The Impact of Deep Discharge and Full Discharge on EV Batteries and the Best Charging Suggestions
The discharge amount of EV batteries affects their lifespan. Deep discharge to 20%~30% can occasionally activate the battery, but long-term discharge is detrimental and can lead to faster aging of the battery. Avoid over-discharging your device frequently, that is, fully discharge it. The best charging advice is not to wait until the battery is almost gone before charging, and over - charge it. The middle range is the most suitable for optimal battery health.
Deep Discharge and Full Discharge: More Different Than You Think
(I) Deep discharge: the challenge of moderate power
Deep discharge is like a long-distance runner who is almost exhausted but still gritting his teeth to keep going. When the battery of an EV is only about 20% to 30% left, just like the runner, it is on the verge of collapse. This is deep discharge. Although it can be sustained occasionally, but if it's a constant state, the battery's going to be in big trouble.
From the perspective of the chemical reaction inside the battery, deep discharge is like pouring fuel on a fire. Especially at the low power stage, the polarization phenomenon of the battery becomes more and more obvious.Polarization is like a traffic jam. In a battery, it is when there is too much charge on the electrode, which "blocks" the road, causing the electrode potential to be abnormal and the internal resistance of the battery to increase. As a result, when the battery is charging, it will generate more heat due to the "traffic jam", and the battery will not be so happy.
However, appropriate deep discharge can actually be benefinicial. Just as moderate exercise can exercise the body, occasional deep discharge can activate the active substances of the battery plate and have a certain positive effect on maintaining the performance of the plate material. If a battery is used frequently until it is almost out of power, just like a person who is too tired, the battery's internal components will age and degrade super fast, and the battery will become difficult to use, the performance will further worsen, resulting in use inconvenience.
(II) Full discharge: the ultimate challenge of the battery
Complete discharge means using up all the battery power, just like when a cell phone is turned off automatically. At this time, the battery voltage will become very low. For example, for lithium-ion batteries, the voltage drops to about 2.5 to 3 volts, which means that the battery is running out of power and you need to find a charger immediately.
Completely discharging a battery is hazardous, just like being extremely tired can make a person sick. When a battery is dead, bad reactions can occur inside it, which can cause some of the battery parts to deform and damage the battery. Especially for lithium-ion batteries, if the power is discharged too cleanly, something like thorns (lithium dendrites) may grow on the negative electrode. These thorns are very dangerous and may pierce the membrane inside the battery, causing the battery to short-circuit itself. In this case, the battery's performance will decline, its lifespan will be shortened, and in more severe situations, it may even pose safety risks.
If the battery is completely dead and left uncharged, it will be like a person who is extremely hungry but has nothing to eat. The battery will also "starve to death". Under this circumstance, the parts inside the battery will malfunction, and charging and discharging will fail. The battery capacity will drop substantially, and the battery may even be completely broken and become unusable.
The best charging power range for EVs: the golden rule for caring for batteries
(I) Daily use: smart choice of 20% - 80% power range
When driving an EV, keeping the battery power between 20% and 80% is like a "comfortable nest" for the battery. If the charge is too high or too low, the materials inside the battery will become like fragile building blocks and easily break.
When the battery power is below 20%, the negative electrode of the battery will collapse like too many things piled on it; when the battery power is full, the positive electrode will also deform, making the battery less durable. Keeping the power between 20% and 80% is like adding an extra layer of protection to the battery. This practice not only extends the battery's lifespan but also ensures its optimal performance over time, allowing it to serve you more effectively for a longer period.
Charging in this power range is not only good for the battery (because it charges quickly), but also safe and can make the battery last longer. Moreover, the battery in this power range is like a steady stream of water, which can steadily provide power to the vehicle, allowing it to run steadily and far.
(II) Long-distance travel: 30% - 90% power range endurance guarantee
When traveling long distances, EVs must be fully charged, 30% to 90% of the power is suitable. This is like going on an adventure and bringing enough dried food in case of any problems along the way, such as not being able to find food (charging stations) or having to take a long detour.
A battery charged to 90% can run dozens more kilometers than 80%, just like bringing more snacks on the road, making you feel more at ease. For example, an EV can run 500 kilometers with a full charge, 400 kilometers with 80% power, and 450 kilometers with 90% power. The extra 50 kilometers may be of great help when driving long distances.
Although charging to 100% will allow the car to travel the farthest, the charging will slow down when it is almost full, just like eating slower when you are almost full, to protect the battery. Therefore, charging to 90% is ideal as it not only secures a long range, you also don’t have to wait too long to charge, which makes more efficient mobility.
(III) Long-term storage: "Hibernation" mode at about 50% power
If an EV needs to be parked for a long time, it is wise to charge the battery to about 50%. This power level is like setting a "hibernation" mode for the battery. In this state, the battery self-discharges relatively slowly, just like entering a low-energy standby state.
At the same time, this can also prevent the battery from experiencing performance degradation due to excessive or low power during long-term storage. If the battery is stored with too high a power level, it is like an over-inflated balloon, which may cause safety hazards such as battery bulging; while if the battery is stored with too low a power level, it is like the battery entering a "starving" state, which may cause the battery to run out of power, unable to charge normally the next time it is used, or a significant decrease in capacity.
It is crucial for EV users to understand the difference between deep discharge, full discharge, and the optimal charging power range for EVs. This can not only extend the service life of the battery, but also ensure that EVs can perform optimally in various usage scenarios, allowing better protection of the battery, the core component, while enjoying the environmental protection and convenience brought by EVs.
