If I use the mini kegs for a 5 gallon batch, can I just store the beer in them and then force carbonate when just before I intend to use them. I would rather force carbonate than use priming sugar but will only use one at a time.
"A flute with no holes is not a flute......
....... and a doughnut with no hole is a Danish."
The real issue is that since the mini-kegs aren't rated for a ton of pressure, force carbonating is really easy to screw up with a mini-keg. They aren't really rated for the pressures that homebrewers use for force carbonation (30psi + rocking, for example) as they are meant to be cheap and disposable.
There are guidelines on this forum for how much priming sugar to use with a mini-keg that seems to work well.
I've had mine at 25psi for the past week without issues, as a test only. I'm doing this mainly for storing half batches, which will be at 10 -12psi. When I need to tap it, I pull out the valve and hook it up to my keezer using (pic #15).