Supercharger charging rate

Supercharger charging rate

While we still have some 120kW SCs, a formula for acceptable charging rate.

Thanks to Bighorn for the formula:

State of Charge (SoC)% + 
Charging Rate (CR)kW =
Supercharger (SC)kW rating  


SoC% + CRkW = SCkW


SCkW - SoC% = CRkW


120kW - 30% = 90kW
120kW - 60% = 60kW
120kW - 90% = 30kW and dropping

If you start with a SoC of less than 10%, you may briefly see the full 120kW, but the rate will quickly decrease. 

Question is - how low is too low? The formula shows what would be an acceptable charging rate. 

If you don't see this value, you're either sharing the charger with another car or you should report the stall as defective. 

If your using stall 6A, make sure there's no one using 6B. It may not be next to you. 

This formula works only with 120kW Superchargers, because the number 100 (%) is close to 120 (kW).
100 is close to 120.

Problem - Bighorn we need a new modified formula for the new 150kW, 250kW, and 75kW Superchargers.

txakoli | May 9, 2019

The formula is valid for 85 kWh batteries; not sure about the 90 and 100 kWh. I believe the taper is different.

The formula is not valid for cold soaked batteries, It'll be valid once the battery warms up.

Bighorn | May 9, 2019

My original formula was SOC + kW = 125 +/- 7. I’ve seen that top rate of 132 rise some over the years to the mid 140s, albeit briefly when first plugging in. In the LR Model 3 and the 100kWh Model S, the sum is in the 160s which is why travel is more efficient and one can achieve better average speeds over time.

I tried to investigate the 150 kW power yesterday along with the battery pre-heating function, but both my cars were charging in the mid 30kWs which made me suspect there’s been some local throttling. Plugshare reviews this week indicate normal charging speeds for others at the same SC. | May 10, 2019

There are a lot of factors in getting the full power. Your current SOC, temp of your battery, size of your battery, if someone is using the companion stall (some locations use dedicated 72 kW stalls), and even the temp of the Supercharger module (if too hot) will throttle the power. I made a couple of taper charts that may, with the latest getting 147 kW in an M3 LR:

Tropopause | May 10, 2019

Any thoughts about this YouTube video?

Two LR Model 3's were Supercharged from 5% to 90%; one with the new 12.2.1 software (150 kW), the other with older software (120 kW). The 150 kW car gets a 7% lead but eventually tapers to a rate which is lower than the 120 kW car. In the end, they tied to 90%. Is this the way Tesla intended this new charging to work? I'm not impressed that the faster charging eventually becomes slower.

inconel | May 10, 2019

I've been wondering about the faster initial charge as well as pre-warming the battery before arriving at a supercharger. With both the battery might get too hot earlier with throttling setting in earlier.
I am sure Tesla has figured out the optimal strategy but it might depend on how high SOC the user wants to go.

ronjolley | May 11, 2019

Bighorn - Apologies for the oversimplification of your formula(s). I hadn't had occurence to observe the evolution of your formulas. 

BTW - my examples were not based on empirical data, but simply numbers passed through the simple formula.

Interesting that someone surmised that my simple formula and examples worked for a 85kW battery when I own a 2014 P85 with AP1.

Primary purpose of my post is my elusive dream for a simple formula to help newbies know when a charging rate (e.g., 60%, 35%) is normal or a reason for concern. 

Perhaps a formula that works for just key SOCs.