6 Symptoms Of Low Water in Car Battery Symptoms

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this...Read more

A car battery ignites the starter motor and runs the electronics, making it an important part of the system. As it works combined with the electrolytes inside the battery shell, when you have a low water level, it starts to malfunction.

The biggest symptoms of running on a low water level in the battery are reduced backup time and lower fluid level.

If you’re experiencing malfunctions from the battery while starting the car or running the electronics, check the water level. Do this before deciding to get a new battery.

In this guide, we’ll walk you through the low water in car battery symptoms and how to check the water level. We’ll also discuss how to refill the water, maintain the battery, and get it back on its feet.

Prepare to get your hands dirty.

What Does Water Do in A Battery?

The battery works with chemical reactions across lead plates within the battery. This reaction takes place with the sulfuric acid that is 38% concentrated as an ideal level that runs from one point (negative) to another (positive).

What Does Water Do In A Battery

When the battery charges, the concentration increases and heats up the inside. So, we fill out the rest of the battery with distilled water that works as both a coolant and balance worker in the battery.

Why Does Water Reduce?

As the chemical reaction goes on and heats up inside, the water vaporizes bit by bit. At some point, it vaporizes to a point where it goes too low.

Also, while recharging the battery, some water breaks down to a molecular level (H2O). This process electrolyzes the hydrogen at the cathode and the oxygen in the anode.

We need to add water to the battery from time to time for two reasons here:

  1. To keep the inside of the battery cool while the recharging takes place and heats up.
  2. To compensate for the loss of water that has occurred during the electrolyzation.

Well, while adding water, tap water can have catastrophic outcomes for the battery as it contains minerals. Therefore, you must add distilled water, also known as battery water.

Low Water in Car Battery Symptoms

Okay, now you know the importance of distilled water inside the battery, and why it reduces over time. But, how do you know if the water inside the battery is dried out or low enough for you to refill?

Low Water in Car Battery Symptoms

Here are the symptoms that tell you the water inside your car battery is low:

Slow Crank Ignition

The most common problem that you’ll face because of low water in a car battery is not being able to start the car. When you put the ignition on, if the car tends to start but doesn’t, most probably the battery has to do with it.

And the most common issue with the battery is the low water level, especially if you’ve been using the battery for more than 3 years. Here, you can open the battery caps and see the water level before doing anything else.

Slow Crank Ignition - Low Water In Car Battery Symptoms

Or, you can check the battery’s voltage output with a multimeter.

The multimeter should not give you a reading of less than 10V during the ignition. It should be more than that while showing around 13V in idle mode.

Lower Backup

As mentioned earlier, the battery works with a chemical reaction between the anode and cathode using sulfuric acid. And the water plays a big role in keeping things cool and the battery efficient.

When you have a low water level in the battery, the battery experiences thermal throttling which causes battery inefficiency. This will eventually lead the battery to give you a lower backup time compared to regular times.

Higher Temperature

The obvious byproduct of having a low water level in a car battery is a higher temperature level. As the water works as a coolant for the sulfuric acid reaction, if you have less water, it doesn’t cool things as efficiently.

In fact, the lower backup issue essentially starts with a temperature rise that later causes throttling. The ideal temperature level of an automotive battery should be around 26° to 27° Celsius. So, if you see a higher temperature, it might be a good time to do an inspection.

Corrosion on The Battery Posts

As the water level goes down, the car battery’s inside plates are also exposed to bare oxygen. Now, the obvious outcome of this is building rust and corrosion inside the battery on the plates.

You might also see excessive corrosion on the connector terminals of the battery that connect to the connection wires. If you end up with rust, you have a clear idea of the possibility of a lower water level in the battery.

Swelled Battery Pack

Part of the work of the water inside the battery is keeping the inside cool during a charging cycle. When you have a low water level inside the battery, it partly deteriorates the cooling process.

