Putting water into a battery can seem like a strange thing to do…
Especially as we are taught as kids never the mix water and electricity.
But the world is a strange place, and there is always an exception to the rule.
In fact, when it comes to lead-acid batteries used with inverters, water is an essential component of its operation.
Without using the correct water, an inverter battery will become damaged and unusable.
So it’s important to keep it topped up with the right water.
In this article, we’ll go through what water is used in inverter batteries, why it’s important, how often to ‘water your battery’.
Use Distilled Water in Inverter Battery
You should always use distilled water in your inverter battery. It is not just a recommendation but the best way to ensure a long healthy working life of your battery.
It can be tempting to just use tap water, after all, it’s just water, right? I urge you not to do this and spend the extra twenty bucks of distilled water. Here’s why.
Why Use Distilled Water in Inverter Battery?
The liquid used in a deep cycle battery is known as an electrolyte. This solution is made up of acid and water which floods the battery. This liquid surrounds the lead plates (electrodes) which store the energy. The electrolyte solution serves as a catalyst to make the battery conductive and help ions move between the electrode.
Distilled water is the purest form of water which is key to the chemistry of a battery. In simple terms, it has no other chemicals or minerals to interfere with things.
If you use tap water it is filled with other chemicals and minerals. This causes a number of problems. Firstly, it can lead to a build-up in residue on the battery – it’s similar to limescale build-up in your kettle! This decreases your battery performance over time. Adding to this, the minerals in the water can interrupt the movement of electricity and even start to short circuit your battery.
Distilled water removes all these problems as it is completely pure so won’t leave a residue or conduct electricity.
What is Distilled Water?
If you can remember your science class then you might remember distilling water at school!
Distilled water is water that has been boiled and condensed back to a liquid into a separate container. By doing this you colled the pure water particles and leave behind anything else in the liquid.
For example, if you distill seawater you would be left with one container of pure water and one container of salt!
Distilled water is brilliant for use in chemical reactions (like in a battery) because it does not have any minerals (like salt) to interfere with the reaction.
Can I Use Tap Water in a Battery?
If you’ve read this far you will now understand that you can’t use tap water in a battery. It is filled with too many impurities and chemicals that will damage your battery.
Putting a little tap water in your battery will not instantly break it, but over time it will cause irreparable damage and reduce its ability to store energy.
How Often to Add Water to Battery and How Much?
It is a good idea to check your battery water levels every two months. You only need to refill it once the liquid falls below the min mark on the gauge. Make sure the water level is always between the min/max marks. If this is the case, then you don’t need to refill or replace the water. If there is no gauge, you should just make sure that the metal contacts inside the battery cells are fully submerged.
Do I need to refill the acid?
No, you won’t need to refill the acid in an inverter battery, just the distilled water. This is because only the water gets depleted during usage. Using energy creates heat which slowly evaporates the water out of the battery. The acid does not evaporate.
How to Refill Inverter Battery with Water
It is usually a simple process to refill water in an inverter battery. They should be designed to make this maintenance easy. Here’s a step-by-step guide:
- Put on protective gloves and eyewear. Batteries contain dangerous acid which you don’t want to get on your skin or in your eyes!!
- On the top of the battery, you should see one or more caps that cover the battery cells. They will be marked ‘Danger’ notifications.
- Remove the covers and you should see the battery acid inside. This is where you will add the water.
- Carefully, fill each cell up using a battery filler until the metal contacts are fully submerged. You don’t want them exposed to air. Some batteries might have a min/max gauge to help you judge.
- Securely replace the caps over the battery cells making sure no liquid can escape.
Here’s a helpful video to guide you through the process:
Where to Buy Water for Batteries?
Distilled water for inverter batteries is very easy to find. You can get it at most automotive stores, garages, or even on Amazon.
- Distilled Water
- Laboratory Grade
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Prices pulled from the Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Final Words on Water in Inverter Battery
That’s everything you need to know about water in inverter batteries, we’ve even had a little science lesson.
The key thing to remember is – always use distilled water in an inverter battery.
Some people might tell you other things are ok, but in the long run it will cause damage to your energy supply.
Stick to distilled water in your inverter battery.
Looking for a new battery? Read my guide to the Best Battery for Inverter Use.
Hi, I’m Michael, the editor here at Watt A Lot.
After years of experience with off-grid power like solar panels, inverters, and batteries I decided I should share my hands-on knowledge with you. In my professional and personal life, I’ve needed to find electrical solutions for remote situations from owning a food truck, to running events at the top of mountains, to my converted campervan. So whether you’re looking for the best products or fixing an electrical problem, you can rest assured my advice comes from real hands-on experience.