AGM is a gel in a mat between the plates. It won't slosh at all.
Um, not that I’ve experienced. While there are gel cell batteries, AGM batteries are a different technical approach.
The goal was to make a battery that wouldn’t spill acid. Making the electrolyte into a gel was one solution. But, starting batteries using gel are pretty rare, as the electrolyte electron mobility is pretty slow.
AGM uses a glass mat that is flooded with thin viscosity fluid just enough to saturate it. That makes it cohesive enough to not allow spillage. I did temporarily revive one of these that dried out by prying off the top and adding some water. But, I added too much and it became sloshy. I don’t recommend doing this routinely. And have just gone back to flooded cells as they are easier to maintain, rather than replace more frequently. I’ve gotten poor service life from AGMs that sit long periods without some low level intermittent float charge treatment. But, then all my chargers were intended for flooded cells. I’m not sure they are the best to use for AGMs. So far, I’ve had 4 AGMs go useless sitting in bikes or on shelves unattended or on maintainers, where flooded cells could either be used or revived. There are others that seems to like them more, though.
Cheers,
