Last updated on January 12th, 2019 at 09:57 am
An alternative to using a battery hydrometer and a more accurate and safer way of measuring the specific gravity of battery electrolyte is using a battery refractometer. Unlike the former that uses the principle of buoyancy to determine the specific gravity of fluids, the refractometer works by utilizing the refractive properties of liquids. Generally, refraction is the property of bending light. Liquids that are denser than water (possess higher specific gravity) tend to bend light through a prism more than less dense fluids.
In this article, we shall review the five best battery refractometer instruments that can be used to measure battery specific gravity. As a bonus, these instruments can also be used to determine the freezing point of ethylene-glycol and propylene-glycol based antifreeze or coolant fluids. If you are an auto mechanic or work in the automotive industry, you definitely understand why it is important to measure the freezing point of engine coolant especially after mixing it with water. A properly mixed coolant remains in liquid form even in very cold weather such as during the winter. As a result, the engine remains protected throughout the extreme weather conditions without the risk of the coolant solidifying and causing damage to the engine. A refractometer helps get the right water-coolant ratio.
Best Coolant and Battery Refractometer Units Comparison Table
Detailed Review of Battery and Coolant Refractometer Instruments
Aichose 3-in-1 Battery Acid and Coolant Refractometer Review
The Aichose 3-in-1 refractometer is a high precision optical instrument used to test antifreeze coolants and battery electrolyte. It comes in a nice hard plastic case with tools to clean and adjust if necessary. Among the three parameters it measures are 2 properties of ethylene glycol or propylene glycol based automobile antifreeze coolants and the specific gravity of battery acid hence the term 3-in-1.
The instrument features high quality optics with ultra smooth focusing including an optical lens that has a high refractive index for high precision. All these are protected under a durable aluminum alloy body. You see three scales when viewing through the viewfinder; the specific gravity scale, temperature scales for ethylene glycol fluids and propylene glycol fluids, and concentration scale. The temperature scales are in Fahrenheits, concentration scale in percentage, and the specific gravity scale is unitless and ranges from 1100 to 1400.
Battery acid is very corrosive. However, the materials used to build the aichose refractometer are resistant and therefore do not corrode with acidic or alkaline solutions. This makes the instrument a perfect choice for using to check the strength of battery electrolyte and for measuring glycol levels even in hydronics heating systems. Storage of this instrument is nothing to worry about because it has a compact sturdy plastic casing that protects it from impact.
In a nutshell, Aichose 3-in-1 refractometer is a very useful, easy-to-use optical instrument that performs three important functions that help keep your car engine and flooded battery in good condition. You can use it to measure the specific gravity of battery acid, the freezing point of antifreeze ethylene glycol and propylene glycol coolants, and the concentration of those coolants.
Agriculture Solutions Antifreeze Refractometer Review
This is another optical refractometer for glycol, antifreeze, coolant, and battery acid. It has a solid construction and comes packed together with other accessories in a hard plastic carrying case. The instrument is equally easy to use and has easily readable scales for making accurate readings. In addition, the tool has a smooth focus adjustment to enhance viewing.
The Agriculture Solutions Antifreeze Refractometer measures three different types of liquids. It measures the freezing point of automobile antifreeze based on ethylene glycol or propylene glycol as well as the specific gravity of battery electrolyte in flooded batteries. In addition, this optical instrument also measures fluids based on ethanol or isopropyl alcohol such as the screenwash antifreeze.
Similar to the Aichose refractometer, this unit also displays temperature in ° C and has a range of -50° C to 0° C. In addition, it also has an automatic temperature compensation for low temperatures between 0° C and 30° C. Through the viewfinder, you three different scales. One of the scales is for specific gravity that ranges from 1100 to 1300. The second scale is for measuring the freezing point of automotive coolant. It has two sides; one for ethylene glycol based coolants and the other for propylene glycol based fluids. The scale spans from -50° C to 0° C and have a resolution of 1° Celcius for increased precision. The third scale is for measuring the freezing point of screenwash antifreeze. Again it has two scales side-by-side; one side measures isopropyl based fluid while the other measure ethanol based solutions. The screenwash scales range from -40° C to 0° C and have a resolution of 5° Celcius.
Generally, the Agriculture Solutions refractometer is a great, well built optical instrument to have for measuring automotive coolants and battery acid. It also adds the measurement of windshiled fluid as a bonus function. Most of all, is affordable and comes packaged with other accessories in a nice hardy carrying case that makes it easy to pack with the rest of the tools.
