Anyone interested in a subsea battery?

A subsea battery is essentially a type of lithium battery suspended in a special pressure compensation fluid like these guys below. The one I’ve built is more on a hobby scale though.

Bluefin Subsea Battery

The advantage of these is your not limited to the space you have available in a pressure vessel, and you don’t have the cost of a dedicated pressure vessel.

I’ve been working on a low cost glider, and built a subsea battery for it. I’m wondering if other folks would find something like this useful for their projects as well.

I bet it would be fun to know what Bluefin charges for theirs!

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That very interesting! You had to find a battery with no internal spaces or gas. What specific type of lithium chemistry did you use? LiPo? And have you tested to depth?

I’m using a pouch type 3S LiPo battery with a pressure compensation fluid, and I’ve pressure tested to 350m successfully.

The next goal is too see if I can get a BMS to survive this testing as well, and to configure my pressure chamber for cycle testing.

Interesting. So, you are assuming the battery has never been overcharged (thus producing gas bubbles) and taking advantage of the flexible container. I may bag one in some oil, strap that on for my camera’s next dive and see if the battery pack comes back undamaged and still charged.

I’ve honestly never thought about the gas bubbles. I’d assume they would only become a problem after pressure cycling it a bunch of times. I just used a bag of oil for the first tests as well, but something commercial would benefit from not being as flammable. Please let me know how your tests go!