An alternative and the most accurate way for measuring the specific gravity of battery electrolyte is using a battery refractometer. Unlike a battery hydrometer 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 review some of the best battery refractometer instruments that measure the specific gravity of battery acid and as a bonus, 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 after mixing it with water. A properly mixed coolant ensures that it remains in liquid form even in very cold weather like during the winter. As a result, the engine remains protected without the risk of the coolant solidifying throughout the extreme weather conditions.
5 Best Battery Electrolyte and Coolant Refractometers Review
Extech RF41 Portable Battery Coolant/Glycol Refractometer with Automatic Temperature Compensation (°C)
Antifreeze Refractometer for Glycol, Antifreeze, Coolant and Battery Acid.