Many electric utilities have substations that have 60 very large lead flooded cells in series to make 130 V DC to run all the equipment that monitors the state of all of the power lines into and out of the substation, communicate with the main control room of the utility, provide output control signals to control switching of huge high voltage circuit-breakers in the substation, and provide power to operate the huge high voltage circuit-breakers. When the power goes out this equipment must still operate and control what stays connected, what gets disconnected, and what gets brought back up when sections that may contain the fault have been disconnected.
Electrically all 60 are in series. Physically it is almost always set up as two rows of 30 in series and the electrical beginning negative is on one end, and the final positive is on the end of the row next to it and actually fairly close to the beginning negative.
Usually the case is made of transparent plastic and you can see small bubbles on the plates.
These huge batteries are always on a trickle charge, and last a very long time, like 20, 25, or even as long as 30 years depending on the size and use. There are a few different size used depending on the demand and size of the substation. But at any given substation all the cells in the stacks are the same size.
When one of these batteries fail open and the 130 V DC is lost during a outage, very bad things can happen. One such case cost 10 out of 11 huge transformers, and much of the big metal pipe used to carry the current, to be destroyed. And those transformers cost one million each, and are special order and take a while to get produced, and even transporting them is a major chore. They are very big and heavy.
These batteries ain't cheap. Which may be why some times the penny pinchers are reluctant to replace them. In the case where failure caused major losses, the penny-pinchers who ignored multiple requests month after month to replace the worn out batteries tried to hang the blame on the person in charge of the department, who among other things oversees the maintenance of those batteries. He produced copies of all of his past request for replacement of those batteries, and was able to keep his job.
After that, the penny-pinchers were very liberal about spending money to replace old batteries in other substations.