Best is 50 % of central SOC level of  SOC for example 25% to 75% of Battery state is best to use for charging and discharging. The Charging tends to slow out side SOC range of  [20->80%] to protect Ev battery’s internal ambience, health and longer life. Such slow tending behavior of battery is caused by controlling through BMS( Battery Management System). The BMS are programmed in such a way to keep Longer life and safe temperature (25 Deg.), other ambience , control & operate cooling system, regulate High equal voltage, discharge current in equal & sync manner working of each individual cell, avoid any rigorous effect on Battery placed inside the EV. Almost all (except Tesla Model-x & High Brand E Car) have  fast charging acceptance  SOC within range of  [20->80%] SOC. With a Slow charger / On Board charger, (different specs for each EV car) one can Charge an EV from 0 % to 100% level. In A urgent situation when Ev have lowest level say 5%, one have to Juice up EV by a slow charger up to 20% then use Fast Charger for upto 80%, then Again use Slow charger for next session beyond to 80% to till 100% SOC.

What is a Battery’s Life Cycle?

There are only so many times a battery can undergo the process of discharging and recharging before it completely breaks down. Cycle life refers to how many complete charges and discharges a rechargeable battery can undergo before it will no longer hold a charge. A charging cycle is completed when a battery goes from completely charged to completely discharged. Therefore, discharging a battery to 50% and then charging it back up to 100% would only be counted as 1/2 of a single battery cycle.A LiFePO4 battery will last an impressive 2,000 to 5,000 cycles. Keep in mind that the estimated number of charging cycles does not always indicate how long a battery will last since there are other factors at work, including what temperatures the battery is exposed to and how well it is maintained.

It is good to do charge EV Battery in between 30->80% SOC  (Charge-Discharge)

The 30-80% SoC > < DoD (state of charge >< Depth of Discharge)  rule refers to the idea that you should try to keep your battery charged between 30% and 80%, not allowing it to drop below 30% and not charging it above 80%. This range is generally safe & prudent rule of acceptance, to keep the protection circuit alive Allowing a lithium-ion battery to drop below 30% can shorten its lifespan. If you charge a lithium-ion battery to 100%, it will stop charging, however, if it stays connected to the charger, it will use a little bit of energy every time it drops down to 99% in trying to get it back up to 100%. Doing this raises the battery’s temperature, which also shortens a battery’s lifespan. That’s why with lithium-ion batteries, it’s best not to charge them all the way up to 100%.

How to keep Ev Battery’s longer Life Cycle?

• Keep a battery at a moderate temperature. At a temperature 25 to 30Deg. Battery remains safe and sound. As food stays fresher when refrigerated, so also does cool temperature protect the battery by reducing internal corrosion, also known as parasitic reactions on the electrolyte and electrodes.

• Avoid deep cycling. Operate drive EV in mid SoC of 30–80%. Each cycle wears the battery down by a small amount and a partial discharge is better than a full discharge. When possible, only apply a full discharge to calibrate a smart battery and to prevent “memory” on nickel-based batteries. Li-ion is maintenance-free and the battery lasts longest when operating between 30 and 80 percent SoC.

• Avoid harsh use/abuse. Like a machine that wears down quicker under strenuous work, so also is a battery stressed by harsh discharges and rapid charges. Use cells that are optimized for the power and energy requirements as per application and increase that pack size to minimize load-related stresses.
• Avoid ultra-fast charge. Charge Li-ion Energy Cells at less than 1C (below rated Ah); Power Cells are more rugged and can be charged and discharged at a higher rate. till Date year 2022 , Except two or three EV car model , No one accept Ultra Fast from a Charger of 350Kwh. While All Big EV Cars accept 250 KWH Fast Charger, like E Tron, Jaguar I Pace, Merc EQC while  and TESLA accept From its Supercharger V3 250 For its All mOdel.
• Store Li-ion at partial charge in a cool place. The worst combination is high voltage and elevated temperature. Store Li-ion at approximately 50 percent SoC.

• Do not Discharge rigorous till Lower level: Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. Prevent full cycles by applying some charges after a full discharge to keep the protection circuit alive The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life.

• Best way to charge: Partial and random charge is fine. Does not need full charge. Lower voltage limit preferred. Keep battery cool while charging( although BMS also automatically this as per pre programmed, still one can also take  precaution  to keep( park while charge) Ev in open air shaded ,Cooler place/ area .

Take on Fast Charging  of   TESLA ( Model  X ) (10 -> 80%)   &   Tata Nexon (20-> 80%) 

Rapid charging enables longer journeys by adding as much range as possible in the shortest amount of time. Charging power will decrease significantly after 80% state-of-charge has been reached. A typical rapid charge therefore rarely exceeds 80% SoC. The rapid charge rate of an EV depends on the charger used and the maximum charging power the EV can handle. The table below shows all details for rapid charging the Tesla Model X Performance.

EV CharZo’s Take on Specific EV  like TESLA & Mid Size Segment Of EV Car TATA & Hyndai < Mahindra & MG ( TESLA Model X Fast Charging  (10 -> 80%) Model 3 ) Fast Charging  (20 -> 80%) India ‘s Mid Size Ev  like Tata Nexon , MG eZS , Hyundai Kona, Mahindra XUV400   (as on 2022) accept Fast Charging in the range Between  (20 -> 80%) SOC