That will lead the battery to overheat, throttle, and even worse, swell if the water level is too low. Your battery should be nice and flat in its place, without any swelling or bumps. If it’s swollen, it either needs a replacement, or at least the fluid refill.

Reduced Fluid Level

Simply put, water isn’t the only liquid you have inside your battery. It’s a mixture of both water and sulfuric acid. Every once in a while, even if you don’t have the symptoms or do not have a dead battery, you need to check the fluid level.

Knowing the ideal fluid level of the water and acid mixture will help you keep it working nicely. The ideal level would be just parallel to the lid cap of the battery. You can see the fluid, but only slightly touching the plastic cap from below.

It will be down around  3/4″ below like this:

Reduced Fluid Level - Low Water In Car Battery Symptoms

Filling Battery with Distilled Water (Topping Up)

So, you have your battery with the water level down, and you want to top it up. Here, you must use distilled water because tap water has things like minerals, chlorine, and other things that can damage your battery.

Here’s how you add distilled water into your lead acid car battery:

Take the Battery Out

First, clear this up: you can do this while having the battery in or out of the engine bay. Taking it out of the bay is what you actually want to do because that helps you clean things up, and avoid corrosion down the line.

Unplug the negative terminal first, using a torque wrench. Don’t use a regular adjustable wrench, and use a torque wrench extender if necessary. Then, undo the bolt that holds the battery in place to take off the entire battery

Clean and Remove the Ports

Now it’s time to undo the refill ports, but you should take extra time to clean them first. If you don’t clean it, there could be particles from the engine or the outside world that go into the battery and damage it.

As for cleaning the terminal and connectors, use a roll of sandpaper, or you can get a dedicated terminal cleaner. Once everything is clean on the battery, you can now go ahead and pry the port covers off. Usually, there will be two lids, covering 6 ports.

Refill The Water Properly

Topping up the battery with distilled water is easy if you know how it’s done.

First, inspect all the ports and see which ones need a water refill. Then take a bottle of distilled water and pour it in using a water dropper. You can also use a battery hydrometer as your all-in-one tool for the job.

Just remember to stop right when you have the water level parallel to just the bottom end of the top cap.

Put Everything Together

Once you’re done refilling the battery water, you can now put everything together. Reverse the procedure. This will include putting the caps up top, placing the battery in its place, and reconnecting the terminals.

However, reconnect the positive terminal (with a “+” sign to it) and then connect the negative ( with a “-” sign to it). It’s the opposite of what you did while removing them in the first place. And, don’t tighten the bolts too tight, keep it just snug enough to stay firm.

Demonstration of how to add water:

Watering a Car Battery: Safety Measures

Here are the safety measures to always keep in mind while inspecting, cleaning, or changing the car battery fluid:

  • Wear glasses: You’re working with electrolytes and sulfuric acid which means that you’re in danger if splashes go into your eyes. So, wearing a pair of safety glasses will come in handy.
  • Wear full sleeve: The same rule applies for your hands, which are the closest to the acid. Your hands can come at risk in contact with acid splashes. You can wear full sleeve shirt so that the hand is protected.
  • Wear gloves: It’s okay if you’re not wearing a full sleeve shirt, but not wearing plastic gloves certainly isn’t. Apart from electrolyte or acid splashes, you also have corrosion and electricity to deal with. You don’t want to handle them barehanded.

You May Also Read: Can You Use Dielectric Grease on Battery Terminals?

Final words

Checking the car battery and topping up the water yourself is a fairly easy DIY job if you know the process.

Check if you have a fillable lead-acid battery in the first place. If it’s not sealed and has removable lead caps, you can add water.

Check the fluid level manually even if you have no symptoms to understand the water level down. Do this every few months, like 6 months or so.

Once you have your battery water refilled and reattached, you don’t necessarily have to take it off the bay every time you top it up.

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this site Batteryquery to help people purchase the right battery for their vehicles. The reason behind creating this site is to help my customers purchase the right car battery who often purchase the wrong one due to their lack of knowledge.

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