[Unklejoe]

I just want to point out that batteries are often connected in series in regular devices.

Many devices where there are two AA batteries (TV remotes, etc...) usually have the batteries wired in series. They need to do it to get the voltage high enough for some of the components.

Additionally, many batteries are actually made from multiple smaller batteries wired in series internally. For example, some 9V batteries are actually just 6 regular 1.5V batteries wired in series.

Of course, in these configurations, they generally discharge at a similar rate.