Do Car Batteries Need Water: Introduction, Effect and Symptoms

Jul 21, 2021   Pageview:30

The automotive battery is a necessary part of our vehicle. Without the battery, our car will not start. We must look after the automobile battery since it is the heart of the vehicle. We require every detail, even the amount of water required by the vehicle battery. 

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Battery watering is critical for extending the battery life of your forklift. Preventing premature battery failure and costly battery replacement is made easier with proper watering. Seeing the importance of water batteries, today we've decided to discuss car battery water.

Do car batteries need water refills?

Water plays a crucial role in a car battery's electrochemical equation. Although most vehicle batteries are sealed and do not require maintenance, they do have a water level indicator that allows you to check if there is enough water in the battery.

Low water levels lead the electrolyte to become unbalanced, causing the battery cells to become too acidic and the battery plates to sulphate. Non-conductive lead sulphate crystals will also prevent current from flowing through the electrolyte.

What happens if battery water is low?

Water is present in all lead-acid batteries, and the amount of water in them may decrease with time. Furthermore, a lack of water decreases the battery's power and may shorten its longevity over time. Overall, a battery that is devoid of water has a lower chance of surviving. The problem is tolerable if the water level is low, but it has a considerable impact on performance. When a battery runs out of water, it starts to self-discharge, causing it to age prematurely and perhaps stop working.

There are a number of reasons why the battery loses water, however the one listed below is the most prevalent.

When a car battery is overcharged, water is commonly lost. This can happen if you use a car battery charger that doesn't include a float mode or a built-in ambient temperature sensor.

The amount of heat a battery is subjected to affects its capacity. Colder temperatures diminish battery capacity, whereas warmer temperatures increase it. When a battery is overcharged, it heats up, enabling more current to flow into the battery.

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If the charger does not account for ambient temperature, an overcharge voltage may result, allowing an excessive amount of current to flow into a fully charged battery. Excessive current promotes water breakdown in the electrolyte, causing the vehicle battery to age quickly.

Furthermore, excessive overcharging can cause thermal runaway, which occurs when the battery continues to heat up and capacity rises, allowing the charger to deliver more current into the battery. A lead-acid vehicle battery might be killed in a couple of hours if this happens.

It is important to check the water level on a regular basis to guarantee that your battery lasts as long as possible. To avoid overcharging, make sure your automobile battery charger has a float mode and an ambient temperature control sensor.

Battery Low on Water Symptoms

The most common signs of low water on vehicle batteries are the ones that occur most frequently. Other electrical concerns include slow or no cranking, fading lights, alternator or battery light blinking on, and other electrical problems. Even the bleeping of the Check Engine Light might indicate a problem with the battery.

Most automobile batteries have caps that can be removed (popping them off may need a flat screwdriver) so you may replenish them with distilled water if necessary. Water is rarely, if ever, required by car batteries, commonly known as SLI (starting, lighting, ignition) batteries.

You should know how to check if the water in your vehicle battery is low in order to get the most out of it. On the top of the battery, there is usually a transparent “eye” that displays a green light if the water level is good and a black light if the battery needs water.

Before checking the battery, you need to make sure to clean any dirt or debris from the top of the battery and around the battery connections before checking the water levels. This is crucial because when you open the battery cells, you don't want any foreign material to go inside them. A clean battery surface also aids in the slowing or halting of corrosion on adjacent metal.

If you want to change the water, be sure it's pure. Impurities in tap water, such as minerals, accumulate on the plates of the battery's cells, decreasing the battery's capacity and useful life. Filling vehicle batteries with clean water, such as deionized or distilled water, is recommended by professional auto technicians and car battery manufacturers.


You may purchase equipment to test the quality of your water. It is advised that you use deionized water if your water includes more than 100 parts per million of non-dissolvable material. Minerals and pollutants in city and well water should not be in the battery since they might harm it and cause water system malfunctions.

Moreover, the valves do not work correctly if the water pressure is not adequate and a single point watering system is utilized, resulting in over or under filled cells.

For those who would like to change the water, , here is how you do it:

1. Turn off the car's engine. Locate the battery under the hood of the automobile. The battery's vent covers should be removed. To avoid getting dirt and debris into the automobile battery, clean the top of the battery before opening the inspection covers.

2. Check the water level in each battery cell. When refueling a car battery, only use pure water. Using anything other than pure water will result in your battery's irreversible failure.

3. Fill the batteries with water until it reaches just below the bottom of the cell inspection hole. Make sure the water level isn't too high. The acid water mixture may leak as a result of this. Fresh water should be used to flush any acid water combination that has spilled. Replace the vent caps on the battery.


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