LVC (Low voltage cutoff) and its significance for batteries

During regular use, batteries charge and discharge countless times. A common mistake most users make with their batteries (lead-acid or Li-ion) is overcharging and over-discharging, also known as deep discharge.

Batteries are charged with the help of an inverter/UPS. The manufacturer preprograms these chargers to cut off the charging process once the battery has attained the required voltage level, say 14.4V or any other. Charging the battery beyond this cutoff level overcharges it, which is not suitable for the health and lifespan of the battery.

Frequent overcharging damage the battery; this is why you often see bulged or swollen batteries. To prevent overcharging, manufacturers program the inverters to stop the charging process when the battery is charged to the right voltage level.

While overcharging is terrible for the batteries, over-discharging or deep discharge is equally detrimental to the battery’s health and lifespan. Deep discharge occurs when the entire charge of the battery has been drained.

Similar to the cutoff level specified to prevent overcharging in Lead acid or Lithium-ion batteries, a high-performance UPS/Inverter comes with a voltage cutoff feature to prevent over-discharging.

The purpose of specifying cut-off voltage is to maintain the health of the batteries during discharging. You will know more about this feature and how it helps your battery and UPS/inverter’s performance and life in the below article.

What is a low voltage cutoff?

A battery’s Low voltage cut-off (LVC) is the voltage level at which the charger disconnects the load from the battery. It is when the battery stops powering your fans, lights, refrigerators, and other loads in the house. The function of the cutoff voltage is to prevent the battery from entering the deep discharge stage.

Usually, the low voltage cutoff (LVC) for a 12V battery is 10.5V. It means the battery will stop running the load when it comes down to 10.5 V. This LVC can be set even higher, such as 11V, to improve the battery’s life and reduce all chances of deep discharge. The higher the LVC, the better the battery’s life, whether lithium-ion or Lead acid.

Our Premium range UPS comes with a Safe Discharge or higher LVC feature. A higher voltage cutoff at 11V means the battery will be disconnected from the load as soon as it attains the 11V level instead of the lower value of 10.5V, which is the industry standard right now. Safe discharge means the inverters are programmed with AI to protect your battery by setting a higher LVC, which diminishes the chance of deep discharge.

Benefits of setting a higher LVC for the battery

Low voltage cutoff or safe discharge immensely help increase the health and life of the battery. If there is no over-discharge detection feature, the battery will keep discharging to the level it goes bad completely. The frequent deep discharge decreases your battery’s life considerably.

Some ways it helps the battery include:

Prevents deep-discharge 

Imagine a situation where a low battery disconnects from the load, followed by two or three days of a prolonged power cut. The battery will continue to self-discharge. If it’s LVC is not set at a higher level, say 11V, it will over-discharge, making it impossible for your inverter to recharge.

This is why you see people taking their batteries to electricians to get them charged with a special charger. Setting a higher LVC prevents the battery from over-discharging even after self-discharge and improves the battery’s life.

Provides you with additional backup

A higher cutoff voltage allows you to get additional power in an emergency. Our premium range UPS comes with the option to set the cutoff voltage at either 10.5V or 11V. If you set it at 11V, it will create a power reserve in your battery. This reserve is similar to the reserve tank you have in your cars and bikes. In emergencies like those times when you have to keep your PC on for sending an urgent email, you can set the cutoff at 10.5V and get some additional hours of backup without the risk of deep discharge.  Keeping the low voltage cutoff at 11V increases your battery’s life by six to eight months.

It helps kick start the charging process

There is a common misconception among ordinary people that grid power starts the inverters. In reality, the inverter starts with the battery voltage only. If the self-discharge stage has drained all the juices in the battery, the inverter won’t start as the battery has used its reserve power too. Setting the LVC at a higher level ensures that when the grid power is restored, even after two or three days, your battery still has some juice to start the inverter and its charging process

What causes your battery to over-discharge?

Our mistakes often cause the battery to reach the deep discharge level, costing us the battery and the UPS/inverter. Here is a common battery-related mistake that causes the battery to over-discharge.

The inverter turns off when the battery voltage reaches a pre-determined low level. But it is too common for the users to restart the inverter/UPS multiple times to extract any power remaining in the battery. Meanwhile, the battery over discharges to dangerous levels.

Also, you might reduce the load to keep the battery running with the bare minimum load. For instance, if your battery has been powering two fans and multiple lights at its full charge, after restarting the inverter, you might reduce the load to a small 10-watt light bulb or a fan only.

At this stage, this load is running while the inverter is already signaling a low battery.  This small mistake reduces your battery and inverter’s life manifold. Therefore, it is strictly prohibited to drain the battery reserves and use the battery once the inverter signals a low-battery mark.

Conclusion 

Like overcharging, over-discharging is detrimental to the health of the battery too. Over-discharging reduces the battery’s life and affects the charging ability of your inverter. Adding an over-discharge protection feature to the inverter by setting a higher LVC (Low voltage cutoff) prevents the battery from going into the deep discharge state and overworking itself. A higher LVC is beneficial for the battery. The higher the LVC, the longer the life of the battery.