Today I took my November-2022 Fremont-built Tesla Model 3 RWD to a Supercharger for the very first time. I tried to set conditions for getting the maximum initial charging rate, wanting to log the charging rate vs. elapsed time. To that end I did enough driving earlier in the week to get the state of charge down to about 33%, and planned a three-stop itinerary meant to arrive at a 250 kW V3 Supercharge at between 10 and 20% State of Charge with a warm battery.
I observed battery cell temperature as reported by ScanMyTesla, and the state of charge, activity in preconditioning, and predicted SOC when finally reaching the Supercharger as shown on the screen of the Tesla. After the fact I looked at the reported usage of battery heating by segment as reported on TeslaFi
First leg:
I started at 34% SOC, cell temp of 73.0, and a forecast SC arrival SOC of 21%. The first leg is modestly downhill, so very little power was burned.
I ended this segment at 35% SCO, cell temp of 75.2. I never noticed a preconditioning for Supercharging annunciation on the screen, and later TeslaFi reported no use of the battery heater in this 19 minute 8-mile segment.
Second leg:
After spending 8 minutes buying coffee I set off to a tiny shop dealing in propane things, to turn in two 20 pound tanks with expired certification. This leg was mostly on urban interstate, and took 18 minutes to travel 16.5 miles. I noticed the preconditioning for SC annuncation as soon as I started the leg, and throughout the leg. TeslaFi affirms that the battery heater was on for 100% of this segment. The travel plus the heating ran my SOC down to 25%, my cell temp up to 105F, and my predicted arrival at SC SOC down to 19%.
Third leg:
I falsified the earlier arrival at SC estimates by changing my route to add appreciable mileage. I hoped to arrive with a low teens SOC and fully preconditioned battery. However, I never noticed the preconditioning prompt on this entire leg. TeslaFi says battery heat was on for 6% of this leg. The battery temperature gently declined, starting at 105 and ending at 102. Actual SOC on arrival was 14%.
Supercharging:
I saw 170 kW when I first got a view of the screen after plugging in the car. At that point cell temp was still 102.
In another minute and a half the charging rate had dropped to 135 kW, cell was up to 109F, SOC 21%. About this time, or perhaps a little later I noticed a text annunciation that The battery was too cold for best charging and heat was being applied. (Later TeslaFi affirmed that battery heat had been used "for a portion of this charge").
After the fast initial drop, the charging rate descended gently, reaching 99 kW when the SOC got to 57%, by which time the cell temp reading was 127 and the indication that heat was being applied was gone.
Questions of interest:
1. For my LFP battery model 3, is there a target cell temp on arrival at the Supercharger? If so is it the same 120 reported on this forum for the traditional cars.?
2. Why did my heating terminate? It was right around the time the current SOC dropped below 20% with the change from green to orange in the screen SOC indicator.
3. What is the real maximum V3 Supercharging rate for my car? Would I get a higher rate than the one observed by contriving to arrive at 20% SOC with the preconditioning having reached goal?
4. What governs when preconditioning turns on? Will it look past an indefinite number of intermediate waypoints?
All of this probably belongs as a post on an existing thread but I did not find one to fit. Maybe this thread can be suffered to lived using a focus on LFP supercharging.
I observed battery cell temperature as reported by ScanMyTesla, and the state of charge, activity in preconditioning, and predicted SOC when finally reaching the Supercharger as shown on the screen of the Tesla. After the fact I looked at the reported usage of battery heating by segment as reported on TeslaFi
First leg:
I started at 34% SOC, cell temp of 73.0, and a forecast SC arrival SOC of 21%. The first leg is modestly downhill, so very little power was burned.
I ended this segment at 35% SCO, cell temp of 75.2. I never noticed a preconditioning for Supercharging annunciation on the screen, and later TeslaFi reported no use of the battery heater in this 19 minute 8-mile segment.
Second leg:
After spending 8 minutes buying coffee I set off to a tiny shop dealing in propane things, to turn in two 20 pound tanks with expired certification. This leg was mostly on urban interstate, and took 18 minutes to travel 16.5 miles. I noticed the preconditioning for SC annuncation as soon as I started the leg, and throughout the leg. TeslaFi affirms that the battery heater was on for 100% of this segment. The travel plus the heating ran my SOC down to 25%, my cell temp up to 105F, and my predicted arrival at SC SOC down to 19%.
Third leg:
I falsified the earlier arrival at SC estimates by changing my route to add appreciable mileage. I hoped to arrive with a low teens SOC and fully preconditioned battery. However, I never noticed the preconditioning prompt on this entire leg. TeslaFi says battery heat was on for 6% of this leg. The battery temperature gently declined, starting at 105 and ending at 102. Actual SOC on arrival was 14%.
Supercharging:
I saw 170 kW when I first got a view of the screen after plugging in the car. At that point cell temp was still 102.
In another minute and a half the charging rate had dropped to 135 kW, cell was up to 109F, SOC 21%. About this time, or perhaps a little later I noticed a text annunciation that The battery was too cold for best charging and heat was being applied. (Later TeslaFi affirmed that battery heat had been used "for a portion of this charge").
After the fast initial drop, the charging rate descended gently, reaching 99 kW when the SOC got to 57%, by which time the cell temp reading was 127 and the indication that heat was being applied was gone.
Questions of interest:
1. For my LFP battery model 3, is there a target cell temp on arrival at the Supercharger? If so is it the same 120 reported on this forum for the traditional cars.?
2. Why did my heating terminate? It was right around the time the current SOC dropped below 20% with the change from green to orange in the screen SOC indicator.
3. What is the real maximum V3 Supercharging rate for my car? Would I get a higher rate than the one observed by contriving to arrive at 20% SOC with the preconditioning having reached goal?
4. What governs when preconditioning turns on? Will it look past an indefinite number of intermediate waypoints?
All of this probably belongs as a post on an existing thread but I did not find one to fit. Maybe this thread can be suffered to lived using a focus on LFP supercharging.
