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beeeerock
Active Member
Oh, I completely understand the issue... I just don't like it! Every time I see this I ponder how nice it would be if the internal chargers would allow more amperage to make up for the lower voltage so that E x I could come closer to the kW rating of the charger.
I agree. If we could control the charge rate by kW instead of by amps, it might be possible. Problem is, the EVSE is limited by amps (it's own capacity and the circuit it's connected to). A 32 amp EVSE @ 240 volts = 7.68 kW but only 6.656 kW @ 208 volts. Even if the car were somehow able to "ask" for 7.68 kW, the EVSE couldn't deliver it because it is capped at 32 amps (in my example here) regardless of voltage.
beeeerock
Active Member
I was thinking more in terms of my own situation... a single charger. It's frustrating to connect to a Sun Country unit that's apparently good for 69 amps and have my system max out at less that it would if based on kW's... 40 amps at 240 volts at home would be 46 amps on a 208 circuit. Every little bit helps, when you're cooling your heels waiting for enough added range to make it to the next stop.
I ordered a second charger last night, so some of this will go away for me, but still, it would be nice to allow more current since you can't even get a car from the factory with the second charger now anyway...
Right. I saw your post about the second charger.
One weird thing I've noticed with SCH-100 chargers (I have 2 at my office): For some reason, my car will max out at 79 amps. If I set it to 80, as soon as I connect, it drops to 79 and I can't dial it up any further. I asked SCH and ClipperCreek about it and they assumed it was some sort of "rounding error" by the car when it sees the pilot signal from the EVSE. Funny thing, though... when I had a loaner P85 a while back, it would see and charge at the full 80 amps. If I connect my car to a HPWC, I can and do see the full 80 amps, so it's got to be something to do with my older Model S and these SCH/ClipperCreek units. (One amp is not going to make any appreciable difference, but I do find it odd).
I wonder if the HPWCs send some sort of signatory signal such that the car recognizes it's connected to a HPWC and not just a "generic" EVSE, a signal that the the Clipper Creeks would be missing. Since Tesla makes the car & the EVSE in the case of the HPWC, I can see them deciding to somehow embed an extra bit somewhere that only matters to them.
beeeerock
Active Member
That is weird. Having seen an Add Energie unit with problems cause the car to pull less current, I have to wonder if there is something subtle in the wiring that caused the Tesla to decide 79 is just the right number to meet some sort of internally-determined threshold value.
I guess we can't blame the conversion from Canadian to American amps in this case, like 3.78 litres vs. 4.54 litres - to a gallon - LOL!
The J1772 standard is pretty simple-minded. The station sends a square wave to the car, and the duty cycle determines the available charge current. The car has to measure that. Tesla seems to come out 1A low on J1772 stations, on both Roadster and Model S... but not on their own stations, so it's probably in the realm of "interpreting the standard".
Yeah, except that the loaner I had actually did set and charge at the full 80 amps (on my SCH-100 station). I'm guessing there is some subtle hardware difference on newer cars because both it and my car were running the same firmware.
Hmm... you'd think they'd measure the waveform in firmware.
Okay let's just put it down to "rounding error".
Okay let's just put it down to "rounding error".
Phillip L
Gas Passer
"I find that PlugShare is an excellent app for finding charging stations. There are quite a number in the Waterloo Region. And they do have a Tesla-specific version that works quite well in the Model S browser."
Do you have to have a second login for the Tesla Plugshare app because I have not been able to sign in with my regular Plugshare login?
Do you have to have a second login for the Tesla Plugshare app because I have not been able to sign in with my regular Plugshare login?
That's odd. Nope, for me my regular PlugShare credentials work fine. I believe you can still use the app without logging in (you can for sure with the "regular" web app) but you won't be able to check in and you won't be able to contact home users sharing their chargers.
Actually, I don't have an account, I just press on "Skip registration" in the car's browser, and I can check in just fine (including entering current and voltage) without an account. It shows up without a name, of course, but it at least says you were in a Model S.
This is useful, for example, to simply report that a site that had not been working is in fact working again. Red Dog Inn | Terrace Bay, ON | Electric Car Charging Station | PlugShare (That was me.
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