Lead/acid batteries all produce the same voltage, since it's based on a chemical reaction (and not the size of the battery): 2.1 volts per cell. 3 cells = 6.3 volts, 6 cells = 12.6 volts, etc. This is one reason why small lithium, rechargeable, and carbon core etc. batteries are not interchangeable in small electronic devices - they're not exactly the same voltage since the chemical reactions differ.
The Jalopy Journal
