Maintenance free battery
Virtually maintenance-free batteries do not have screw-on cell plugs. Checking the level and density of the electrolyte for these batteries is not necessary, because the evaporation of the electrolyte does not occur.
These batteries usually have a so-called «magic peephole» (see arrow in illustration 9.0), which is an optical electrolyte level indicator. By changing the color of the optical indicator, the electrolyte level and the degree of battery charge are determined.
9.0. Optical electrolyte level indicator
Before checking, it is recommended to lightly tap the pointer with the handle of a screwdriver to remove air bubbles that affect the color of the pointer.
- the color of the optical indicator is green - the state and charging of the battery are normal;
- the color of the optical indicator is black - an uncharged battery or charging is too weak;
- the color of the optical indicator is yellow or the optical indicator is colorless - a critical electrolyte level has been reached. The battery needs to be replaced.
Conventional battery
A conventional battery differs from a battery that does not require maintenance in that its top cover has cell screw plugs or a bar that closes the cell openings. This battery requires regular checking of the electrolyte level in the cells, for which follow these steps.
The electrolyte should cover the battery plates. The thickness of its layer above the plates should be approximately 5 mm. In some batteries, the electrolyte level is visible through a transparent case. In this case, it should be between the MIN and MAX marks on the housing. For batteries with an opaque case, the electrolyte level should be at the lower edge of the protrusion in the vent hole.
1. Unscrew the cell plugs using a wide screwdriver or remove the plug strip by carefully prying it out with a screwdriver.
2. Top up, if necessary, with distilled water through a funnel, bringing the electrolyte level in all cells to normal.
3. Screw in the cell plugs or close them with a bar.
4. Charge the battery and check its voltage under load.
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