The electrolyte is a solution of approximately 37 % sulphuric acid mixed with 63% pure water.

It has a specific gravity of 1.280 g/cm3 at 27o C when the battery is fully charged.

The electrolyte is the current conductor between the positive and negative plates and is a common reagent in the mass transfer process necessary for the reaction which takes place to convert electrochemical energy into electrical energy.

The PROBE MF PREMIUM battery contains enough electrolyte to last the normal life of the battery. The PROBE Maintenance Free sealed feature eliminates typical problems of improper servicing like overwatering, spillages and contaminations.

Flooded batteries have the built-in hydrometer feature or require the use of the bulb hydrometer to check the state-of-charge of the battery.

AGM (Absorbed Glass Matt) and Gelled electrolyte batteries can only be checked by way of the open circuit voltage method to determine the state-of-charge.