Why can I only get 65kW when Tesla states it has 120Kw

[bd7349]

I've been wondering about this. The extra heat to warm the battery will come from energy stored in the battery. If the driver has SoC to waste then fine, but I at least visit a Supercharger when my SoC is low. I'm imagining that in most of my use cases the option will refuse to operate.

Perhaps it makes more sense to spend the first couple of minutes at the Supercharger heating up the battery.

Elon explained this in a few tweets. See here: Elon Musk on Twitter and here: Elon Musk on Twitter

Basically, since the Model 3 heats the battery via heat from the motors instead of a dedicated battery heater, it'll be able to heat the battery quickly while driving by routing the heated coolant from the motors to the battery. So energy use will be low, but it should be able to heat the pack pretty quickly via motor heat (at least that's what I'm assuming based off his tweets).

 

[MasterC17]

Pro Tip: If you want to Supercharge fast when it's cold outside, do a few foot-to-the-floor "pulls" to heat up the battery prior to plugging in. Either way, there is a direct correlation between battery temperature and Supercharging speed. People assume because it's 60f outside that the battery is "warm". It is not. These batteries are happiest around 100-110f and it can take a long time to get that hot.

Additionally, as others have stated, Supercharging speed starts to taper around 50%.

The whole point of Superchargers is to fast-charge during trips. So if you arrive after a long first-leg with 20% SOC or less, than you will likely receive the full charge speed.

People driving 10 miles, plugging in with 60% SOC and then complaining they're not getting the advertised speed are using them wrong and don't understand how the car works.

 

[tccartier]

I headed to supercharge at Pleasant Prarie, Wisconsin tonight. The map told me that it can deliver 120kW Max. Yet my car, Model 3 is only pulling 62kW. I am the only one charging and the battery would be warm, as I drove 45 mins to get here and it is 44 degrees outside.

Can someone please explain? Am I missing something, is the map wrong?

Images show the map view (I am the one car occupying the stall) and the charge throughput
View attachment 385899 View attachment 385900

As others have noted. Your battery is a huge thermal Mass it can take many hours driving and perhaps days for your battery to reach ambient air temperatures if left on its own. That would be like expecting a glacier to melt in one hour because you moved it into 100 degree Fahrenheit air temperatures.

After you eliminate the obvious such as maybe switching charger stalls to see if you get a different result then more than likely you're just dealing with a cold soaked battery.

 

[Uncle Paul]

I think that Tesla's ability to add a warming cycle to existing cars, prior to supercharging is spectacular.

A gift to the owners that nobody expected.

 

[mswlogo]

My thought as well.

And if the entire pack does not have to be heated then why wouldn't the charge rate jump after a short while on today's system ?

I think it has to do with allocated slots/banks/modules (what ever they call them). It doesn't seem to reevaluate the number of slots it could use, as it goes. I think that's why folks say, changing stalls sometimes works. If they changed to the "same" stall, it would probably work just as often In other words charge for a little bit, stop charging, unplug, wait a few minutes, plug in and it might now meet conditions AT THE START for more slots/banks/modules and charge faster. But if your SOC is high (like around 50%) to begin with, you'll rarely see 120 kW. It seems to happily drop slots/banks/modules on fly, but I've never seen it add them (sudden jump up in kW in the middle of a charge, unless you start over).

 

[SageBrush]

Basically, since the Model 3 heats the battery via heat from the motors instead of a dedicated battery heater, it'll be able to heat the battery quickly while driving by routing the heated coolant from the motors to the battery. So energy use will be low, but it should be able to heat the pack pretty quickly via motor heat (at least that's what I'm assuming based off his tweets).

The motor is about 96% efficient. If we figure an average 10 kW pull from the battery then 400 watts is re-routed from the motors to battery heating. Call it 24 kJ per minute.

The heat capacity of a Li-X pack is around 850 - 900 Joules/Kg/C, so a 500 Kg pack requires ~ 437 kJ to raise the temperature one Centigrade.

All in, 20 minutes of motor waste heat to raise the pack 1 C
If whatever Tesla is doing actually works, it is not simply heating the entire pack with only motor waste heat.

 

[sreams]

I headed to supercharge at Pleasant Prarie, Wisconsin tonight. The map told me that it can deliver 120kW Max. Yet my car, Model 3 is only pulling 62kW. I am the only one charging and the battery would be warm, as I drove 45 mins to get here and it is 44 degrees outside.

Can someone please explain? Am I missing something, is the map wrong?

Images show the map view (I am the one car occupying the stall) and the charge throughput
View attachment 385899 View attachment 385900

Did anybody ask if the other Supercharger of the pair was occupied? If you were connected to Supercharger 3A, and another car was connected to 3B, you share the circuit with the other car. So that could contribute as well.