If you must then opt for a less convenient open-cell spare battery, we recommend checking the battery fluid level from time to time. The battery fluid consists of sulfuric acid diluted with distilled water. High ambient temperatures or a faulty voltage regulator reduce the proportion of water in the battery acid. During long periods of inactivity, the battery automatically self-discharges. This can also lead to a lack of water, as can deep discharge due to an external current consumer (e.g. a cooler box connected to the cigarette lighter). Always top up with distilled water only - tap water, like boiled water, contains conductive salts and other minerals that are harmful to the battery.
In batteries that are not subject to maintenance, the evaporated liquid condenses above the cells and drips back into the battery.
Stages of work
The acid level should at least reach the MIN mark on the body (the upper edges of the plates should be well covered).
If the acid level is too low, top it up by unscrewing the plug or pressing it with a screwdriver.
Top up the charged battery fluid level to the top line (about 15 mm above the plates) with distilled water.
If the battery is very discharged, top it up only until the plates are covered - the acid level rises significantly when charging. If necessary, top up the liquid to the upper mark with distilled water after charging.
Never overfill the battery - otherwise acid will come out of the plugs or side vents. This leads to corrosion or the formation of acid crystals on the surface of the battery and around its location. Carefully remove the salt crystals with a brass brush and then wash the surfaces with plenty of water. Do not forget to disconnect terminal 31 (minus pole) of the battery beforehand.