5 Symptoms Of Low Water In Car Battery. How To Refill?


Despite the prevalence of maintenance-free car batteries on the market, many people still use more conventional wet batteries. In simple terms, these are batteries that you have to maintain by topping them up with battery water. But how do you know when that water runs low?

Low water levels in a car battery will manifest in different ways. Firstly, you’ll notice warning lights on your dashboard, like the battery, alternator, or check engine lights. Then, your car will crank slower than usual, and its electrical accessories won’t work correctly. Finally, you’ll also find the battery loses capacity and corrodes faster than usual.

This article will first explain to you why your car battery loses water. Then, you’ll understand why it’s crucial to recognize the 5 symptoms of low water levels and how you can refill the battery yourself.

Why Do Car Batteries Lose Water?

Your car battery contains a mixture of battery acid and water inside. That mixture is necessary to facilitate the chemical reactions inside that help the battery hold a charge, discharge electricity, and recharge continuously.

Those chemical reactions generate heat which raises the water’s temperature and causes it to evaporate gradually. That’s why you’ll find that the battery water level is low, and you need to top it up with new water.

More specifically, you must use deionized or distilled water to do so. Tap water and any other kind will not provide the battery with the electrical conductivity it needs to function. 

On top of that, the contents of tap water also cause long-term internal damage to the battery.

That’s how batteries lose water under normal working conditions. Besides that, batteries also lose water when the vehicle is in extremely cold climates. The low temperatures cause the water and acid in the battery to separate, with some of it leaking out.

Furthermore, overcharged car batteries or those that suffer damage can also leak water through the battery casing.

Read: What Are The Signs Of An Overcharged Car Battery?

What Are The Symptoms Of Low Water In A Car Battery?

Unfortunately, you can’t always tell that your battery is running low on water. That’s because the battery is located under the hood of your car, and there are no water level indicators on your dashboard.

Thankfully, there are signs and symptoms that you can look out for.

Here are 5 symptoms of low water in a car battery:

1. Warning Lights

The first hint that your car battery water is running low is when you see warning lights on your dashboard. 

As you read earlier, you won’t find any gauges measuring the water levels inside your battery. However, when water levels run low, and the electrical system experiences problems, one or more of the following warning lights will turn on:

  • The Check Engine light
  • The battery warning light
  • The alternator warning light
  • Other indicators unique to your car brand and model

These warning lights can be triggered by many different issues, not just low battery water levels. However, their purpose is to prompt you to check under the hood for a problem.

You must consider the low battery water level as a possible cause when that happens.

Read: 3 Signs That Your Car Needs a New Battery

2. Weak Or Faulty Electrical Components

Another soft hint that your battery water levels are low is when your car’s electrical components are weak or faulty.

A battery without enough water will suffer problems and disrupt your car’s electrical system as a whole.

So, for example, you might experience problems disabling your car’s central locking remotely. Alternatively, you might see your car lights (inside and outside) flicker and remain dim.

The battery is the heart of your car’s electrical system, so check its water levels first to ensure it has what it needs to function.

Read: Does a Car Battery Charge When Idling?

3. Slow Cranking

You can often gauge the health of your car’s battery by what happens when you start the engine. A healthy battery with enough water will have no problems cranking within a short time frame of 1-2 seconds.

However, slow cranking hints that your battery might lack enough water.

Remember: low water in a car battery disrupts its ability to store, recharge, and discharge electrical power. When it can’t discharge enough cranking power, your car will take several seconds longer to start the engine.

Read: Why Car Won’t Start With New Battery?

4. Reduced Battery Capacity

So far, you’ve seen that low water levels in a car battery prevent discharging electricity correctly (e.g. to power electrical accessories and crank the engine).

Now, let’s look closely at another crucial battery function: storing electrical power. The battery’s ability to do so, also known as its ‘capacity’, will be significantly reduced when there’s insufficient water inside.

You can confirm this by measuring the battery capacity with a multimeter. Alternatively, if you regularly use the car battery to power external devices, you can take note of how long it lasts before going flat.

When a car battery dies faster than expected, it’s a sign that it has lost its capacity. That likely happens because its water levels are low.

Read: Why Car Battery Terminals Corrode?

5. Corrosion Buildup

Lastly, a close-up inspection of the battery will show it has a buildup of corrosion around its terminals. That occurs because low water levels expose internal battery components to air, causing them to rust faster than usual.

That rust or corrosion spreads quickly and becomes apparent outside the battery, particularly on the terminals.

How Do You Refill Water In A Car Battery?

You can refill the water in your car battery in 5 quick steps. 

Here’s how:

  • Step 1 – Inspect: Firstly, inspect the car battery and check for any damage signs. A damaged battery must be replaced, not refilled.
  • Step 2 – Check: Once you’re sure the battery is healthy, check the water levels to see how much you’ll have to pour in. The goal is to pour the correct amount, not too little or too much.
  • Step 3 – Open: Next, remove the battery caps to expose the openings where you’ll pour water.
  • Step 4 – Pour: Then, pour the correct amount of water inside the battery. Be sure to use only deionized or distilled water. Never use tap water or anything else.
  • Step 5 – Close: Lastly, check the indicator to confirm that you’ve poured the correct amount of water in. Then, twist the battery caps securely to keep the water inside the battery.

As a general rule of thumb, you should check your car battery’s water levels at least once every week. That way, you’ll never let the battery lose enough water that it starts to suffer any internal damage.

Plus, that weekly check allows you to catch battery problems when they’re still minor. For example, suppose you notice the water level dropping more often than usual. In that case, you’ll know that’s a sign of a more severe battery problem like a leak or physical damage.

Final Thoughts

Your car battery plays a crucial role in the vehicle’s electrical system. That’s especially true when cranking the engine, as a weak battery will immobilize your car. So, recognizing the symptoms of low water levels is crucial.

A battery with low water levels will cause slow cranking, weak electrical components, and warning lights to appear on your dashboard. Besides that, the battery will have a lower capacity and experience corrosion.

You can prevent these problems by checking the water levels weekly and pouring only deionized or distilled water through the openings when necessary.

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