You raise an important talking point...
The AIs need to share their resources on most maps so that they do not waste mass. Usually one AI has an excess between 3mins and 10mins game time.
Now I may be wrong in thinking that just allying the AI does not cause them to share, and that its only when the human team share that the AIs will share.
I think I read this on Sorian's GpG post and have done it ever since. We could test it out to be sure. The in-game setting is tricky to set because the visual indication is ambiguous, as its hard to tell whether you are in 'share' or 'none share' mode. On top of that there has been a new addition to the lobby options that allows 'share units on death' that confuses the issue further.
In any case I thought it would be normal for human team members to share resources to ensure you partner does not have an energy stall.
roj