Slow DCFC charging

[tnugentfl]

I've been charging a lot on Superchargers lately and after the boost period of around 160 to 170 kW, the charging speed drops to around 94 kW, and hold until close to 80 percent. I thought the steady charge speed used to hold around 120 kW on EA. Does anyone have any info on this?

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[TomB985]

I've been charging a lot on Superchargers lately and after the boost period of around 160 to 170 kW, the charging speed drops to around 94 kW, and hold until close to 80 percent. I thought the steady charge speed used to hold around 120 kW on EA. Does anyone have any info on this?

I think it’s a temperature thing unrelated to the charger.

I monitor temps with an OBD scan tool, and I noticed when towing in warmer weather that my battery can stay as high as 85-90º on trips. I get the boost for ten minutes, but the battery is up to 95-97º, and I only see ~100 kW from there. I’ll consistently hold 140 kW in cooler weather when my battery is under 90º F.

Summer is on the way and temperatures are climbing, so I think you’re seeing temp throttling that you don’t see in cooler weather.

 

[TheBigBezo]

I never used an obd scanner but my road trips last summer in triple digit weather I felt like I was for sure seeing lower steady state speeds across multiple charging sessions. Temp gage was almost always on the high side. I don't have max tow and was traveling with my dog so I had to leave the cabin AC going.

 

[tnugentfl]

I guess it could be the temps. I have max tow, I wonder if speed would improve with A/C off.

 

[TaxmanHog]

I guess it could be the temps. I have max tow, I wonder if speed would improve with A/C off.

Probably not, Lightnings with Max Tow have an AC Compressor dedicated to powertrain thermal management.

Your cabin HVAC running only slightly reduces net energy stored on the traction battery

 

[ctuan13]

Probably not, Lightnings with Max Tow have an AC Compressor dedicated to powertrain thermal management.

Your cabin HVAC running only slightly reduces net energy stored on the traction battery

I thought it was only a separate refrigerant loop. Is there actually a second compressor?

 

[tnugentfl]

Yes, max tow has a second compressor.

 

[hturnerfamily]

the 'second' compressor is also SOLELY for the Max Tow package cooling, and an extra collant loop, for the Battery only. The 'primary' compressor is then ONLY for air conditioning for the cab.

 

[RocketGhost]

I thought it was only a separate refrigerant loop. Is there actually a second compressor?

With Max Tow there are two compressors, one solely for cabin a/c, and the other solely for powertrain. There are two coolant (not refrigerant) loops in the powertrain circuit: one for motors/inverters/etc. and the other for just the battery. Both coolant loops go through a single heat exchanger (chiller) that transfers heat from the coolant to the refrigerant.

Without max tow there's one compressor that does it all.

 

[Nuts&volts]

Have a ‘23 XLT SR. I don’t fast charge all that often, really only on long trips. Just about every charger that I use on the road has been peaking at about 150kw (even on 350kw chargers), but the last couple trips I’ve taken the charger peaks out at 100kw. I know I have gotten updates on the truck and the app in the intervening time.
I haven’t had any extreme weather, cold or hot. Has anyone else experienced this? What could be the cause / solution?

 

[jetfixr1]

What was your SOC when you started and did you precondition? Also, some chargers are balanced. Additional users may decrease rate.

 

[tnugentfl]

I've been doing a bunch more DCFC today and yesterday. There is no doubt the Superchargers are slower during the steady state charge period. Many different chargers, getting 92 to 94 kW. Using EA and Circle K getting 104 to 110 kW. Only thing I can figure is Tesla NACS w/adapter is getting warm and charger is derating. Not dogging the Superchargers, as reliability and locations are awesome.

 

[luebri]

I've been doing a bunch more DCFC today and yesterday. There is no doubt the Superchargers are slower during the steady state charge period. Many different chargers, getting 92 to 94 kW. Using EA and Circle K getting 104 to 110 kW. Only thing I can figure is Tesla NACS w/adapter is getting warm and charger is derating. Not dogging the Superchargers, as reliability and locations are awesome.

For what its worth... primarily to satiate my own curiosity I put together a quick (non-scientific) spreadsheet comparing the overall time benefit to Long DCFC sessions with less stops vs Short DCFC (Boost) sessions with more stops. Basically I picked an arbitrary amount of KWH that one might need for a road trip. I used 150 as to me that combined with departing with a full battery pack at departure is a healthy ~ 450 mile road road trip.

With Supercharger access this is now an actual legitimate discussion as you can typically be confident another DCFC will be available not too far down the road.

My conclusion, if my charge rate drops below 120kw I am unplugging. Above that I'll probably stick it out.

 

[RickLightning]

Which adapter are you using?

I noted some charging speeds when using Tesla Superchargers on my end of March / beginning of April trip.

25% SOC- 164.52kW
63% SOC - 128.4kW
33.5% SOC - 164.92kW
42% SOC - 167.65kW
57% SOC - 131.75kW at EA, not Tesla
38% SOC - 163.58kW
61%SOC - 150.95kW
65% SOC - 132.96kW
52% SOC - 176.48kW, climbed to 178.33
71.5% SOC - 116.54kW

 

[carys98]

I've been doing a bunch more DCFC today and yesterday. There is no doubt the Superchargers are slower during the steady state charge period. Many different chargers, getting 92 to 94 kW. Using EA and Circle K getting 104 to 110 kW. Only thing I can figure is Tesla NACS w/adapter is getting warm and charger is derating. Not dogging the Superchargers, as reliability and locations are awesome.

Have you tried the Tesla wet rag trick?
https://insideevs.com/news/718718/tesla-supercharger-wet-towel-improve-charging-speed/

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