Water In The Car Battery – The Definitive Guide

by Phil Borges // in Car

Have you ever wondered if car batteries have water? Do you know why the car battery needs water? How much water should be in your car battery? The answers to these questions may not be as simple as you might think.

No need to worry because, in this post, we will discuss some frequently asked questions about everything related to a car battery’s water and its suggested levels so that you will have an understanding of what it means for your vehicle.

What is the role of water in the car battery?

The car battery is like a small power plant powered by water, but it needs to have the correct voltage level. Although many batteries are sealed and maintenance-free, they often include an indicator for you to check if there’s enough water supply in them or not.

When it comes to a car battery, water is the ultimate power source as it plays an integral part in electrochemical reactions.

Batteries work when the water level is correct. If the water level is too low, the battery becomes too acidic, and it can’t conduct electricity that can lead to a dead battery.

What is the first sign that the car battery needs water?

Batteries that are left without water for too long will become corroded and can’t provide enough electrolytes to help the current flow, which could be hazardous to your vehicle’s engine. But how do you know when your car battery needs water? Corrosion can happen when the battery is not used for a very long time.

Corrosion on the terminals is a severe problem for vehicles. It can happen when different metals are touching each other and electrolysis occurs, or from an imperfect seal between terminal posts and plastic casing that lets in sulfuric acid with lead to corrode them.

Many people fear corrosion but don’t think twice about touching or inhaling toxic lead sulfate because it can cause serious occupational hazards.

To avoid corrosion, you need to take precautions like using terminal protectors to allow metal surfaces in contact with each other without any chance for corrosion.

Why does a car battery lose water?

Overcharging a car battery is mainly the reason why the water level is diminishing. If this happens often, then there will be no enough fluid left inside, and completely dry cells are incapable of generating any power at all. This will prematurely age the battery faster than you would want to.

Do car batteries discharge if not in use?

Batteries used in vehicles are under constant pressure to keep the engine running. This means that your car battery will discharge over time, even if it is not being accessed for use.

If your car battery is connected to the engine, don’t forget that there are many reasons it could drain in addition to just being used by the engine. All accessories and computers will also drain out power from your battery when you’re not running on gas or diesel fuel.

Batteries have a finite life cycle. The manufacturer and decreases set the lifespan as you use it more often, charge too high or low, leave your lights on when not in use for extended periods of time. However, there are some things that we do to make our batteries last longer, such as take care of how deep we discharge them before charging them back up again.

Can I add water to the car battery myself?

Some people may not know that they are supposed to refill their batteries every once in a while too.

To do so, make sure there’s enough space for some liquid and then pull down on one of its caps using a flat screwdriver until the seal pops open and allow just enough room at the top edge for pouring some fresh distilled water inside.

Distilled water is a must to optimize the battery’s life span. Tap water can create problems to the battery that could damage or even be ruined by its minerals.

How much water does a car battery need?

The amount of water needed for a battery is different from one to another, but generally, a car can use as much as 150mL on average.

To avoid corrosion and optimize life span, it’s recommended that you maintain the proper level of liquid inside your battery at all times by checking its indicator regularly and topping up when necessary.

What is a parasitic draw in a car battery?

Parasitic draw is one of the most complex forms of battery damage, but improper diagnosis can lead to a very costly mistake. If you have been using your car regularly and it has started acting strangely (i.e., gone dead overnight or after only two days), then there’s probably a parasitic draw.

Parasitic draw happens when something in your car draws power from the battery while you are not using it.

To test a parasitic draw, remove all the items that could be drawing power from the battery. Now, if your car starts behaving normally again without any problems, then you have found a parasitic draw and should take it to an expert for further inspection.

How can I extend the life of my car battery?

The average life span of a car battery is around four years. If you want to extend that life span, follow these few helpful tips:

– Keep the battery cool (below 80 degrees Fahrenheit).

– Don’t expose it to extreme temperatures on a regular basis.

– Avoid overcharging and deep discharges of your car battery.

– Make sure the terminals are clean and tight.

– Check your battery regularly.

– Keep the top of it dry, as this will help preserve any power left inside it.

– Always use distilled water in a car battery rather than tap or even rainwater for optimal performance.

Replacing the car battery may solve the issue If your car battery keeps going dead or flat. But, if it is less than four years old, get the alternator tested and consider a parasitic draw test performed by an auto mechanic. There might be a chance that the problem is not with your battery at all but coming from elsewhere in your car.


To prolong the life of your car battery, it is crucial to regularly check the water level and be sure not to overfill it with anything but only a distilled water. Always make it a habit to keep an eye out for the car battery water level indicator, which is a helpful tool for keeping your vehicle in the best shape.

We hope that this article has helped you better understand how to take care of your car battery and the importance of water in it.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.