I think you mean the acid in the batteries ?|Using a pH meter. ;)
Virtually all automotive batteries nowadays are nominal " 12V " batteries, but will measure up to 13.6V when fully charged.
Chemical change
They utilize the power of the force concentrated through a crystal, not batteries.
Baseballs don't require electronics so you don't need batteries for them
change the batteries
Yes
The keypad doesn't take batteries , the remote takes a battery or batteries
You can find discounted batteries at http://www.onlybatteries.com/. This site has specials that change daily and you can find your discounted batteries too.
how to install batteries for schwinn 222
The Macy's on 34th St. NY changes watch batteries. They do charge you.
AAA batteries measure one centimeter wide.