TheWW1FlyingAce
Member
Friends, Romans, FliteTesters, lend me your ears, I come to bury salt water LiPo disposal, not to praise it.
Yes, my friends, salt water LiPo disposal is a bad, bad idea. Sure, on the surface it seems like a good concept - after all, salt water conducts electricity, so it makes sense that dropping the battery in salt water will discharge it. But the devil is in the details and the detail, in this case, is electrolysis. You see, salt water and electricity have an amazing talent in the field of dissolving metals, including the tabs on the LiPo cells that actually conduct the electricity. And once those tabs are dissolved, no more discharge. That's the real problem - the tabs on the cell tend to dissolve before the cells are completely discharged, leaving you with the worst of both worlds - a cell that's still got a charge, and no way to discharge it.
"But", you ask, "why does everyone recommend using a salt water bath to dispose of LiPos? Where did this recommendation originate?"
To answer that question, we need to take the WABAC machine back to the dark, early days of using LiPos for RC. Days when an 8C pack was an expensive miracle, and to get more than 1300mAH you needed to run packs in parallel. Days when the concept of balance charging was just starting to take hold among enthusiasts, and those who did balance their packs used external balancers after charging with their non-balancing chargers. Days when LiPo fire reports seemed like an almost daily occurrence.
Back in those days a very smart gentleman named Fred Marks (who went on to found FMA Direct and designed the excellent Cellpro series of chargers) wrote a disposal document for Kokam, one of the early high-end LiPo manufacturers. In this document he recommended disposing of the batteries in salt water. BUT, and this is a very big BUT, the document also specified that the envelope of the cells needed to be cut open so the salt water would get inside the pack and neutralize the electrolyte.
Slashing the cell to allow the salt water to neutralize the electrolyte is an effective way to dispose of a LiPo battery. BUT, and this is an even bigger BUT, slashing the cells of a charged LiPo battery is dangerous, as an early RC experimenter found out the hard way. The battery essentially exploded in his face and he was lucky to escape serious injury.
Because of the danger of slashing the cells, Fred Marks no longer recommends using the salt water bath with cell slashing. And he's always been adamant about the fact that a salt water bath without cell slashing is worse than useless (because the cell tabs will dissolve long before the pack is fully discharged). So, there is no good reason to use a salt water bath to dispose of LiPo batteries.
So, what is the safest way to dispose of LiPos? Enter the humble incandescent 12 volt automobile taillight bulb. If you have any skill at all at soldering (and you'll need it anyway if you do anything with electric RC) it's very easy to solder some wire to the contacts of a 12 volt automobile taillight, add whatever your battery connector of choice is to the other end and insulate it with electric tape or heat shrink. To dispose of your battery, just plug the battery into the taillight, put it somewhere where it's safe (I use the holes in a cinderblock with a plastic baggie full of sand above - if the battery blows the baggie will melt and the sand will pour over the battery) and leave it until the bulb goes out. Then leave it for some hours more, check the voltage to make sure the battery is completely discharged, cut of the battery connector, strip the wires and twist them together. Then dispose or recycle the now completely safe battery. A single taillight bulb will work for up to a 3S pack of any size, use two taillights in series for 4S or more.
Hopefully I have dispelled the myth of salt water LiPo disposal, and I hope that this helps people who are looking for a safe way to dispose of their LiPos.
Yes, my friends, salt water LiPo disposal is a bad, bad idea. Sure, on the surface it seems like a good concept - after all, salt water conducts electricity, so it makes sense that dropping the battery in salt water will discharge it. But the devil is in the details and the detail, in this case, is electrolysis. You see, salt water and electricity have an amazing talent in the field of dissolving metals, including the tabs on the LiPo cells that actually conduct the electricity. And once those tabs are dissolved, no more discharge. That's the real problem - the tabs on the cell tend to dissolve before the cells are completely discharged, leaving you with the worst of both worlds - a cell that's still got a charge, and no way to discharge it.
"But", you ask, "why does everyone recommend using a salt water bath to dispose of LiPos? Where did this recommendation originate?"
To answer that question, we need to take the WABAC machine back to the dark, early days of using LiPos for RC. Days when an 8C pack was an expensive miracle, and to get more than 1300mAH you needed to run packs in parallel. Days when the concept of balance charging was just starting to take hold among enthusiasts, and those who did balance their packs used external balancers after charging with their non-balancing chargers. Days when LiPo fire reports seemed like an almost daily occurrence.
Back in those days a very smart gentleman named Fred Marks (who went on to found FMA Direct and designed the excellent Cellpro series of chargers) wrote a disposal document for Kokam, one of the early high-end LiPo manufacturers. In this document he recommended disposing of the batteries in salt water. BUT, and this is a very big BUT, the document also specified that the envelope of the cells needed to be cut open so the salt water would get inside the pack and neutralize the electrolyte.
Slashing the cell to allow the salt water to neutralize the electrolyte is an effective way to dispose of a LiPo battery. BUT, and this is an even bigger BUT, slashing the cells of a charged LiPo battery is dangerous, as an early RC experimenter found out the hard way. The battery essentially exploded in his face and he was lucky to escape serious injury.
Because of the danger of slashing the cells, Fred Marks no longer recommends using the salt water bath with cell slashing. And he's always been adamant about the fact that a salt water bath without cell slashing is worse than useless (because the cell tabs will dissolve long before the pack is fully discharged). So, there is no good reason to use a salt water bath to dispose of LiPo batteries.
So, what is the safest way to dispose of LiPos? Enter the humble incandescent 12 volt automobile taillight bulb. If you have any skill at all at soldering (and you'll need it anyway if you do anything with electric RC) it's very easy to solder some wire to the contacts of a 12 volt automobile taillight, add whatever your battery connector of choice is to the other end and insulate it with electric tape or heat shrink. To dispose of your battery, just plug the battery into the taillight, put it somewhere where it's safe (I use the holes in a cinderblock with a plastic baggie full of sand above - if the battery blows the baggie will melt and the sand will pour over the battery) and leave it until the bulb goes out. Then leave it for some hours more, check the voltage to make sure the battery is completely discharged, cut of the battery connector, strip the wires and twist them together. Then dispose or recycle the now completely safe battery. A single taillight bulb will work for up to a 3S pack of any size, use two taillights in series for 4S or more.
Hopefully I have dispelled the myth of salt water LiPo disposal, and I hope that this helps people who are looking for a safe way to dispose of their LiPos.
