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Why Distilled Water is Used in Batteries and How to Fill?

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Batteries are the heart of an inverter battery. And for batteries, distilled water is like the blood that can impact its life and durability.

If you are wondering why? Then this article is for you.

Here, we have explored the reasons why distilled water is essential for inverter batteries.

Along with that, we have also provided clear information on how to top up battery with distilled water.

All You Need to Know About the Distilled Water

Not many of us are technically sound enough, knowing everything about distilled water, how it works, and how it plays a crucial role in the battery’s life. 

Here’s the detail explanation…

Every inverter battery, irrespective of the type, contains internal plates immersed in a pool of electrolytes (a mixture of water and acid) responsible for the working of the device. During the operation of the battery, the water (H2O) undergoes a chemical reaction and breaks down into hydrogen (H2) and oxygen (O2) gas.

Over time and as the water level drops, these gases evaporate, no longer covering the plates.

If you want to ensure the effective functioning and performance of the battery, it is a must to refill it with distilled water. Make sure you fill an adequate amount of water into the battery.

Do not overfill or underfill it, but do it to the specified level to avoid battery damage.

The electrolyte present in the conventional batteries contains a mixture of sulphuric acid and water. It is important to note that you only add water to the battery and never sulfuric acid. During operation, the batteries will consume only water and not sulfuric acid.

Let us proceed further with why, when, and how to use distilled water for inverter batteries.

Why Do We Use Distilled Water For Inverter Batteries?

Distilled water is purified water that does not contain any of the minerals that regular tap

water contains, like calcium, sodium, and magnesium. Let us say you are filling the battery with the normal water. Since it has concentrations of ions, these clog the electrodes by forming a layer on them.

Eventually, these ions obstruct the chemical reaction inside the battery, hindering the work. This further stops the battery from generating a current. Hence, use only distilled water free from impurities to ensure the smooth and seamless functioning of the inverter battery.

When Should You Add Distilled Water in The Inverter Battery?

In the above paragraph, we learned why distilled water is essential. The immediate question that arises is when to add it? Here is the answer. All batteries have water level indicators on the top that show the level from time to time.

Keep checking the indicators to see if the level dropped below the specified limit. If in case it did, top-up the battery with distilled water immediately to the required level. Be careful not to refill the water to the maximum or minimum level in the water but to the exact level.

It is advisable to keep checking the water levels in the battery regularly, i.e., at least once every two months.

How to Top-up Water in A Battery?

Now that you know when to refill the distilled water, you should also be aware of how to do it. Here are the steps to help you learn how to add the water quickly and easily:

Step 1

As the first step, inspect the indicators to see if the water is up to the specified limit or not. There are marks on the indicators that show the water level. While the red mark depicts a lower water level, the green mark indicates a higher water level. Check for these indications, even before you decide to top up.

Step 2

If you observe a red mark on the indicator, it is time to refill the battery with distilled water. Before you start the procedure, make sure you switch off the power.  

Step 3

Now that you turned off the power, remove the vent plugs by twisting them in the counter-clockwise direction. Once you remove it, place a funnel in the hole to top up the water.

Step 4

Keep adding the water slowly to the required threshold. Make sure that the battery is fully charged before you start refilling the chambers. 

Step 5

Once you finish adding water to all the compartments, replace the vent plugs by twisting them in the clockwise direction. 

Step 6

Before you switch on the inverter battery, clean the surface of the battery, the indicators, and vent plugs with a clean cloth. See to it that they are free from dust and dirt to ensure uninterrupted working. 

Step 7

This is the last step. After you finished adding distilled water to the battery, turn the battery power on.

Note: Make sure you are wearing rubber gloves and safety glasses when filling the distilled water in the battery.

This is how you can clean the battery:

  • Prepare a cleaning solution by adding baking soda to water. Use this solution to clean the terminals. (Ensure that this solution does not enter the battery.)

Can You Use RO water in The Battery?

Many people often have this question in their heads. Can I use RO water to fill the battery? We reiterate that you should only use distilled water to top up your inverter battery. Although RO water is pure and good for health, you cannot use it as an alternative to the distilled water.

Where to Buy Distilled Water for Inverter Batteries?

Are you wondering where to buy the distilled water for inverter batteries? Do not worry. Distilled water is not scarce that you have to search for it. You can get them in the places mentioned below: 

  • The most common place where you can purchase a bottle of distilled water is a petrol bunk or petrol filling station. Each bottle would cost you around Rs. 20 to Rs. 50 per litre, depending on the place you are buying from. Make sure that you purchase one from a reputed petrol pump to avoid adulteration. Also, ensure that the water in the bottle is clean and the bottle seal is closed.
  • You can also find them in the battery selling shops. The battery vendors who sell them have the distilled water at their shops, and you can buy one from them. 
  • The distilled water bottles are available at the car servicing stations, as well. They keep the water with them to refill the car batteries. 

Some Frequently Asked Questions

1. Despite distilled water can I use the RO purified water for battery top-up?

RO is free from impurities, unwanted salts and ions. So, you can use the RO purified water, just make sure to keep a tab on its PH level, hardness and TDS (less than 5PPM). Also, ensure the working efficiency of the battery is not compromised.

2. How much TDS level of water should be used for the battery?

It is recommended to use TDS below 5 PPM for filling up batteries with water.


Wrapping up, distilled water is essential for maintaining impeccable performance and a longer life span of the battery. I hope this article gave you ample information on why, when, and how to add water to your inverter battery.

Since you are now fully equipped with the knowledge, try doing the same with your batteries. Share your experiences in the comments section below and let us know if this article was, indeed, helpful to you. If you have any questions, you can post them below. We would happily answer all your queries.

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