Hamh Optics&Tools 4-in-1 Hand Held Refractometer Review
This instrument as well has a solid sturdy construction with an aluminum alloy body for imcreased durability. Its optical components including the prism are made of materials that are resistant to abrasion and corrossion to allow them work with acid and alkaline solutions. This measurement tool features a focus adjustment and a rubber grip just like the rest of the refractometers reviewed thus far. In order to ensure that the readings are not affected by temperature variations, this optical instrument features an automatic temperature compensation for temperatures between 32 degree F to -60 degree F
The Hamh Optics&Tools 4-in-1 portable refractometer combines functions: 1) checks the health of battery electrolyte, 2) determines the freezing point of ethylene and propylene glycol automotive coolants, 3) measures the freezing point of windshield washer fluids, and 4)determines the concentration of urea in AdBlue (a solution of water and urea used to lower emissions in diesel powered engines). The scales for measuring the freezing point of engine coolants are in Fahrenheits and range from -60° F to 20° F with a resolution of 5° F while that of screenwash fluid ranges from -40° F to 15° F. The scale for AdBlue, on the other hand, is in percentage and ranges from 30% to 35% with a resolution of 0.19%.
If you are looking for a portable optical tool that will not only measure the freezing point of antifreeze liquids and sniff out bad batteries, the Hamh Optics & Tools 4-in-1 battery refractometer is a great choice. It will also measure the concentration of AdBlue to ensure that you get the right concentration which will break down harmful exhaust gases from your diesel-powered engine. In addition, this tool will also measure the freezing point of screenwash fluid. The only downside is its less robust plastic carrying case that may not effective protect the instrument from impact. Other than that, the tool is affordable and great to have in place of a hydrometer.
Extech RF41 Portable coolant and Battery Refractometer Review
The Extech RF41 portable battery acid and coolant refractometer is a high precision optical instrument from Extech company. It measures the freezing point of automotive coolants and the specific gravity battery electrolyte. It is easy to operate and has an quick to read scale for specific gravity readings and the freezing point temperature in degrees celcius. It also comes packed nicely in a solid plastic carrying case that stows away nicely in a tool box.
Like the Agricultural Solutions refractometer, this optical instrument is also built with high quality and non-corrosive optics and requires only 2-3 drops of sample for fast and accurate readings. It also features an automatic temperature compensation from 10° C to 30° C to ensure that the readings are as accurate as possible. However, it only has 2 scales; the specific gravity scale ranging from 1150 to 1300, and the temperature scale for ethylene glycol/propylene glycol ranging from -50°C to 0°C.
Extech RF41 refractometer is a high performance optical instrument from Extech company. It works well for measuring the freezing point of automotive coolants, glycol in chiller systems, hydronic and free cooling systems among others. The exceptions, however, are that the instrument does not measure concentration percentage of glycol, its automatic temperature correction does not cover lower temperature, and that the instrument is quite expensive.
Ade Advanced Battery and Antifreeze Refractometer Review
Ade advanced optics refractometer is a portable precision instrument for measuring the freezing point of ethylene or propylene glycol based coolants. It is very similar to the other competitors as far as the compact aluminum alloy body construction is concerned. It is also made of high quality optics with smooth focusing for accurate measurements. In addition, the components are resistant to corrossion allowing it to perfectly work with acidic and alkaline solutions.
The hand refractometer is capable of measuring three different properties of fluids. In other words, it can be used to check the strength of battery elctrolyte, determine the freezing point of automotive coolants as well the concentration of ethylene or propylene glycol antifreeze in water by percentage. Like the other units, this refractometer has an automatic temperature compensation for temperatures between 32 degree F to -60 degree F therefore allowing you to make accurate measurements.
Ade Advanced Refractometer is a great tool for in-depth analysis of lead acid batteries. It is good for testing golf cart batteries and flooded batteries of your offgrid system because it provides more accurate specific gravity readings than a hydrometer and is quick to read. It also measures the freezing point of engine coolants and displays the temperature in Fahrenheits. In addition, this tool can be very handy in determining the concentration in percentage of ethylene/propylene glycol based solutions. The downside, however, is the cloth carrying case that does not protect the fairly delicate tool from impact.
