Model 3 Charging Curve

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NOGA$4ME

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#81
OK, that was the missing piece of my puzzle (the Mobile connector contains a EVSE).
But how does the Mobile Connector know how many amps to tell the car to draw (considering that it can be plugged into multiple outlet types)? If it's based on the type of adapter that's connected to the mobile connector, that implies that it can't take full advantage of many 20A 120V outlets (vs 15 amp). Or are 20 amp outlets different?
I suspect (but don't know for sure) that when you use different adapters with different plug types (that support different max currents) that there is some kind of hardware jumper or something that tells the connector to only offer a certain max current to the car.
 

NOGA$4ME

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#83
Electricians sometimes use 15 amp outlets On 20 amp/12 gauge circuits. This is safe but lazy.
Mostly safe. If the outlet itself starts to melt over 15A, and you have a broken device you plug into it that has a short and draws 20A, the breaker won't trip and yet the outlet will overheat. Granted, there are safety margins, and we're talking about a very specific failure mode that is highly unlikely, but the risk is still technically there.
 

ummgood

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#84
Electricians sometimes use 15 amp outlets On 20 amp/12 gauge circuits. This is safe but lazy.
Right but using a 20 Amp draw on all 15 Amp blade receptacles is not safe so it makes sense that Tesla would limit the 15 Amp adapter to 15 Amps * 80%. That way someone who doesn't know any better won't plug it into a circuit that is truly 15 Amp and turn their car up to 20 because they can.

Technically the breaker should be limited to the end connector. For example my wiring can support 60 Amp on my NEMA 14-50 install. But because the plug itself is 50 Amp that is the breaker they installed. Later if I wanted to switch to a TWC with 48 Amp I would have to upgrade my breaker to a 60 Amp one which would still be safe at that point. An electrician who installs a 15 amp blade plug should not put a 20 amp breaker on that circuit.
 

Thom Moore

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#86
The 8.5 cord is probably best for inside a garage and the 24 foot cord is better for outside applications. Although I would imagine that there will be some charge loss due the extra 15.5 feet.
We got the longer cable a year ago and have much appreciated it since getting our Model 3 and now having two ports to feed, it's nice to have a longer cable to get to the second car.
 

Thom Moore

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#87
It was still >100kW by 35%- IIRC when I unplugged at around 60% it was down to ~65kW. The dropoff was fairly linear once I hit 50%.
We made our first real road trip this weekend and got it down to 27% in Aberdeen MD. We had 115 kW initially, and it held above 100 kW up to 50%, at which point we had enough to get home.

So all's well and it appears Tesla has it right. Apparently, a battery may not warm up much (?) during a 30 mile drive...
 

PNWmisty

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#88
We got the longer cable a year ago and have much appreciated it since getting our Model 3 and now having two ports to feed, it's nice to have a longer cable to get to the second car.
I ordered the HP Wall Connector today from the Tesla Site. When I logged in I still wasn't sure what cord length I wanted. I clicked the 24' option and the price remained at $500. So I put it in my cart. And the price never increased. Maybe Tesla needs to hire some better website developers?
 
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#89
I ordered the HP Wall Connector today from the Tesla Site. When I logged in I still wasn't sure what cord length I wanted. I clicked the 24' option and the price remained at $500. So I put it in my cart. And the price never increased. Maybe Tesla needs to hire some better website developers?
Shhh!!!!
 

NOGA$4ME

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#90
I ordered the HP Wall Connector today from the Tesla Site. When I logged in I still wasn't sure what cord length I wanted. I clicked the 24' option and the price remained at $500. So I put it in my cart. And the price never increased. Maybe Tesla needs to hire some better website developers?
When I got my first Aerovironment EVSE there was no price difference between the 25' cable and the shorter one (can't remember how short, maybe 10'?) They probably just built the cost of the longer cable into the price (or the markup was just so huge that the cost difference between cable lengths was insignificant)

Either way, you'll be glad you have the longer cable. I can almost guarantee you'll need to use it at some point and you can always use cable management to "shorten" it when you don't.
 

PNWmisty

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#91
Either way, you'll be glad you have the longer cable. I can almost guarantee you'll need to use it at some point and you can always use cable management to "shorten" it when you don't.
Yeah, I think so. And the way electric cars are going, it won't be long before guests will want to use it and we won't have to shuffle cars around.
 

NOGA$4ME

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#95
Pardon me...

I haven't been monitoring this message forum for some time now.
What does the "SoC [%]" refer to in the table posted two messages up-page from here?
(i.e.: GregRF, Today at 1:14 PM)
State of Charge %

Basically the chart is showing that as the battery is getting fuller, the charge rate (power going into the battery) tapers off to less than 20kW when the battery is at 95% full.

It shows very good charge rate (116-117kW) until the battery is at 50% SOC at which point the taper begins.
 

tivoboy

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#96
Here is some cool data on the Model 3 supercharging curve:
View attachment 10064
source
I'd love to have a copy of this graph with some TIME estimates between SoC levels. It would seem that the best thing to do from a max charging efficiency standpoint would be to get to an SC at about 15% remaining, and then charge to 65-70% for max efficiency in charging.
 

PNWmisty

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#97
State of Charge %

Basically the chart is showing that as the battery is getting fuller, the charge rate (power going into the battery) tapers off to less than 20kW when the battery is at 95% full.

It shows very good charge rate (116-117kW) until the battery is at 50% SOC at which point the taper begins.
I bet the charge rate varies quite a bit depending upon the temperature of the battery.
 

NOGA$4ME

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#98
I bet the charge rate varies quite a bit depending upon the temperature of the battery.
True, although that in turn will depend on how effective the Model 3's cooling system is as well.

Off topic, but eventually I would like to see the ultra fast chargers (350kW class) have a coolant connector in addition to electrical connector to provide off-board cooling capacity to the battery while charging at high rates so as to allow for more reasonably sized on-board cooling systems and not tap power that could otherwise go into the battery.
 

PNWmisty

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#99
Off topic, but eventually I would like to see the ultra fast chargers (350kW class) have a coolant connector in addition to electrical connector to provide off-board cooling capacity to the battery while charging at high rates so as to allow for more reasonably sized on-board cooling systems and not tap power that could otherwise go into the battery.
That would add a lot of complexity compared to simply providing a few more kW than the battery needed for charging purposes.
 

NOGA$4ME

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That would add a lot of complexity compared to simply providing a few more kW than the battery needed for charging purposes.
Yes, and no...they are already looking at running coolant down the length of the cable from the charging unit to the nozzle, even at 120kW power levels. So the complexity on the EVSE side is almost a done deal.

But yes, a few additional valves would be needed to patch in the connector's coolant loop into the battery's coolant loop (and bypass the car's built in one).

If you assume 90% charging efficiency, at 120kW you have 12kW of heat to dissipate in the vehicle...no small feat.. Pump the charge rate up to 350kW, and you have an additional 23kW to deal with...about tripling the size of the cooling system, which aside from being heavy, would also require a very large radiator(s). If it was me, I'd probably take the added complexity of some valves over having to engineer (and fit into the car) the much larger battery cooling system (that really, is only going to be used while the car is sitting still and charging).