The energy required is equal to its Time * your drain, most of the times you can look at survival Time on the bottom right, if that is higher than the completion Time of the action that means you will be able to complete it, I guess we can be a bit more descriptive, like: Not Enough Energy (150 current / 200 required)
as for searching batteries, I know, it is a pain for me as well during testing, but it is to avoid people dying from searching batteries while they could have taken one, also it makes sense, why search another battery if you already can take one in front of you? btw you need to search them only once, so it is for the greater good