Fleet capacity - end game

That's not a flaw. That's a 3v1 fight. It shouldn't feel fair if the game is designed correctly.

Even so, in that situation he shouldn't have a max-capacity fleet by the nature of his resource situation (3 planets). So you can attack with a smaller fleet and then fight off his friends with the main chunk of your fleet (in addition to fixed defenses, which cost no fleet capacity).

The flaw in Fleet Capacity is more that you can't reduce it - so your upkeep can be crazy high and you don't have the option to reduce your capacity (although perhaps this is automatically handled in the actual amount of upkeep you're charged? I kinda doubt it though, since researching the tech increases your upkeep even before you've filled out the capacity with new ships.) It's not a particularly graceful game mechanic to get yourself into a situation where upkeep eats up a huge chunk of your income, and you're not even using it all.

They could fix it by letting you set a "capacity slider". The max value would be your highest research, and the lowest value would be your current fleet size (plus queued ships).

Or they could fix it even better by just automatically changing your upkeep to however much capacity you're currently using (so below 200 used, you pay nothing even if you have the final tech).

The max fleet-size should be linked to the number of planets and/or the advance in research, I think.
You have a point too. If I loos all my ships, why pay for the upkeep?

Even if you lose the ships, the logistical infrastructure is still in place and cannot be easily dismantled, which is the idea behind having it as a sequential tree.

That being said, there is a problem with large endgame economies being handicapped by fleet logistics.

I don't mind that you can't scale/throttle your economy back down if you loose a massive number of ships, it makes the decision to go ahead to the next tier more important/risky. But that said, I definately think the number of ships/fleep points given from each tier needs to scale with the number of stars/planets in the game.

He only has 3 planets left. Almost all of his economy is gone, agreed lot of logistic needed but the infrastucture isn't there anymore!

It seems no problem with shorter (5+ hours ) games, but I definitely won't play above this anymore.

That's incorrect.

Upkeep is a constant expenditure. There's no reason an empire would continue funding unnecessary support mechanisms. It would ditch the support personnel and cease refueling/maintaining its support vehicles if that support was no longer needed.

More importantly, it doesn't flow well as a gameplay mechanic and so it's not as fun as the way other games handle this issue. That alone is sufficient reason to change the system up a little (all that needs to change is the backend calculation of your upkeep cost).

That's not enough. My enemy has only three planets but as many ships as max-capacity allows. In the endgame credits are no problem (I had about 200.000) so he can easily pay the upkeep cost. But in my opinion he should not be allowed to have as many ships.

Seen from another angle: I have 50 planets he has three and there is no difference in the endgame - worse: since I have to defend other places of my empire too, it is not even equal.