I just installed a second HPWC in my garage and was a bit surprised by how they work. When either is connected alone I get 72A and charge rate of about 50 - 55 miles / hr. When I connect both and they are both charging I get 40A each and about 25 - 27 miles / hr charge rate. That all seems fine and makes sense. What surprised me was when one car completes charging and is no longer charging, but still connected the other charger only increases to about 45 Amps and up to about 30-32 miles/hr charge rate. I was actually expecting the remaining charger that was still charging to move up to 72A and full charge rate.
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pilotSteve
Active Member
I had thought that originally, but the second car, that was still charging, had about 60% charge, and in addition the amperage still did not increase, which I would expect would even if the charge rate was not as high as the car reaches full charge.
I see people have this misunderstanding of tapering frequently. You're thinking of it tapering down from Supercharger power levels. Yes, it will come down from 100kW to 60, 50, etc. but that is still several times more power than home charging. It's based on with this % full in the battery, here is how much power it can take. If the power source is already low enough that it's far below that tapering power level, then it's not going to be restricted. So tapering is almost never seen from home charging because 240V at 40A is 10kW. The tapering won't get down to the 10kW level until about 97-98%, which most people don't do at home very often.
henderrj
Active Member
So, has Tesla Service responded to this? I too hope to have two Tesla's and was going to have another HPWC installed. This would make me wonder how to do it.
Daniel 74
Active Member
I have the same experience with our two HPWC. If one car is connected and charging, it gets full power (3 x 16A in our case). If both cars are connected and charging, the power is split to 3 x 8A per car/charger. If one of the two cars is ready charging (but still connected), the other car does not get the full 3 x 16A but only 3 x 10A.
I mentioned this a year ago to the Amsterdam service center, but never got a reply.
Is there anyone who sees a different behaviour with two HPWC in a master/slave setting?
I mentioned this a year ago to the Amsterdam service center, but never got a reply.
Is there anyone who sees a different behaviour with two HPWC in a master/slave setting?
henderrj
Active Member
That is exactly the situation that I would like to test. Perhaps some other local Tesla owner could accommodate you? I'd offer but it's a long drive from Seattle!
Hooking up with another Tesla owner is on my ToDo list. It's not urgent, though, as my Model 3 isn't arriving until Nov - January (and I suspect the actual delivery is going to be a bit later than that). Plus, I'm in the midst of some home remodeling that includes getting the garage ready for Tesla solar/powerwall, which I'm hoping occurs before the end of the year.
I thought I read that any connected car will be reserved 6 amps because that is the J1772 minimum pilot signal. In the European case like @Daniel 74 this is somewhat unfortunate because it's 3 * 6 amps. However, that is definitely not what the OP is observing.
This isn't that kind of forum.
I would also expect the remaining to go to the still charging car.
What happens if you unplug the charged car? Does it then pop up to full charge like it did if you just started with a single car? There isn't a taper with home charging.
I did hear rumors of 6A reserved if a car is plugged in... but not sure.
Yes, just tested this a few minutes ago, if I unplug charged car it goes to what used to be full when I had only 1 charger (72 Amps), but charges at a slightly lower rate (49 m/hr instead of 54-55 m/hr when I had one charger).
Ah, you're misunderstanding what those numbers are. The amps and kilowatts are an instantaneous reading. The miles per hour number is an average over the whole charging session. It's just a Tesla quirk that has always been that way. So it is averaging together the earlier period of time when it was getting something like 30A with the last couple of minutes when it went up to 72A. So yes, of course it is going to display a lower level of miles per hour than if it had been at 72A the whole time.
The "earlier" period was less than a couple of minutes, and I checked it over a period of 2 hours. Seems like a high impact for that short of a time, but maybe.
As an aside the lower m/hr is true if I only plug one of the cars in by itself as well.
As an aside the lower m/hr is true if I only plug one of the cars in by itself as well.
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