22 Years' Battery Customization
May 10, 2022 Pageview：1280
For DC (Direct Current) power required in power plants, lead-acid batteries are used. They are stated to be a popular device to store electric energy. However, they occupy lots of space to enhance energy storage. On the other hand, lithium-ion batteries tend to have much higher energy density. They are designed to store much more energy when compared to other batteries available in the market. To calculate stationary lithium-ion battery capacity, it is essential to consider a few factors.
Competitive research combined with consistent development efforts has been going on a global scale. This has helped in the development of high performance and high capacity ESSs (energy storage systems. Since lithium-ion batteries were invented in 1991, these are used widely among energy storage devices. Previously, portable electronic devices used it. But in recent times, ESS application can be noticed in renewable energy plants and electric vehicles. To size lithium-ion stationary batteries, industrial standards are under development.
Lithium Ion Battery Minimum Voltage
Lithium-ion batteries comprise of cells that employ lithium intercalation compounds. These are present as negative and positive materials. lithium cobalt oxide (LCO or LiCoO2, lithium nickel-manganese-cobalt oxide (NMC or LiNiMnCoO2, manganese oxide (LMO or LiMn2O4, lithium nickel-cobalt-aluminum oxide (LiNiCoAlO2), etc. is used. Different manufacturers produce different shapes and sizes based on market needs. Generally, a single cell operates in 2.5 to 4.2 V range. Output voltage of lithium-ion battery varies during discharging. The nominal voltage is considered to be the voltage measured when 50% of total energy is discharged by the battery. This is dependent upon 0.2 C discharge rates. Battery energy is based on product capacity and voltage. Hence, there is obtained high energy density battery from a large capacity and high voltage material.
It is possible to customize Lithium-ion batteries to ensure right performance, fit and size. Such batteries do have higher Energy Density (Size to weight ratio). Their nominal per cell voltage is about 3.7 V. the battery pack uses cells in series and may have voltage in 3.7 V steps. For instance, 3 cells are used in Lithium-ion batteries to offer 11.1 V batteries. Again, 4 cells are designed to offer 14.8 V batteries or with 10 cells, it is possible to derive 37 V batteries.
Lithium Ion Battery Discharge Voltage
The maximum discharge rate of Lithium-Ion is 2C while of Lithium-Polymer is at 3C. A few Lithium-Polymer cell selections have discharge rates that are more than 30C rate. Many want to know how far can Lithium-Ion are discharged and if it is really safe to charge the discharged LiIon. Getting precise answers can be fairly difficult. Not much is published about it even by the leading manufacturers. Remember, LiIon is not merely LiIon. Rather, diverse chemistries are present, but with similar, however, not of equal specifications. But then how to measure cut-off discharge voltage? Discharging below 3.6 V is not preferred. The specifications usually state 3.0 or even lower. Then why stop here. It is mainly to do with how voltage is measured. Generally, voltage is measured by taking battery out of the device. This means battery has to be unloaded.
For example, discharge cell with 2A to 2.5 V. On stopping, voltage jumps to about 3.3 V. It also jumps quite fast. For voltage t reach 3.1 V from 2.5 V, it takes just about 12 seconds. This means, if battery is taken out and measured, 2.5 V will never be viewed.
Hence, how far the voltage tends to jump is based upon discharge current. Smaller jump will be derived with a lower current as well as on battery chemistry. Different voltage jumps can be experienced by different chemistries. This means, by taking battery out from the device, voltage is measured. However, correct indication cannot be derived of minimum voltage that is discharged by the battery.
Therefore with above voltage jump, it can be tough to know the exact battery voltage present especially when the device is on. A better and safe way will be to assume of it being empty when unloaded voltage is found to be below some value. For a few batteries, 3.6 V will be fine. However, most modern cells will allow going much lower.
How low can you discharge a lithium-ion battery?
You may want to know how far it is possible to discharge batteries especially during normal use. Presently, the common values are found to be 2.5 V and 2.75 V. Such values are termed to be the lowest voltage allowed on battery to reach its full lifetime. For normal usage, to discharge battery, it is considered to be the lowest value. However, this voltage does not include current. Therefore, the limit can be stated to be not something that can be only discharged at high currents. Rather, discharge is allowed to this specification at very low current. As load gets removed, battery is likely to recover to above the specified voltage.
How low voltage can be stated to be safe to recharge? Avoid charging cell under 1.0 V. The minimum voltage is prescribed as 1.5 V. It is somewhat below 1 V and 2.3 V. It tends to cover different chemistries and brands. Pre-charging is considered to be another vital detail. At full current, battery is not to be charged if voltage is low. There should be used a reduced current. As the battery gets discharged to this particular low voltage, it is likely to lose some lifetime and capacity. Therefore, highly discharged batteries are better not charged. This is because at low voltages, chemistry breaks down, depending on the amount of chemistry that has degraded the battery. If charged, chances of battery explosion are very high.
Conclusion
You need to be equipped with the right information concerning Lithium-Ion battery cutoff voltage. Do get to know the minimum voltage as well as discharge voltage. It will allow you to use the charge and discharge the battery safely without facing any unwanted hassles at any level. Lithium-ion batteries are great to use provided you are aware of the dos and don’ts surrounding its usage.
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