See also: * https://en.wikipedia.org/wiki/List_of_battery_sizes https://en.wikipedia.org/wiki/List_of_battery_sizes * https://en.wikipedia.org/wiki/Comparison

See also: * https://en.wikipedia.org/wiki/List_of_battery_sizes https://en.wikipedia.org/wiki/List_of_battery_sizes * https://en.wikipedia.org/wiki/Comparison_of_commercial_battery_types https://en.wikipedia.org/wiki/Comparison_of_commercial_batte... And if you are interested in the history of tube electronics: * https://en.wikipedia.org/wiki/Battery_(vacuum_tube) https://en.wikipedia.org/wiki/Battery_(vacuum_tube) These Wikipedia articles were a lifechanger when I found them. I literally tried purchasing various types of batteries after reading them... It taught me that 9V battery may be preferable for some analog circuitry (meters, amps, etc) but often is a terrible choice for most DIY electronics due to its low capacity, that good Ni-HM cells with low self-discharge rate exist, that Lithium type have the highest capacity, lowest self-discharge rate among all AA cells, but with a high 1.8v open-circuit voltage under no load (and doesn't even drop below 1.6v when they are discharged) that may be a problem for ultra-low power applications, that Zinc-Air cells have the highest capacity among all coins cells but self-discharge quickly when exposed to air, etc...