It’s hard to imagine the level of excitement that occurs when a lipo bursts into flames inside a model. If it’s on the groynd you get a close up view of a 2000* fire burning your model to useless, unrepairable slag.
If it happens in the air you get to watch it crash and start a fire in the countryside. While it’s burning you wonder how large the bill will be for damage and property losses you’ll be responsible for.
If it happens in the middle of the night sitting on the bench or inside your house you can only hope your fire alarm triggers early enough for you and everyone else to get out of the house. If you’re lucky you’ll all make it out and the fire department will arrive in time to save your pets and a few personal possessions. You get to stand out in the street in your PJ’s or underwear because you didn’t have time to get dressed. All your clothes will be going up in flames or be so smoke and water stained they will all be ruined. Of course you get to find a new place to live and with luck your fire insurance will cover most of your losses. Hopefully you have enough vacation time accrued to allow the time needed to get things done and not lose paychecks. If it ignites in the house, the worst that can happen is you’ll burn to death.
If it ignites in your car you can depend on a massive auto repair bill, if the car can be economically repaired. If you’re driving a car more than 5-7 years old it will likely be totaled as the cost of repair would exceed the value of the car.
All that just because the battery was only a little bit swollen but the voltage measures up so it must still be ok to use, right? Why buy a new battery when the voltage still measures good in the swollen battery? Shoot, a new battery is going to cost $80.00-$120.00. Who wants to spend that kind of money? It might cause a cut back on trips to Starbucks or force delaying flying until the battery can be replaced. Now those are serious inconveniences, right?
Fact is, every scenario presented will cost a heck of a lot more than a battery, and every battery that demonstrates any amount of swelling is telling you everything you need to know. They are telling you to retire the battery and obtain a new one. They are not telling you to wait for a little more swelling before taking action, they are saying do it now as from that point forward anything can happen at any time.
So it’s your call. You can ask around various places about how safe it is until someone says it’s ok for now, the answer you want to hear, or accept reality, discharge the old battery safely and dispose of it, and buy another one. Only you know what you can afford to lose by continuing use of a swollen battery.