And it's not just your run of the mill batteries either.
I remember once having to open an alarm panel with an angle grinder, the lid had welded itself to the cabinet. I wish I had photo's to show what the inside of the panel looked like after the battery leaked. ( still have nightmares ) PS: Wasn't one of our systems.
And watch out for UPS batteries, I used two Newton Power 7.2 ah 12 volt in my office UPS 1000 VA, and months later got horrific headaches when on the computer.Fortunately we had a power out and the UPS died without warning, I immediately checked it and found the carpet all wet around it, both batteries had leaked and destroyed the surrounding carpet, toxic gases as well. First and last time for Newton Batteries.
I now have shallow plastic containers under all UPS's and also only use Yuasa batteries (5 year warranty )
Muttley