Optimal Water Level in a Battery: Understanding Measurements and Indicators

Hello
I would like to know how much water I should add to the battery.
I don`t know anything about this and I wanted to ask you for advice. I`ve read a bit but I`m still wondering. In the attached drawing I have marked how much water is currently in the battery. And from what I`ve read, the level is probably good, but I`m not entirely sure, because when I look into the holes from the corks, in each cork there is a piece of plastic that goes down from the cork (something like the letter L) and it ends at about 1 cm higher than the water level marked in the picture. Or maybe this plastic is a water indicator?
I am waiting for your help.
regards

The most important thing is that the plates are completely immersed. It is known that you need to pour it a little higher (1 cm) so that the slabs are still submerged when tilted slightly.

The battery contains electrolyte, not water. What caused the loss - evaporation or leakage?
If evaporation occurs, add distilled (demineralized) water to the level of these "L".

Hucul wrote:

The battery contains electrolyte, not water. What caused the loss - evaporation or leakage?
If evaporation occurs, add distilled (demineralized) water to the level of these "L".

Well, I know it`s electrolyte, it just said it was water, but I understand the full professionalism of my colleagues. The water loss is due to evaporation, as there was no leakage. now I had problems starting the car, and that`s why I wanted to top it up and check the electrolyte level while doing so.
Thanks for the help. I will add water to the level of these plastic indicators.

and one more question - should I charge the battery with the caps open or closed? because what I read, everyone has a different opinion.

Unscrewing them, or at least not tightening them by force, certainly won`t do any harm.
It is also a good idea to ensure that charging takes place in a ventilated room.

Hello
Only add water if there is a loss during normal operation of the car battery, no electrolyte unless it leaked during damage or overturning.
Water evaporation is a natural process that involves various factors, e.g.
warm summer, too high charging voltage via the alternator, above 14.5V
If, after unscrewing the caps, the plates were on the top, you should take into account that the battery will not last long because the lead reacts with the air and crumbles from the plates, settling on the bottom and causing a short circuit. :|

Charging process:
1. unscrew the caps and pour water into the "L" (spouts) - leave them unscrewed
2. connect the rectifier and charge with a current of 1/10 of the battery capacity for approximately 12 hours
3. after a few hours (3-4), the electrolyte should start to react and bubble
this is a normal reaction. (it would be good to check the density of the electrolyte)
4. charge it for 12 hours, you will definitely notice a loss in individual cells
5. disconnect it and add water to the "spouts" and plug it in for 1 hour.
6. leave to cool, screw on the caps, wash any remaining electrolyte around the caps with cold water

Good luck