Car batteries need proper care for them to give you the reliable service your car needs.
Sometimes though, it can be difficult to know, particularly if you are using the flooded Lead Acid batteries when they need more distilled water.
Note: while we use water in this article, we are referring to distilled or deionized water.
So, in this article, I share:
- why flooded lead-acid batteries need to be topped up with water
- what type of water to use, common signs that your battery is low on water, and
- step-by-step instructions on how to add water to your battery for it to perform optimumly.
Note: This article only applies to Flooded Lead Acid Car batteries
When Car Battery runs out of Water – Common signs
Symptoms of a Car battery with Low Water
When your car battery is low or has run out of water, then you will observe low performance of your battery.
I have listed below what can happen and some of the effects you may observe.
This can be more noticeable with newer car batteries as you can expect top performance from them.
- The top of your battery’s case may be wet or dried electrolyte residue.
- Car filing to start. Your car may crank slowly before starting or fail to turn over completely. Each attempted start can also result in an even slower cranking.
- The battery capacity reduces – you may notice for example that you need to jump-start your car in the morning whereas in the past this was not needed or your car audio system while on battery drains it sooner.
- Shorter battery life. Your battery can die sooner than is specified by the manufacturer – If you continue using your battery with low water.
You may also be interested in: Why your Car’s Battery Voltage Drops Overnight?
Flooded Lead Acid Batteries – Why you Need to Regularly Top up with Distilled Water
The water or electrolyte level in your flooded lead-acid battery reduces as you charge and discharge your car battery.
This is because, during both the charging and discharging of your car battery, there is an underlying chemical process where the water portion of the electrolyte used is broken down and reduces in the process, giving off both hydrogen and oxygen.
If you do not top up with deionized water, your car battery will not hold as much charge and will not last as long.
You may also be interested in: How many Volts a Car Battery needs to Start?
Type of Water to Use in Car Batteries (+ Why)
You should only use distilled water or de-ionized water in your flooded battery.
This is pure water, free of impurities that can react and damage the battery plates shortening their lifespan.
Tap water and other types of water – rain contains contaminants that will damage your battery.
Only use bottled water that is distilled or de-ionized otherwise you will damage your battery.
Also, make sure to keep the battery water in its original OEM container. By keeping it in the original container, you are reducing the risk of contaminating this water.
This is because it is possible for the water to pick up impurities from the containers you use.
How Much Water to Add (should be) to Car Battery
You should only add just enough battery water until the water level lines up with the recommended water line on the battery.
If you add excess water, you run the risk of changing the concentration of the battery’s acid mixture and affecting its overall performance.
When to add to the battery water is important as well. Add deionized water to your battery when the water level is barely covering the plates inside the battery.
How to Add Water to your Car Battery
To add water to your car battery, open the vent caps and place them upside down (not on the side) so that the underside of the caps does not pick up any impurities that can contaminate the battery water.
For the best performance of your battery, you should only add deionized water if it is fully charged.
So, check the water (electrolyte) level in the batteries. If the battery plates are exposed and not covered with water then top up each cell with deionized water until they are just covered.
Then charge the battery until it is fully charged.
Finally, top up each cell with deionized water until the water level reaches the maximum water level. Do not exceed this line to prevent electrolyte from leaking through the caps as the battery is charged.
How Often to Add Water to a Car Battery
There is no one answer that fits all.
It really depends on how much the battery is used. If there is a lot of driving for example, then you will need to top up battery water more often compared to a car that is not driven as much.
Higher temperatures can also increase how often you need to top up your battery with water.
How much current is used during the charging process also affects how often you need to add water.
Faster charging rates require higher charging currents and batteries will require more frequent water top-ups compared to slower charging.
Lastly, the age of the battery is another factor. Older batteries tend to require more frequent water top-ups compared to newer batteries.
So, it is probably best to check your car battery’s water level at least monthly and top up as described above. Depending on the observations you make, you may need to increase how often you top up with water.
Final thoughts
Flooded lead-acid batteries need to be periodically topped up with distilled or deionized water to make up for what is lost during the charging and discharging process.
You should inspect and monitor your battery’s water level monthly but you may be able to tell that you are low on water when your battery loses its capacity to hold charge, drains quickly overnight, or cranks slowly.
Note that these are not confirmatory tests as it could as well be that your battery is about to fail because of age or defects.
Hope this helps! Feel free to leave a comment or question below.
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