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Dual Charger setup and Charging outdoor

wwu123

Member
Apr 11, 2017
416
347
Silicon Valley, CA
I'm certain that's not correct.

This is the Model 3 section of the forum, so let's do that one first:
Splitting between the 15 mph and the 22 mph would be about 18.5 mph.

The Model X is a bigger and heavier and less efficient vehicle, so with the same amount of energy will get fewer miles, so it will have to be less than that, not 19.2.
Splitting between 8 mph and 14 mph is 11 mph.

And this is why it's so frustrating that Tesla did this idiotic mistake of releasing the Gen3 wall connector when shared charging was not implemented yet. People are scrounging for used Gen2 wall connectors just to get this basic useful functionality.
It's not correct, I'm certain as well, I just put there simple multiplication for anyone to see and do..:) There are charging efficiency losses, and a 400 w / hr constant electronics overhead, and 3 and Y are not the same, and no exact version of S nor X is exactly 3 mi/hr, and so on. So the ballpark was 19.2 for Model 3, vs the table saying 18.5, I'm surprised it was even that close. Close enough for government work, as they say...

I guess I'm not really sure why the OP dismissed the suggestion of the Tesla Gen2 HPWC's. From what I understand if configured at 40A, it would do exactly what the ClipperCreek does, split it 20A/20A when both cars are calling, and then when one car is done allocate all 40A the the remaining car. It's a "dual charger" that comes in two separate identical boxes. There is even a metal outside pedestal Tesla sells that lets you mount them back-to-back, makes the entire thing like one physical device.
 

af88

Member
Sep 28, 2019
257
37
Cali
With a single HPWC like clipper the install is simple, connect conduit whip to panel or junction box and done. No need to run conduit across the garage.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,660
7,955
Boise, ID
It's not correct, I'm certain as well, I just put there simple multiplication for anyone to see and do..:) There are charging efficiency losses, and a 400 w / hr constant electronics overhead, and 3 and Y are not the same, and no exact version of S nor X is exactly 3 mi/hr, and so on. So the ballpark was 19.2 for Model 3, vs the table saying 18.5, I'm surprised it was even that close. Close enough for government work, as they say...
Oh yeah, I missed that you had switched in that line from doing the calculations from the X to the 3. I thought that said 19.2 for the X, which was way too high. But yeah, that's very close for the 3. My bad.
I guess I'm not really sure why the OP dismissed the suggestion of the Tesla Gen2 HPWC's.
...because Tesla doesn't sell them anymore. Seems like a sensible reason to dismiss it, rather than trying to troll the depths of Ebay and hope to get two working used ones from different people. And the people selling used ones know how in demand they are, so they are charging ticket-scalping prices for them.
 

wwu123

Member
Apr 11, 2017
416
347
Silicon Valley, CA
Oh yeah, I missed that you had switched in that line from doing the calculations from the X to the 3. I thought that said 19.2 for the X, which was way too high. But yeah, that's very close for the 3. My bad.
No worries, got it - your helping out many folks on these forums, esp on electrical issues, is great. The same swag on the X charging was indeed more like 30% off compared to Tesla's charging table.

Funny thing is that table is probably based on the same types of rough calculations, rather than actual field measurements, except they must've further subtracted out some fixed overhead losses. That's why the mi/hr for 48A is not quite 2X the rate for 24A or 3X the rate for 16A. The reason I think they formulated rather than measured for the table is because the Model 3 column IS uniquely exactly proportional to amps, which just can't be true - so I think the table was likely iterated and updated over the years by different Tesla people making different assumptions. But I couldn't back out a fixed overhead number that lined up exactly with the table for the other models.
 

GSP

Member
Supporting Member
Dec 28, 2007
2,575
804
Scheduled Charging, Scheduled Departure only apply to the home location. (You set the home location in the Tesla Navigation system.) My experience with my Model Y and setting the maximum charging amperage is that it must be reset every time you charge if you want other than the maximum charging amperage of the circuit as limited by the EVSE. If you plug in to charge at any other location then Scheduled Charging or Scheduled Departure do not apply to charging at work (for example.)
This is not how it works on my 2015 Model S. I can set the amperage and scheduled time to start charging when at away-from-home locations, and the car remembers these settings the next time I charge at that location. My 2018 Model 3 works the same way.

If you go to a new location, then you will have to enter the amperage and scheduled start time if you don't want to charge immediately at the default amperage.

GSP
 
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captjoemcd

Member
Nov 29, 2019
258
288
California
I sincerely hope you are kidding. Let's put this in some numbers perspective.
1C is considered a pretty reasonable level for charging batteries. For a 75 kWh battery capacity, that would be 75 kW. As I mentioned, people are actually worried about damaging their batteries from home charging and are talking about turning down their home charging speed from 11 kW to something less, like 6 or 7 kW. That is charging coefficients of about 0.09 C to 0.14 C. That's splitting hairs between "extremely low" or "incredibly low".

Sure, technically they are not exactly the same. But you are saying you think that is going to make a significant, measurable difference in the lifetime or degradation rates of the batteries?
Along these lines… wouldn’t immediate, frequent swapping between 200-400kW output (acceleration) and 50-85kW input (regen braking) and back again have way more of an impact on the battery than 7-11kW continuous charge? I’ve been wondering this for quite awhile but haven’t seen an discussion comparing charging to typical driving. I’d think that typical home charging wouldn’t be anywhere in the same ballpark as the demands of typical driving (supercharging being obviously a different level). Of course home charging being for a longer timeframe than regen braking, but at only 10-20% of the power and without the swings between charge and discharge.
 
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NickFie

Member
Sep 28, 2017
550
625
Near Philadelphia, PA
Scheduled Charging, Scheduled Departure only apply to the home location. (You set the home location in the Tesla Navigation system.) My experience with my Model Y and setting the maximum charging amperage is that it must be reset every time you charge if you want other than the maximum charging amperage of the circuit as limited by the EVSE. If you plug in to charge at any other location then Scheduled Charging or Scheduled Departure do not apply to charging at work (for example.)
Tesla vehicle remembers max current for each non-Supercharger location where it has been set.

I’m pretty sure the same applies for scheduled charging. That can be “Start at” or “Depart at”.

We have two Gen 2 HPWC sharing a single 100 Amp circuit. One is on an exterior wall near the driveway - my wife’s preferred spot for her Model 3. The other in the garage - my preferred spot when I get visitation rights for my Model S shared with local daughter’s family.

The two HPWC negotiate power division between attached vehicles. Last night out-of-town daughter and her husband visited with their Y. They took the driveway HPWC and started charging. I drove my wife’s 3 into the garage and plugged in that HPWC. My wife’s car starts charging at 02:30 AM. Both daughter and wife planned early departures.

However, I didn’t have to get up in the middle of the night to swap a single HPWC between vehicles.
 

Sean1

Member
May 12, 2019
74
42
Los Angeles
I just posted my separate dual charger set up if anyone is interested in getting some ideas
 

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