system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why do electric vehicles have one big battery that's hard to replace once it's expired, rather than lots of smaller ones that could be swapped out based on need (to trade off range/power/weight)?
gpt
More often than not, they DO have a lot of smaller batteries that can be swapped out based on need.

It's just that, eh, the batteries are a safety hazard for rescue services when the cars are in accidents, and to make them less of a hazard they are combined into a large container that is comparably good at confining the hazard.

There are other reasons to, such as thermal control of the batteries and weight distribution concerns.