My first Lipo incident.

[Lil Giants]

Yeah, I've done that more than once, left the switch on in the 850 & killed a 4s batt. I don't believe there is any concern with lipo fires from leaving a switch on, running the lipo completely dead. The risk is rather trying to recharge them again & everytime after that!

Lipos are pricy but compared to the damage they could cause if something goes wrong with recharging or during use .... discard it & get a new one.

I use my .22 rifle to blow up my ruined lipos from a distance, then chuck 'em in the burning barrel. I've had one burst into flames after shooting it, 3 or 4 others didn't do anything.

[FlyingBeagle]

One misconception I see a lot is that lipos blow up. Lipos don't explode, they just burn very rapidly. Make sure that there is nothing near a suspect Lipo that is combustible as the fire will be intense, but pretty localized.

The safest way I know of to dispose of a Lipo is by first discharging it all the way. I do this by running it down very far and then putting it in a bowl of salt water to completely discharge. This removes all of the stored energy so they become fairly benign. Once discharged you can puncture it safely. If you puncture a Lipo that still has a charge that is when you get the fireworks. And if it is fully charged it can be quite a show.

You can save a Lipo that has been completely drained by charging each individual cell slowly with a non computerized charger until they all meet your digital chargers minimum voltage requirement. Then balance charge from there. I agree with Joe above though that the future risks are not worth the money saved.