We may often encounter lithium iron phosphate batteries in life, but many people may not know much about its depth of discharge, now let’s learn something about the depth of discharge of lithium iron phosphate batteries.
Generally speaking, the depth of discharge of a battery usually refers to its degree of discharge, people are used to express it as a percentage, for example, we often say that the depth of discharge of a battery is 80%. However, a battery can be discharged more than the depth of discharge of this battery, this phrase means that if the depth of discharge of a battery is 70%, but in reality, we can use the degree of discharge can be more than 70%, for example, discharge 80% of the power. But if your battery charge is often below 30%, then your battery may be at risk of damage.
Generally we can do the calculation of lithium iron phosphate discharge depth by measuring the discharge current. For example, we have a 200Ah battery, now we connect this battery to the power supply for 24 minutes, and we find that this battery discharges at a current of 50A. At this point in time we can calculate its depth of discharge by using the following.
Discharge capacity = 50A*24/60h = 20Ah
Depth of discharge of this battery: 20/200*100=10%.
This method of calculating the depth of the battery applies to all batteries.
Most of the time, the battery depth of lithium iron phosphate is not static, and is usually limited by factors such as temperature, length of use, and number of cycles.
3.1 Temperature: As the temperature is too high or too low will affect the charging speed of the battery and the ion transportation inside the battery, and sometimes it will also cause some damage to the battery to a certain extent. This leads to too high or too low depth of discharge of the battery.
3.2 Length of use time: Generally speaking, the longer the length of use of the battery, the more serious the damage to the chemicals inside the battery, and the depth of discharge of the battery will be easy to be abnormal.
3.3 Bad cycle times: Each battery has a bad cycle times, for example, the cycle times of lithium iron phosphate battery is 3000~6000 times. When it reaches the number of cycles, the battery can no longer be used normally. So generally speaking, the more times the battery has been cycled, the more the battery depth will deviate from the normal value.
When the environmental temperature of lithium iron phosphate battery is too high, the chemical reaction inside the battery will accelerate, resulting in faster battery discharge. Although the discharge rate of the battery will be slowed down in a lower temperature environment, it is not good for the health of the battery. Therefore, when storing or using, we can try to keep it at about 20℃~25℃.
In many cases we may accidentally open the switch of power equipment, which will cause unnecessary power consumption. Moreover, when too many power devices are connected, the discharge rate of the battery will be higher than the maximum discharge rate of the battery, which will also lead to abnormal discharge of the battery.
It is worth mentioning that the depth of discharge of lithium iron phosphate batteries is more stable compared to lead-acid batteries and other batteries, which is one of the reasons why people have begun to use lithium iron phosphate batteries instead of lead-acid batteries.
