SoC stands for State of Charge, which is the amount of stored energy in the battery. For example, if you have an 80% charge, you have an 80% SoC.
SoC is not the total potential capacity of the battery; it merely signifies the energy in the battery relative to its capacity. A 20% SoC means the battery is 20% charged and a 0% SoC means the vehicle is fully discharged.
We measure SoC in all batteries as a percentage. If you have an iPhone or Android phone, you can set it to display the percentage. Your electric vehicle will also display your remaining battery as a percentage and calculate your range.
Battery health, charge times and SoC
When charging your electric vehicle, your charger – whether it is a public charger or home charger – will refer to the SoC with estimated charge times.
Most EV manufacturers recommended charging an electric car to 80% SoC and recharging when it drops to around 20%.
In our article about how long EV batteries last, we revealed that a 20-80% charge demonstrates the best capacity maintenance over a battery’s lifespan. This is based on a study of 6,000 EV batteries by GEOTAB .
The reason a 20-80% charge is better for the battery versus a 5-80% or 0-100% charge is that it produces less heat and reduces the charge cycle time.
When charging in public, you will also notice charge times drop off a cliff after 80% – this is because DC rapid chargers cut the power output at 80% to a much slower rate to protect the charger from heat.
For example, Car Magazine found that the Polestar 2 needs 36 minutes to charge from 10 to 80% at 150kW, but the last 20% takes another 87 minutes.
Summing up
- SoC stands for State of Charge
- SoC is the amount of stored energy in the battery relative to its capacity
- A 70% charge means you have a 70% SoC
- To preserve battery health in the long run, charging to 80% SoC is recommended.
Happy charging!
