cost is upgrading service to the house, because here all our services are run underground. I have 125A service to the house and roughly a 70A peak draw. Adding 80A means upgrading to 200A service and that's a big job and comes with very high permitting costs. And no way to avoid the permits for that job and no way at all I'd consider DIY

Honestly, if I found I *needed* the 80A at home, I'd probably go looking for another address that already has 200A service lol. Seems easier.

 

[Rockster]

Wait, you choose what rate to charge at? Or did I misunderstand that?

TBH, I'm not sure if 100A is possible in my house. Seems to me the whole house has 150A service (I'll double check). If it means thousands of dollars in electrical upgrades to the house, I'll pass. I think what I'll probably do is a DIY NEMA 14-50 and I'm in for under $60. See how that goes. If I find I'm forgetting the cable or it is charging too slow, I'll take another look.

Regardless, tyvm for the responses.

There are two choices to be made:

1. When installing the wall charger you set its DIP switch to tell it the capacity of the circuit on which it has been installed. This way, the wall charger knows its max charge rate. (Obviously, you want to make sure the DIP switch setting is correct for the circuit and that the circuit has the correct breaker and wiring and the panel can support that load, etc.). In my case, the DIP switch specifies that the charger is on a 100 amp circuit.
   
2. From within the car, you can select any amperage from a minimum of 12 amps up to the maximum amperage that the DIP switch setting specifies. (As you can readily infer, I can select anywhere from 12 amps to 80 amps.) I'm pretty sure this setting is geocached and therein remembered by the car for that location.

 

[gregd]

The biggest part of the cost is upgrading service to the house, because here all our services are run underground. I have 125A service to the house and roughly a 70A peak draw. Adding 80A means upgrading to 200A service and that's a big job and comes with very high permitting costs. And no way to avoid the permits for that job and no way at all I'd consider DIY

Honestly, if I found I *needed* the 80A at home, I'd probably go looking for another address that already has 200A service lol. Seems easier.

You probably already checked, but if not, have the power company come out and review the actual power lines going to your meter. I also had an underground fed 125A service, a full panel, and wanted to add a 50A circuit for the car. It turned out that for whatever reason, the lines running to my meter were good for 225 A, so the upgrade to 200A, while still not cheap, was done without bothering the shrubs or gophers.

Also, I found a local electrician who would let me contribute my unskilled labor to the project, under his review of course, to save money.

But, yes, a full 80 amps for the car is probably overkill for most. I ran off the dryer plug - 24 amp charging - for 2 years, with no problems. What pushed me into the upgrade was an expiring tax credit, and the discovery that my panel was of a type that was discontinued years ago because they tended to "fail", as in "catch fire".

 

[AB4EJ]

I've been satisfied with charging at 40 amps using NEMA 14-50. In fact, unless I need to go from almost exhausted to 100% overnight, I set it to charge at 20A using control in vehicle. (Higher charging amps dissipate much more of your energy as heat, because heat generation is proportional to the square of the current). So lower charging amps is a little more efficient, if it provides the charge you need in the time you need it.

 

[henderrj]

I don't know what it's like up there in BC but here in Puget Sound PSE gives a $500 rebate for any EV charger. So that makes it a brain-dead decision. You could always take it out and take it with you if you moved houses. I have dual Chargers in mine and absolutely appreciate the ability to charge at 60 miles an hour. (The new ones, as I understand it, only charges 52 miles an hour.) I DIY'd the installation of my hvwc as well.

 

[Brass Guy]

I rarely unplug my UMC. In 4 years, maybe 6 times. Put in your 14-50 and call it done, that's what I did.
I just came back from a road trip (eclipse). I packed my UMC. I didn't need it, except to show it to a curious onlooker.