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Water ingress in the battery compartment


(JGreg Kherian) #1

Hi,

after a dive, we found out we had some water ingress in the battery compartment, see pictures of battery connectors below.

The battery was not particularly hot and would still charge later on. I havent dived again yet, so not sure if/how much the battery capacity may be affected.

Any safety issues? recommendation?

Thanks!



(Maurizio) #2

I would personally try to find the cause before further divings. You might try to clean around orings and put some grease on them. Then take a rope a do a test dive only with the compartment without battery (unmount it from the ROV), and check after the dive if there’s water inside. It might just be some dust or hairs that creates the problem.


(Adam) #3

Hi JGreg,

That doesn’t look good! What happened and how did the leak occur? @mau792 is correct, its definitely possible that there may have been some debris on on the o-ring groove that could have comprised the seal. Was it saltwater or freshwater that got inside?

Unfortunately, there isn’t much that can be done for the battery now. Water shouldn’t immediately cause a short, but it will make the battery corrode quite severely internally. We have gotten batteries wet in our testing before, and they have corroded significantly- we discontinued use and threw them out when we noticed what had happened. My recommendation would be for you to do this as well is the battery was completely doused. If just the connectors got wet and the rest of the battery is fine, you can just cut off and replace them.

-Adam


(JGreg Kherian) #4

Thanks for the replies!

my question was more towards whether there was any risk to try and continue using the battery.
I ll clean or replace the connectors and see.

As for the cause of the leak, I m not sure yet, but i ll clean and re grease seals and clean sealing surfaces and test again.

There was about 1cm of water in the compartment with a thin layer of white-greenish foam on the surface after approx 40 mins dive down to max 17m.


(Adam) #5

Hi JGreg,

In that kind of situation, we have always immediately discontinued using the battery and disposed of it. The entire structure of the battery will corrode and if you continue to use it, I have no idea what will happen. It is not safe to use it anymore.Unfortunately it looks like your battery has been destroyed, and I strongly recommend you dispose of it.
-Adam


(Todd Sparkes) #6

Dispose of it it a proper manner such as a recycling facility. Throwing it in the trash also produces hazards.


(JGreg Kherian) #7

Hi adam,

Noted and agree, thanks for your reply.


(undersearobotics.com) #8

FYI, when I had a couple LiPO batteries “puff” I learned that the recommended method of disposing of them is to first let them soak (for as long as a month) in salt water. After which they are literally neutralized (no charge at all) and can be disposed of in the trash.


#9

About soaking the battery in salt water, I can provide a bit of personal experience. We had a timelapse camera deployed in a BlueROV enclosure and powered by a BlueROV battery. Because we were in a rush, we only did a vaccuum test (successful) before deploying the system for 5 days at 40 m depth.
apparently there was a small leak, that produced a shortcut (records stopped after 6-7 hours).

When I recovered it 5 days later, water was filling half of the enclosure, was milky white (I guessed due to the battery leaking) and the internal pressure was enough to bend the metallic parts securing the the enclosure closed (and on the way up, with the water pressure decreasing the metal parts gave up and the enclosure “popped open”).

All this to say that is you plan to soak LiPo batteries in salt water, expect some degassing and some leaks in the saltwater (and thus appropriate disposal).

Epilogue: we now received the fixed timelapse camera and we will start very progressively testing it (dry lab first > freshwater tank > shallow sea short time > long time > deep short > real deployment)