Battery Specific Gravity-Calculation, Checking, And Usage

Are you hunting for some reliable and accurate information relating to battery-specific gravity? Well, if yes, then you have landed on the right website because, in this article, we will let you know everything about battery-specific gravity. Many of you might already be aware of what battery-specific gravity is, but if you are the one who is unaware of it, then there is no need to worry because we are here to help you out!?

Specific gravity is defined as the ratio that compares the weight of any liquid to the weight of an equal volume of water. The specific gravity of pure water is 1.00o. The lead-acid batteries use an electrolyte that contains sulfuric acid. Since the electrolyte of a lead-acid battery has a mixture of sulfuric acid and water, the specific gravity of the electrolyte will thus fall between 1.000 and 1.835.

This was just a brief description of what battery-specific gravity is! Now, let's start with the article and get a detailed understanding of calculation, checking, and usage of battery-specific gravity.

How Do You Calculate Specific Gravity Of A Battery?

?Whenever it comes to battery-specific gravity, the first and foremost question that might strike in your mind is- How to Calculate the Specific Gravity of a Battery? Well, we have got an appropriate answer to this question but before answering, let's get an insight into "What Is Battery Specific Gravity"?

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The lead-acid batteries that are used in automobiles are made up of lead, lead oxide, plates in a solution of an electrolyte. This electrolyte solution contains 65% water, and the rest 35% is sulfuric acid. The weight or the specific gravity of this solution increases as the battery charges, and alternatively, it starts decreasing as the battery discharges. When the battery gets discharged, the sulfur moves away from the solution towards the plates, and when the battery is charged, the sulfur returns back to the electrolyte solution. Therefore the specific gravity of the electrolyte entirely depends upon the 65% to 35% ratio for the required chemical reaction to take place. The ratio of 65% to 35% is highly affected by the temperature of the solution and the amount of sulfuric acid.

Now, to calculate the specific gravity of a battery, you will need a Hydrometer. A hydrometer is a device used to measure the specific gravity of the electrolyte solution in each battery cell. It is a commonly used tool that is used to measure the weight or density of a liquid compared to the density of an equal amount of water. Speaking about lead-acid batteries, a lead-acid battery cell is fully charged with a specific gravity of 1.265 at 80 °F.?

So, by using a hydrometer, you can easily calculate the specific gravity of a battery. Now let's move forward and look at when you should check the specific gravity of a battery!

When Should You Check Specific Gravity Of A Battery?

?The specific gravity must always be checked whenever you want to test the state of charge of a battery cell. Specific gravity is one of the most direct and accurate ways to determine the state of charge of a battery. Testing the specific gravity of a battery can be pretty challenging and time-consuming on the first go. You must always keep safety measures in mind while doing the specific gravity test.

The states of charge of a battery at multiple specific gravity at 77°F are as follows:

?100 % charged at specific gravity between 1.255 to 1.275

?75 % charged at specific gravity between 1.215 to 1.235

?50 % charged at specific gravity between 1.180 to 1.200

?25 % charged at specific gravity between 1.155 to 1.165

?0 % charged at specific gravity between 1.110 to 1.130

What Is Used To Check Specific Gravity Of A Battery?

As stated above, a hydrometer is a device used to check the specific gravity of a battery. The specific gravity of a battery checks the state of charge of a battery. In other words, it is essentially the ratio of the weight of a solution to the weight of an equal amount of water. As hydrometers do the testing of the battery's specific gravity, it is crucial for you to know that the best of these compensates for the temperature automatically.

The ratio of water to the sulfuric acid inside the battery changes with activity, and hence the density of the electrolyte also changes. This is where the hydrometer comes into the picture because this is what the hydrometer measures. In order to test the specific gravity of a battery with a hydrometer, you must follow the below-mentioned steps. Have a look!

?Specific Gravity Test For Flooded Batteries

Before starting this test, make sure not to add water at this time.

?Squeeze the bulb of the hydrometer.

?Insert the flexible tube of hydrometer into the electrolyte, which is present in the hole of a battery.

?Release the bulb of the hydrometer slowly. By doing this, the electrolyte will enter into the clear cylinder of the hydrometer.

?The float inside the clear cylinder will have risen some.

?Orient the hydrometer so that it is vertical and the float inside is floating without touching the insides of the clear cylinder. In this step, the top of the electrolyte must be in the green, white or red area of the float. If the top of the electrolyte is not floating in any of these areas, then make sure to get some more or less electrolyte as needed.

?Observe the color on the float that is lined up with the top of the electrolyte. You can even read the adjacent numeric value if given for the specific gravity.

?Finally, squeeze the bulb of the hydrometer in order to put the electrolyte back in the cell of the battery.

This is how you can easily use a hydrometer to measure and calculate the specific gravity of the battery. Always remember that the higher the acid concentration in the electrolyte, the higher will be the specific gravity of the battery.

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The Final Verdict

This was all about "Battery Specific Gravity: Calculation, Checking, And Usage"! We hope that all your queries relating to the battery-specific gravity have now been cleared in an accurate and precise manner. So, whenever you want to measure the state of charge of a battery, keep a hydrometer ready and measure the specific gravity of a battery. The steps mentioned above will surely help you calculate or measure the battery's specific gravity flawlessly.