Lithium-ion Battery: The Ideal Solution for Inverter/UPS Applications

What are lithium-ion batteries for inverters/UPS?

Lithium-ion Battery: The Ideal Solution for Storage applications like Inverter/UPS Applications. A lithium-ion battery is rechargeable and uses lithium ions as the primary charge carrier. They are becoming increasingly popular in storage applications like inverters/UPS due to several advantages over traditional lead-acid batteries.

• Lithium-ion batteries are rechargeable batteries used in inverters/UPS and specially made for deep discharge. The Lithium-ion battery comes in C1 capacity, which makes it compatible with Inverter/UPS, as the Lead Acid batteries come in C20 capacity, which was initially created for automobile applications to start the vehicles. The industry has to make minor changes to use for deep discharge applications. The Inverter/UPS need continuous current discharge for extended periods, so they need Deep Discharge batteries.
• Lead-acid batteries were never successful in deep discharge operations when the loads were higher. If we needed to run the air conditioners or motors, the inverter needed more batteries in series to run the capacity loads, such as motors, air conditioner systems, or heavy machinery. The Lead Acid batteries failed faster, and backup time limitations were there whenever they are used for higher load applications. After the launch of lithium-ion batteries and the improvement in the technology of Lithium-ion batteries its very clear now that Lead Acid batteries will be going to be the story of past in Storage applications.

The Challenges faced by Lead Acid batteries:

The 12V Lead Acid battery block: The Lead-Acid battery comes in a 12V block with a maximum capacity of 200 Ah, which is one of the significant challenges when running higher capacity loads as you need to install many batteries in series to achieve the load. In this 12V block, six cells in series need to be equalized over a period, which is impossible because these cells do not have a battery equalizer inside the battery. When the lead acid battery plates are made, there is no way one can check each plate’s capacity and voltage, making it very vulnerable when all these plates are joined. The battery is ready for the charge as each plate’s voltage and capacity are slightly different, which becomes a major failure problem. Life is limited because when the Lead Acid battery is charged and discharged, the difference of voltage and IR value of each plate keeps increasing, which makes one of the cells overcharged, and the whole battery needs to be replaced. The consistent capacity in each 12 Volt battery is impossible as plate making cannot be controlled. Even though 2V cells come in higher capacity but making them equalized have the similar challenge and cost will be higher than the Lithium-ion battery.

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  Tubular Lead Acid battery has 6 cells welded from inside

  

  Each lithium-ion cell capacity is matched.

  Now if we see in the Lithium-ion battery making process then we see that each cell is checked for the capacity and IR matching so that there is no variation in backup time and each battery made has the similar IR value of cell which increases the life of the cell and on top of it the BMS is installed to equalize the cells in case they get de equalized. So, the perfection of the battery is guaranteed. There is a single battery for any capacity we want to design as the cell chosen for the purpose and the BMS is defined for the higher voltage has no limit in terms of capacity and life of the battery.

Lithium-ion Battery: The Ideal Solution for Inverter/UPS Applications

• The space required: This battery bank requires enormous space, making it almost impossible to keep in homes and offices.
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  Multiple lead Acid battery bank

  

  Large capacity Lithium-ion battery bank which can run 100 KVA load.

  The Lithium Battery bank can be made of any capacity and can be kept in such a small place compared to Lead Acid battery bank sizing and there cannot be any comparison in space taken by the Lead Acid battery bank.

• The capacity: Lead-acid batteries come in C20 capacity, which is one of the significant challenges. When heavy loads are run, a higher discharge current is drawn from these batteries, which reduces the capacity of lead-acid batteries tremendously. The backup time is reduced, and sometimes, the battery goes into deep discharge. So, if we see this comparison chart than we realize we need almost half the size of the Lithium battery if the load is 500 Watt run on 12 V Lithium-ion battery Vs Tubular Lead Acid battery. Some people say this term of Depth of Discharge, but the real term should be the capacity to measure in terms of C1 and C20.

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  150Ah 12V lead Acid battery backup on different loads.

• Balancing of batteries in Series: When the batteries are used in series, the balancing of voltages becomes one of the significant challenges, and one or two batteries get overcharged and replacing the whole battery bank is not possible. Hence, the user tries to change one or two batteries, which creates the cascading problems of mismatching between the Lead Acid batteries.
• Where as the BMS is installed in the Lithium-ion battery bank which keeps equalizing ach cell in the Lithium ion battery bank.
• The Maintenance: The Lead Acid batteries need constant watering to refill the distilled water regularly. If the load is higher, which takes more discharge current from the battery, then the water refilling interval decreases, and frequent watering of the battery is required. The battery bank needs to be cleaned. in the Lithium-ion batteries there is no maintenance is required whatsoever and they are totally maintenance free.

Lithium-ion Battery: The Ideal Solution for Storage applications like Inverter/UPS Applications

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  Tubular battery12V water topping

• The Complicated Charger Required: The Lead Acid batteries require multiple stage charging. The battery can’t be charged in a single stage because gravity is to be made, making the battery charge rather than the voltage. Even if the proper voltage is made in a lead acid battery, gravity is not made, and the lead acid battery is not 100% charged. So, to make the proper gravity in the battery, the charger needs to have different stages like bulk or boost, absorption, float, and trickle charging, which is a significant waste of energy.
• In case of Lithium-ion battery bank the simple charging is required to charge the battery and there is no trickle charging is required because the self-discharge of the Lithium battery is one tenth of the Lead Acid battery.

Lithium-ion Battery: The Ideal Solution for Inverter/UPS Applications

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  3-stage Charging graph of Lead Acid battery.

• The Temperature: the lead Acid battery needs different charging voltages to charge to make the proper gravity at various temperatures. The Inverter/UPS needs an ATC feature on the charger. Automatic temperature compensation feature to charge the lead Acid battery. The lead acid battery needs structured charging for different temperature conditions. ATC Charging

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  ATC chart for Tubular battery

• Pollution: The biggest challenge is that the Lead Acid battery produces Lead fumes, which harm human consumption and the environment.

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  The Lithium Battery Technology is going to change the Battery Storage Solutions.

• Wastage of Power during Charging: Lead-acid batteries need charging in different stages to charge completely, and after getting 100% charged, they need constant Trickle charging, which consumes a lot of power and is a big waste of power.
• Time of charging: Since the Lead Acid battery is an old technology, it needs to be charged slowly; otherwise, the battery plates will be hardened, the water will evaporate, and the life of the battery will be compromised. So, a lead acid battery is charged by 10% of its capacity, so generally, it takes 12 to 15 hours to charge the battery.
• The Lithium-ion battery can be charged faster as they can take more than 50% charge capacity so they can be charged in two hours. The new type of chemistries is available in the Lithium-ion battery chemistry where they can be charged in 10 minutes as well. As the whole world is working on new materials for the Lithium-ion batteries to make them safer and better in applications.
• Storage Time: the self-discharge of the Lead Acid batteries is very high compared to the lead Acid batteries and the Lithium batteries can be kept for more than one year without use and without charging whereas the Lead Acid batteries get calcification if they are stored without charge for 6 months or so.