Due to it low cost, hydrometers are often used to measure the specific gravity or the concentration of the sulfuric acid in a battery. The specific gravity measurement reflects the state of charge of a battery. In other words, the higher the charge level of a battery, the greater will be the specific gravity reading. Over time, all acid based batteries will experience a depletion in active material, which is normal. The more pronounced the depletion, the lower the specific gravity will be in a fully charged battery. As batteries age the capacity to hold a charge deteriorates. Therefore, an aged battery even after going through a process of desulfation, will still show a lower specific gravity than a new battery.
A more accurate diagnosis of your battery health In internal combustion vehicles, batteries are essentially used to crank an engine and once the engine is running, the alternator kicks in to charge the battery and to drive the electronics in the car. So instead of measuring a battery's specific gravity, it’s actually more relevant to measure the CCAs or cold cranking amps of the battery. After all, you don’t need to know the charge level of the battery but rather how well it will crank your vehicle.
Specific gravity is an inaccurate measurement of a battery's performance because it varies according to the battery's state of charge. It doesn't show how much more life span is left in the battery.
Specific gravity is actually a poor indicator of the battery’s performance as it changes depending of the state of charge of the battery, and it doesn’t actually tell you how much more lifespan you have left in your battery. In addition, the maximum specific gravity varies from battery to battery. For instance, certain batteries only have a maximum specific gravity of 1.255 to 1.260 while Maintenance-Free batteries can go up to 1.280.
What is CCA or cold cranking amps? Cold Cranking Amps is a rating used in the battery industry to define a battery’s ability to start an engine in cold temperatures. The rating is the number of amps a new, fully charged battery can deliver at 0° Fahrenheit for 30 seconds, while maintaining a voltage of at least 7.2 volts, for a 12 volt battery. The higher the CCA rating, the greater the starting power of the battery.
To accurately measure the health of car batteries, buy our digital battery analyzer or find out more about optimizing battery life span with our battery desulfators.