How to Use Battery Refractometer
- Battery acid and other machine fluids can be really dangerous. You have to remember to put safety first. At a minimum, put on safety goggles, rubber gloves, and closed work shoes.
- Ensure the Refractometer is clean before using it. Otherwise, rinse it using RODI water and wipe it.
- Suck the sample (battery electrolyte, engine coolant, AdBlue, or windshield fluid).
- Place a few drops of sample on the prism lens or view area.
- Allow it to cool briefly.
- Put the cover plate back in place carefully.
- Look through the view finder. You will see a line marking the split between a white and blue area.
- If you are having a hard time seeing the markings clearly, turn the focusing ring on the eye piece until it clears up.
- Read the respective scale depending on the type of sample. For battery acid, use the specific gravity scale, and for automotive coolant, use the antifreeze scale. Do the same for AdBlue and Screenwash fluid.
- Be sure to check each cell and record readings if you are testing a flooded battery.
- Again, for battery electrolyte, use the battery manufacturer’s chart that makes the correlation between specific gravity and percentage of charge to determine the percentage of charge of battery.
- Rinse the refractometer using distilled water and wipe using the soft cleaning cloth.
- Store the instrument back nicely in its carrying case together with the accessories
Requirements: You need a pipette, soft cleaning cloth, and RODI water for rinsing the equipment.
How to Calibrate a Refractometer for Machine Coolants and Battery Acid
- Open the cover plate and check the prism for any finger prints, dust, dirt, or debris
- Wipe the view area clean.
- Rinse the refractometer with RODI water.
- Remove the rubber cover of the calibration adjustment screw.
- Add refractometer calibration fluid on the prism evenly and place the cover.
- Let the refractometer sit for about a minute to allow the calibration solution to adjust to the temperature of the refractometer.
- Find a bright source of light to help read the measurement lines more clearly.
In order to properly calibrate a portable handheld refractometer, you need at a minimum the following five items:
1) RODI water
2) 35 part calibration solution
3) Flat head screwdriver
4) Soft cleaning cloth
5) User manual
Once you have all those in place, use the following procedure to successfully calibrate a refractometer.
Maintenance Tips for a Battery/Antifreeze Refractometer
A portable handheld refractometer is a fairly delicate optical instrument that requires care and regular maintenance to keep working optimally and effectively. The following are some of the care and maintenance tips for a battery and antifreeze refractometer.
- Protect the glass prism from scratches
- Proper storage
- Rinse and clean
Scratches and chips can greatly affect how light enters the refractometer and ultimately affect the accuracy of measurements. It is therefore important to protect the optical instrument from damage to ensure that you are always getting the most accurate readings possible.
Always make sure you store the tool back into its protective case after use because slight drops and bumps can dislodge or move the refractive mirrors inside.
It is good practice to always rinse and clean your refractometer after use to ensure that your readings are always correct. This also makes the tool always ready for use every time you want to use it thus saving time.
Frequently Asked Questions (FAQ)
- What is a refractometer?
- What does a refractometer measure?
- How to read a refractometer
- What is the difference between a battery hydrometer and a battery refractometer?
A refractometer is an optical instrument that uses the concept of bending of light by fluids to determine various properties such as freezing point, concentration, or specific gravity of a sample fluid.
A refractometer in the automotive industry can measure the freezing point, concentration, and specific gravity of different types of industrial fluids. For example, you can use it in place of a battery hydrometer to measure the strength of battery acid. You can also use it to measure the freezing point or concentration of ethylene or propylene glycol based antifreeze coolants such as Dexcool. Some even measure the concentration of AdBlue fluids and the freezing point of windshield fluids. Keeping the vehicle fluids from freezing protects your car during arctic climate such as in the winters. Fpr instance, frozen coolant in the cooling system of your car can severely damage the engine.
To read a refractometer, you place your eye on the eyepiece and through the viewfinder, you will see a line marking a split between a white and blue area. You then read the desired measurement from the respective scale. However, if the scale is not clear enough, you can increase the illumination on the prism and turn the adjustment ring to achieve a fine focus.
The main difference lies in the principle upon which both units operate. While battery hydrometers rely on the principle of buoyancy, a refractometer uses the property of refraction or rather the bending of light when it passes through fluids. Another difference is the amount of sample needed for each tool. A refractometer only needs 2 to 3 drops of sample whereas a hydrometer needs enough sample to carry the float.