There is no need to add water to the maintenance-free battery electrolyte.
Pic. 7.47. Air vent in the battery cover
The battery is completely sealed except for a small vent in the lid (pic. 7.47).
Pic. 7.48. Battery Visual Check Diagram
Electrolyte Density Check
Pic. 7.49. Electrolyte Density Check
The density of the battery electrolyte changes with temperature. Heating dilutes the solution and reduces the density of the electrolyte. Cooling thickens the solution and increases the density of the electrolyte (pic. 7.49).
With a fully charged battery, the density of the electrolyte should be 1.260–1.280 g/cm3 at a temperature of 26.7°C. If the actual temperature of the electrolyte deviates from the standard value, a correction must be introduced: 4 points must be added to the density value (0.004 g/cm3) for every 5.56°C above 26.7°C or subtract 4 points (0.004 g/cm3) for every 5.56°C of temperature less than 26.7°C.
For example: a hydrometer shows a density value of 1.280 g/cm3 and a thermometer shows an electrolyte temperature of -12.2°C (10 °F). According to the figure below, the measured density value should be reduced by 7 points (0.028 g/cm3). Thus, the reported value for the density of the electrolyte at 26.7°C. will be 1.252 g/cm3.
Calculation formula: 1.280–0.028=1.252.
Pic. 7.50. Charging the battery
Do not measure the electrolyte density with a hydrometer immediately after adding water to the electrolyte. In order for the water and electrolyte to mix and establish a uniform density, or slowly charge for several minutes (current 5 A) battery, or leave the battery stationary for about one hour (pic. 7.50).
Attention! If any battery bank (one or more) electrolyte density differs from the average value by 50 points (0.05 g/cm3) or more, this is a sign of internal damage. In this case, the battery must be replaced.
Pic. 7.51. Scheme of dependence of electrolyte density on its temperature
Visual check of the battery
Turn the ignition key to position «OFF» and turn off all additional electrical equipment.
Pic. 7.52. Disconnecting the battery wires
Disconnect the wires from the battery terminals (first disconnect the wire from the negative (–) terminals) (pic. 7.52).
Remove the battery from the vehicle.
Attention! Take special care if the battery case has cracks or other sources of electrolyte leakage, avoid contact of the electrolyte with the skin. Always wear suitable rubber gloves when removing the battery (do not use household gloves).
Check the condition of the battery tray for corrosion damage caused by acid leakage (electrolyte). In the presence of corrosion, it is necessary to wash the damaged areas with a solution of clean warm water and soda. Scrub damaged areas with a stiff wire brush and wipe with a cloth dampened with baking soda solution.
Clean the top of the battery with the solution.
Check the battery case and cover for cracks. If there are cracks, replace the battery.
Clean the battery terminals with an appropriate special cleaner.
Clean the inside of the battery cable connectors with a suitable special tool. Replace damaged or worn connecting wires and damaged contact latches.
Install the battery in the vehicle.
Connect the leads of the connecting wires to the battery terminals and make sure that the ends of the contact retainers are flush with the ends of the battery terminals.
Securely tighten the nut of the connecting wire contact retainer.
After tightening, apply some mineral grease to all joints.
Attention! When the battery is being charged, flammable and explosive gas is released under the battery cover. Do not smoke or use naked flames near a battery that is being charged or has recently been charged. Do not disconnect live circuits near the terminals of a battery that is being charged. A spark may appear between disconnected wires (in a chain break) and cause an explosion. Keep flammable items away from open batteries.