Is there a maximum size to the inventory in Borderlands 2?
I've noticed that I have been able to increase my effective backpack/inventory space by receiving quest rewards and never selling weapons/items. If you get an item from a quest when you have a full backpack, you go from 27/27 to 28/27. Since backpack space+bank space are annoyingly small to me, I've been using/abusing this feature to get a backpack space of more like 36/27 or more. Is there a limit to how far that I can take this? I haven't noticed any downsides; I just swap weapons from my hands to the one on the ground if I want to pick one up (this doesn't increase the number of things I'm carrying, it just allows me to still acquire loot by trading it with the stuff in my backpack). Is there an upper limit to the backpack size with this technique, or can I effectively increase my backpack space ad infinitum?
For reference, my current backpack size looks like this:
Update:
I now have a backpack size of approximately 150/27, and am not experiencing any difficulties, aside from occasional issues when trying to trade with other players (I seem to have to give as many items as I receive, or the other player's game complains that my backpack is full).
According to this thread:
Backpacks are stable up to 500 items in your backpack and 8 equipped, and probably goes further, I didn’t take it past that.
It's likely limited by memory only.
It seems the inventory of Borderlands 2 is buggy in general, as the linked thread was started because of another way to exploit it; by buying back items, which will go straight to your backpack.
The exploit does come with some caveats, though:
Overfilling comes with problems though. Vendors only hold 20 items, so if you go for 500 it will be a struggle to pick up guns that drop above your level, or customisation skins - you’re stuck with what can be exchanged in an active slot. I imagine you could drop all your items till you get an empty slot and then do it over again, but that would drive me crazy. Also, it might often rely on you being close to a vendor to do this, which isn’t always the case.
and
If you do this the way I did it [buying back items], you will lose money, I think due to Seraph sell/buyback values. I lost about 30 million while adding 300 new backpack slots.