LiPos and water?

[Synergy]

A couple of years ago I changed to LiPos on my Tamiya F350 but I've never had the guts to run them submerged, I always swap to my NiMh packs for water sports. So the question is can I without issue run my hard cased LiPo packs fully submerged?

I'm hoping for a definitive answer from someone who has experience of this

[jwscab]

Lipo and water is a NO unless you have doubly made sure they are sealed.

in order to dispose of them, you drop them in water with salt in it. granted, most water is not 'salty' but the reason is to make it an ionic solution, water is slightly ionic without impurities, with them, it is more so.

I wouldn't trust running them wet, even if I took precautions, but that's just me.

[Synergy]

But I thought LiPo cells were sealed that's why they puff up with gas when incorrectly treated you apparently need to puncture the cell before dropping them in salt water for disposal.

[jwscab]

the cells themselves are sealed, the pack isn't really sealed well, the conductors can allow current to pass through an ionic solution.

I don't believe you are ever supposed to puncture a pack.

[Synergy]

This is a quote from the British Model Flying Association on the disposal of LiPos:-

"Disposal of LiPo batteries:
Put the pack in a safe open area and connect a moderate resistance across the cell terminals until the cell is completely discharged.
CAUTION: The pack may get extremely hot during the discharge.
Puncture the plastic envelope and immerse in salt water for several hours.
Place in your regular rubbish bin.
By Jan Bassett (BEFA)"

Do the cells we use have enough oomph to short through none saline water?

[jwscab]

I've never punctured them, but it should be relatively safe after fully shorting the cells

they will discharge without salt, but much lower current density. but the risk of have a cell that can leak water would provide a pretty dangerous situation.

the problem is that lithium metal does not like to be exposed to water or air, it will readily combine with oxygen, so you try and prevent that. I believe once the cell is completely discharged, all the lithium is combined.

[kaiser]

i use dielectric grease on the contacts if i know it's going to get wet. never had a problem.

[illshou]

The individual cells themselves are all waterproof. The problem aparently is that some manufacturers plasce the cell contacts very close tougether and that water can actually short the cells out. I personally know a guy that always runs his lipos in, under and around water and never has had a problem. But I'm not sure if I would chance it especially with the cost of some lipos and the danger they present.

I do believe that maxamps makes a waterproof series of lipos.

[klavy69]

I've submerged several lipos in water with not problems. Reminds me...gotta fix the hull on my boat before I try that again. Same batteries get hosed off in my slash 4x4 after a mudfest. Hosing isn't submerging but I've deep sixed several lipos where I had to swim to get the boat back...another story
Todd

[shirochanwrx]

I've submerged several lipos in water with not problems. Reminds me...gotta fix the hull on my boat before I try that again. Same batteries get hosed off in my slash 4x4 after a mudfest. Hosing isn't submerging but I've deep sixed several lipos where I had to swim to get the boat back...another story
Todd

That's reassuring.

What brand Lipos do you use?

[klavy69]

What brand Lipos do you use?

cheap .
Got a turnigy that was out of sight for pry 5 minutes, a no namer that I use for my daughters truck, swang hobby 3 cells that I hose off in the slash, and I think the other one that sunk was a flyermate. But I neglected to say that I pack all my electrical connectors with di-electric grease like mentioned above when they are new after installation so that might be my reason for no shorts.
I'm not saying go drop them in a bucket of water but I personally haven't had any problems with water and lipo.
Todd

[THEYTOOKMYTHUMB]

...I've deep sixed several lipos

Lucky lipos...

[Jedi Master]

I use Lipo's in boats, and have had a few submersions with them. If they are properly sealed, you can simply dry them off and have no issues, but 'properly sealed' is very difficult to achieve. Each single Lipo cell is made up of hundreds of layers of very thin lithium. In between each layer is a coating of silicon polymer. The danger with Lipo's is that; if the battery gets too warm, the silicon melts and the charged layers of lithium short circuit against themselves. It only takes one layer to make contact with another and the heat this produces melts the next layer of silicon. You then get a very fast chain reaction as the heat transfers through the pack melting each layer and causing more short circuits/heat. This is why lipo's 'go off' with a bang.

Nimh's are different by physical design, so when they get submerged in water they simply dis-charge. Dry them out, re-charge and you're back in business.

Lipo's are not designed for this, so only a perfectly sealed pack will survive.

It's an individual choice, but my advice would be to stick with Nimh's if you are regularly going to get them wet.

I use 22.2v 5000mah lipo's in my boats, and this is what happened when one got properly wet;




This little accident cost me the best part of £2k. I waited 15 minutes before pulling the hull out of the water and even then, the water-line was sizzling from the heat that was transferring through the hull.

Water and Lipo's DONT MIX!!!!

[Synergy]

Hmmm I guess I can't deny the overwhelming photographic evidence

I'll swap the truck back to NiMhs and keep the LiPos for the racers and car park runners

[klavy69]

I'm guessing I have got really good (but cheap) lipo packs that haven't gotten too hot or I've gotten really lucky then. Makes me wanna go hmmm next time
Todd