Charging curve of Tesla Model Y SR and Performance Impact

What is the charging curve?

To put it briefly, it represents a graphical visualization of how your Electric vehicle charges over time. The process is indicated by a graph following the maximum charge an electric vehicle can process. The charging process for an electric car isn’t as linear as plugging in a charger and gaining immediate top to your battery. It requires time for the chemicals from within the lithium-ion batteries of your car to assimilate the charging. It’s not only limited to electric vehicles but also includes anything supplied by batteries.

The 20% and 80% rule of charging

With every electric vehicle, it remains a staple to follow the 20%-80% rule when charging an EV, but why that number, you may ask? This logic applies to lithium-ion batteries as they are known to work most efficiently within the range of 20%-80% SOC. Consecutively, when charging exceeds 80%, your EV will take considerably longer to reach 100% as the rate changes to preserve its cell life expectancy predictably. Think of it as a room filled with people; the more people that enter, the less space there is for other people to find, making the process slower.

What battery cell does the Tesla Model Y Standard Range have

The Tesla Model Y Standard Range (AWD) was initially developed in Giga, Texas, and it was structurally manufactured to be equipped with a 4680 battery. It is currently however discontinued as it was speculated that Tesla was making room for the ramping up of the second generation 4680 production for its Tesla Cybertruck.

Comparison of Tesla Model Y  charging curve 4680 and 2170 battery cell

 DC Charging with the Tesla SR AWD Model Y (4680 Battery cell)

The 4680 battery cell doesn’t charge well from 0 to 100, following a Level 3 charging rate. The state in which the 4680 tapers through the graph is aggressive and indicates a worse charging curve compared to the 2170.

• The charging of the 4680 doesn’t take advantage of the Supercharger charging power and sustains only 200kW for a brief period until  5% of SOC.
• At only 20% SOC , the power has dropped significantly down to 100kW.
• 0-80% in 43 minutes; battery power has dropped from 50kW to 19kW after making it through 90%.
• Reduces the power charging down to Level 1 charging speeds when charging near a 100% charge capacity. The battery temperature remains at 58 degrees Celsius throughout the charge. The total charge time from 0-100% was recorded as 2 hours for the 4680.

DC Supercharger  comparison (Model Y standard SR vs Model Y Long Range)

The Tesla model equipped with the 2170 battery pack charges faster than the 4680 when pitted against a charge from 10%-80% utilizing a charge from a Supercharger V2 at (150kW DC). The difference in output is tabularized as below:

Tesla Model Y Standard Range – 4680 charging curve rate description

Tesla Model Y Long Range – 2170 charging curve rate description

Charging curve comparison of the 2170 and 4680 (1^st generation) battery cells of the Model Y LR and SR.

• The 4680-equipped Model Y has a smaller cell per-pack battery that, in return, results in a smaller battery capacity.
• The battery pack 2170 has roughly 10-11kWh more cells per pack than the 4680.
• Charges slower than the LFP pack provided by the 2170 battery cell as the charging rate peaks fall short in most of the points as the SOC increase.
• Tesla themselves choose to be conservative with the battery; throttling it allows the consumer to consider the 2170 of the older Tesla to be still viable.

Another chart comparing Power vs SOC on the Model Y batteries shows a worse charging curve than the other battery packs (18650 vs 2170 vs 4680).

• The smaller cells of 18650 used within Tesla’s vehicle can keep cool more quickly due to their smaller individual thermal mass, which translates to less mass to transfer heat through each cell to reach the centre of the cylindrical cells.
• The 4680’s design has a larger dimension to store more energy and utilizes side-cell cooling. However, its form factor change for increased diameter causes an increased electrical resistance that reciprocates a slower charging rate.
• Observing the kW to SOC chart, it was found that the Model Y -4680 dropped from 80kW at 50% and stagnated till it further dropped when reaching 80%.

Do you need to keep an eye on your Tesla charging at all times?

The definite answer is no. Car manufacturers have already implemented an onboard charger to accommodate the vehicle battery. The onboard charger will have a battery management system that intelligently knows when to trickle charge and expedite the charging rate based on how much charge and temperature the battery is currently subjected to.

Removal of feature due to possible battery limitation.

The performance impact of the changes made to the 4680 was realized when Tesla first started delivering its 4680 cell Model Y. It was believed that the upgrade “Acceleration boost” that enabled the Tesla Model Y standard range to shave off 0.6 seconds from its 0-60 mph by the incremental upgrade of 50 HP was wholly removed after 10 days of being available in-app for purchase. Given that the upgrade would’ve made the standard-range Tesla Y faster than the long-range variant at a lower price, with that we could make an educated guess as to why Tesla removed the feature.

How does the charging curve translate to real-life- Performance

Despite the slower charging curve of the 4680 batteries in the Standard Range, users who own the new Tesla Model Y from 2023 were quick to point out that the battery degradation from putting the miles on their Tesla Model Y was pretty much non-existent.

Conclusion

It’s easy to pinpoint the discrepancies in the Tesla Model Y SR -4680 charging curve. Still, it is equally impressive that Tesla is bringing forth a bigger dimension battery, albeit almost on par with the 2170 cells due to its tabless design. It is also expected that the 4680 battery will be improved upon following rumours that the next generation of the 4680 battery will be on the Tesla refresh of the Model Y, Juniper. In essence, Tesla never promised a faster-charging battery during its initial reveal of the 4680 battery but has recently reiterated that cost reductions from ramping up the yield over the 2170 will always remain atop the improvements made for the company.