Lithium Batteries and Seawater

Water and electrics don't mix...

Especially so for salt water!

Water and electrics don't mix...

Thanks, but I wasn't planning to stand in the ocean with a hairdryer

To be more specific- if a lithium battery (high voltage and amps for electric vehicle) is immeresed in seawater does the seawater provide a dead short or will the "resistance" of the seawater let the battery energy dissipate? With a dead short the energy (≈20kW) is released so rapidly the battery runs away and overheats resulting in a thermal event.

No the sea water wouldn't provide a dead short for low voltages.

The same as a car battery can quite happily continue functioning even under the bonnet (hood) of a car driving in the rain.

But you mention a high voltage with plenty of capacity... depending on the voltage the battery could be overloaded by the low impedance of the sea water and the duration of submersion...

If the battery volts is below 50 volts (at a guess) then it should be okay in that it wont explode etc... it will discharge though.

John.

With a dead short the energy (≈20kW) is released so rapidly the battery runs away and overheats resulting in a thermal event

Yeah! Probably.

I've seen hundreds of lead/acid wet cell batteries after sinking in boats. If the battery was in good condition it will mostly suffer eaten-away terminal posts- not completely though. I'm talking 12v, 200a/h . Higher voltages would blast the posts right off I would think. Seawater is a better conductor of current than most people give it credit for. Depends where in the world you are. Salinity, minerals, water temp, etc.

I'd think that the resistance would controll the discharge enough so as not to have cells 'blow up' (out). Again, depends on the voltage too

Sometimes 'miracles' have happened and I've been able to simply wash out the cells with clean water, add new elctrolyte and put the battery back into service. No, not in the boat, in the shop, or in the trucks.

There, you can get a cab home. Not so from out at sea

Cheers,

Stu.