Yup, after a few years of flying I dented my first lipo. Its a pretty new battery too. I am going to monitor the voltages on it today just to see how it does. Havent noticed any physical signs... Puffyness, heat, etc.
Had one like that with a Fluoreon 3S 2200; the battery ended up charging twice and then wouldn't balance charge anymore. Keep an eye on it; there's plenty of chances for it to puff or suddenly go south in a bad way.
Yeah I kinda wonder if it may be ok, I am still amazed it picked up some damage as it was tucked up in the plane pretty good. And it wasn't ejected...just happened to hit at the right spot I guess.
Right now, I have it stored in a vented ammo can just outside our brick garage. We will be going out of town here in a few days so I won't be able to monitor it NOR do I wanna take it with us on vacation. Much rather do it that way, than leave it in the house while we are gone.
That's likely just the foam end piece it's gone into.
Leave it alone and keep an eye on it, it will be totally fine I'm sure. It would have puffed by now if it's anything major but saying that a puffed battery doesn't always mean bad things.
Don't massage Lipo batteries by the way it can cause more bad than good.
You'd be surprised - the 3S that I have that's damaged, no puffing or anything, just denting and a bad cell. It's set to be recycled since it won't hold a charge anymore, but I have it being drained until it's dead just to be on the safe side (I hooked up a light bulb circuit to it to drain it - when it's plugged in and there's no lighting of the bulb anymore, it's dead).
At least you've got it set aside in a box in case it goes up - smart, safe thing to do.
I have a few batteries that had received a dent and won't hold the charge. One cell will drop faster than the rest, and after about 2-4 mins of flying I feel like I have to take it out to avoid it from brusting into flames.