How to keep your electric car’s battery fit if you don’t move it for weeks on end? While some electric drivers don’t pay attention to their vehicle for a long period of time, others diligently charge it full every day. But neither the one nor the other do it right, on the contrary: they all damage the battery of their e-car. Learn more about the basics of battery technology and get tips on how to increase the life of your e-car battery in this article.
Should you charge your vehicle during an extended standby period? How does that affect the e-car battery?
The monthly self-discharge rate for lithium-ion batteries is typically around two percent; however, the battery in an e-car tends to discharge faster because of the vehicle’s electronics.
Example: If a Nissan Leaf is not moved for a long period of time, the battery loses approx. 15 kilometers of range per month . There are far more electronics in a Tesla Model S, which is why the vehicle can be charged up to 15 kilometers of range per day can be forfeited (assuming the Tesla Model S is in the default “standby mode” and not completely switched off).
So you shouldn’t neglect your electric car even during breaks in driving. But by the same token, you should never charge your electric vehicle to 100 percent capacity. Then the cell is under high voltage and the electrolytes degrade the cathode or positive terminal in the battery.
What is the optimal battery charge level?
The truth lies just above the middle : Ideally, the state of charge of the electric car battery is between 80 and 50 percent (Not to be confused with the ideal range for best driving range, which is between 80 and 20 percent). A state of charge of 80 percent results in a voltage so low that the electrolyte does not degrade over several weeks. At the same time, a state of charge of 50 percent is still high enough to reduce the risk of overdischarge when the battery is not used for a long time.
With certain e-cars, you simply configure the charging limits on the dashboard or via web portals. But what if the car doesn’t offer such a feature? Then stop the Battery charge level Manually, as soon as the desired state of charge is reached.
But in doing so, you don’t have to stand next to your car and stare at the battery gauge. Using the formula described below, determine when to start and stop charging:
Take, for example, a 40-kWh battery pack, where the state of charge of the E-car battery is currently 30 percent (d. h. 12 kWh). You want to charge it to 80 percent (d. h. 32 kWh) charge. Let’s assume that your e-car is equipped with a built-in 11-kW charger and you have connected it to an 11-kW charging station.
Proper charging can greatly increase the capacity of the electric car battery. Photo: Bloomberg via Getty Images
The formula for calculating is:
Charging time (hours) = Required current / Charging power
so = [32 – 12 kWh] / 11 kW = 1.81 (1 hour 48 minutes)
If you use the 11 kW charger with a Battery Charge Level of 30 percent and disconnect it from the charging station after 1 hour and 48.6 minutes, the battery of the e-car be charged to about 80 percent.
Please note that the above formula only gives you a rough estimate of the charging time required. The formula does not guarantee a state of charge of exactly 80 percent, because the charging time depends on other factors, such as temperature, SoC (State of Charge, dt. State of charge), SoH (State of Health , dt. general battery condition), age of the Electric car battery and type of technology.
What is the impact on battery technology if you simply leave your e-car plugged in (even beyond a SoC of 80 percent)?
There is some discussion regarding the proper charging strategy if you want to leave the charger plugged in for an extended period of time. It makes sense to check the SoC of the car battery at least once a week and charge the vehicle when necessary (when the value drops below 50 percent).
There is nothing wrong with leaving your car permanently plugged in as long as you follow the 80 percent rule. That is, your vehicle must first be able to set the charge limit at 80 percent. The Battery management system (BMS) of your electric car should regulate the charging behavior , so that the battery is charged only when necessary and not always further.
Also note that the Car 12-volt auxiliary battery – As it is also used, for example, in a gasoline or diesel car to power the headlights, windshield wipers and infotainment systems – normally only charged when the traction battery is active. That is, it is charged when the electric vehicle is either fully turned on and ready to drive or when the car is charging. Considering this, it is important that regularly the car is charged or the engine is turned on.
The conclusion to the optimal charging of the electric car battery:
How should you choose with regard to the Battery state of charge behave?