system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are battery arrays (ie: AA-style) designed to alternate the + and the - positions when lined up next to each other?

I mean, in rechargeable packs, you line them up identically, but then you put them in a remote control and they have to alternate. Why?!

Edit: Thanks all! Happy to learn this random bit of information after a lifetime of blindly accepting it!
gpt
Because it's a simple way to wire the batteries in series rather than parallel.  

There are two ways to connect batteries.  In series (which adds the voltage) or in parallel (which adds their amperage).  Many battery powered devices could simply use a single larger cells for more amperage, so wiring in series (to increase the voltage) is much more common.   

Putting the batteries in alternating sequence means that one end of the array only requires a single connection between the two ends to maintain them in series.