rjxj wrote:
Check the voltage on your battery tender and keep an eye on the electrolyte level. Always over the plates but never above the bottom of the split ring. If you look in the hole as the water comes up it will form what is called a cats eye when it just starts to contact the edge of the vent ring. I always stay below that or you will get acid on the top of batteries and more corrosion problems. Wear eye protection when doing it as very small splashes of electrolyte will pop up. I dont know your experience with batteries so will just go on a little more for your safety.
When the battery is charging or heavily discharging it gives off hydrogen gas. if a spark is near the top of the battery it can blow the top right off it. Be very careful about creating any sparks or dropping a wrench on the posts. Best battery procedures include safety goggles and a water bottle for flushing your eyes.
So if I understand you correctly, you don't want to see the "cats eye?" I've always filled just enough until the cats eye appears. So in reality, it would be better to get as close as possible, but not actually touching?