Puffed lipo.
 

One cell of a two cell battery has puffed so much it's cracked open the hardcase and got worse and worse.
I've just cut the wires and balance lead off but how can I make it safe?
I've heard a bucket of salt water works. How long do I leave it?
Any other options?
I'd leant it to someone who I think discharged it in their car, left it a couple of days and didn't balance charge it when charging it back up from empty!
Lucky it wasn't expensive but worked well and will be missed.
:(

Saltwater bath is unnecessary, if you are brave enough to fully discharge the pack (perhaps with your charger or with a bulb discharger) that will get the vast majority of the energy out and it won't pose a risk.

Although to be honest a similar thing happened to me the other week and I just took the pack straight to the council dump.

i had a battery that bulged and i discharged it using my homemade discharger i made, then disposed of it when fully dead in a battery disposal box in my local sainsburys car park.

i used a standard duratrax motor connector attached to my bulb holder,
cut edges of plug off to reveal the 2 pins,
thay are a perfect fit for the balance lead,

i use a 6v bulb for it,

see pics

So over discharging them doesn't cause any issues, just makes them safe?

yep.just flatten it Phil and put into recycle box,give it to me if you like,we have a box at work.:)