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Time Remaining vs. kW rate

camalaio

Active Member
May 28, 2019
1,483
2,098
Vernon, BC, Canada
Hey folks,

Sitting a charging station near Ucluelet. There's a temporary 25kW L3 station here. Plugging into it, the car reports either 4 or 5 kW and 2h45m remaining. Plugging into the 6 kW L2 shows 5h30m remaining.

Which one should I trust? Surely it can't be charging faster with lower kW?

I have a theory: Perhaps the station is delivering about 10kW or so, but as it's L3 the car is actively cooling the battery which maybe takes about 5kW? But on the L2 the car is choosing not to cool as aggressively and gets most of the power. Based on this, maybe time remaining is based on gross power input rather than net power input. Does anyone know if this is a reasonable theory?
 

ucmndd

Well-Known Member
Mar 10, 2016
6,674
12,534
California
The only “L3” stations your car can use are superchargers or Chademo stations with the Chademo adapter. What is this charger you’re using, and how?
 

camalaio

Active Member
May 28, 2019
1,483
2,098
Vernon, BC, Canada
The only “L3” stations your car can use are superchargers or Chademo stations with the Chademo adapter. What is this charger you’re using, and how?

Using the CHAdeMO adapter, it's far more prevalent than Superchargers around here. It's a Delta unit run by BC Hydro, just connect and push a button to start charging. Unit displays no errors or issues.
 

JayNJ

Member
Jul 13, 2018
243
121
New Jersey
Hey folks,

Sitting a charging station near Ucluelet. There's a temporary 25kW L3 station here. Plugging into it, the car reports either 4 or 5 kW and 2h45m remaining. Plugging into the 6 kW L2 shows 5h30m remaining.

Which one should I trust? Surely it can't be charging faster with lower kW?

I have a theory: Perhaps the station is delivering about 10kW or so, but as it's L3 the car is actively cooling the battery which maybe takes about 5kW? But on the L2 the car is choosing not to cool as aggressively and gets most of the power. Based on this, maybe time remaining is based on gross power input rather than net power input. Does anyone know if this is a reasonable theory?

I would trust what the car says for time. It may not have ramped up yet. How long did you plug it into to get the kW reading?
 

RandyS

Fan of Elon
Jul 8, 2012
715
931
San Diego
When the Model 3 starting being able to use the Chademo adapter, I tried mine and got different readings on the Model 3 screen vs. the screen of the DC FC. I believe the DC FC screen since I have used it before with other cars (and it displayed amp and volt values that seemed reasonable). As I recall, the difference was about 15 to 20 kW. I haven't tried it a second time at another location, but I would say with that one observation that the Model 3 screen is under reporting the power level for some reason when using the Chademo adapter...
 
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camalaio

Active Member
May 28, 2019
1,483
2,098
Vernon, BC, Canada
Based on further experience with this charger, "time remaining" is definitely reporting too short of time though I'm not sure why. Verified plugging into the L2 gives more battery percentage than this L3 over an hour.

Whatever goes on under the hood to consume power for all the whines and whirrs and thunks may be part of why it's reporting this way. These things occur on the L3 station (much like supercharging) but not the L2.

I would trust what the car says for time. It may not have ramped up yet. How long did you plug it into to get the kW reading?

It was plugged in for over an hour. Not sure what percentage was added, but it also said +4kWh. The "Time Remaining" also decreases at about half the rate of reality based on a second attempt. (e.g. as soon as it says 2h05m remaining, it takes 10 minutes for it to show 2h00m remaining, and this trend continues).

When the Model 3 starting being able to use the Chademo adapter, I tried mine and got different readings on the Model 3 screen vs. the screen of the DC FC. I believe the DC FC screen since I have used it before with other cars (and it displayed amp and volt values that seemed reasonable). As I recall, the difference was about 15 to 20 kW. I haven't tried it a second time at another location, but I would say with that one observation that the Model 3 screen is under reporting the power level for some reason when using the Chademo adapter...

Interesting. The station itself will deliver more power than reaches your battery I would assume (charging losses, battery cooling, HVAC if in the car, etc.). 15kW is a very large difference though!
 

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