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Melted battery holder
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Melted battery holder

by MightyDrake on Sun Oct 14, 2018 6:09 am

I posted a few years ago asking about using a MintyBoost in a very high humidity environment. I finally found a camera small enough to fit in my hockey helmet cage that takes a USB power source. The MintyBoost is just *barely* small enough to fit in my helmet.

I slathered a good deal of the silicone conformal coating onto the board. I also taped a USB extension onto the connector, and tried to tape up the gap in the box. And, most games, I would wrap tape all the way around the can.

It worked fine for a dozen games or so. And then, I didn't get a recording one game. When I went to swap the batteries out, I noticed that the spring on one end of the battery holder was at an odd angle. At first, I thought that it had simply broken. But, a closer look showed that it was melted.

My suspicion was that in the couple of games where I got distracted and neglected to tape up the top of the aluminum tin, that enough sweat got in to short it out to the tin itself. I didn't see any scorch marks to confirm that idea. But, I figured I'd trying blocking that route and see what happens. So, took my conformal sealant and painted the inside of the tin. I clipped out the old battery holder and soldered in a new one.

But, less than 60 seconds after plugging the camera in and putting the helmet on, I felt heat against the top of my skull. When I opened it up, both spring ends of the holder were melted.

So, I have a short, somewhere. I'm not sure where it could be. I can't see damage to any component nor the circuit board. Possibly, there's a little discoloration where the black wire goes into the board. There is no corresponding mark on the tin in that area. Pictures here. I was wondering if anyone has any other ideas on where I might look.

I think I want to just start over, and this time put some effort into protecting the inside of the tin. And, also, change the connection to the USB connector that will reduce the size of the hole necessary, so I can seal everything better.

I wonder if the fact that I can't that I can't seal the actual connector might be an issue. I worried about sealant seeping inside the connector and blocking the connection I actually want. I've searched around a couple of times for a USB connector that isn't physically attached to the circuit board. But, my google-fu is apparently lacking. What I'd like is an inch or two of cable that runs from the circuit board to the connector. That would make for a much smaller hole. Does anyone know of such a beast?

Thanks,
Drake Christensen

MightyDrake
 
Posts: 5
Joined: Thu Dec 24, 2015 1:20 pm

Re: Melted battery holder

by adafruit_support_bill on Sun Oct 14, 2018 6:34 am

There are waterproof USB connectors. But they tend to be very bulky - as well as rather expensive.

But, since you really only get power and ground from the MintyBoost, you can use a waterproof DC power connector such as this one:
https://www.adafruit.com/product/743

You can splice a USB connector shell of the appropriate type to the camera end: https://www.adafruit.com/?q=connector%20shell

adafruit_support_bill
 
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Re: Melted battery holder

by MightyDrake on Sun Oct 14, 2018 6:51 am

Of course. That makes a lot of sense.

One other place I've been taping up is duck tape around the USB connector running from the extension to the camera. So, I think what I'll do is just cut my USB extension and solder those wires in place of the connector.

So simple. Jumps right out at me, now that you mentioned that.

Thanks

MightyDrake
 
Posts: 5
Joined: Thu Dec 24, 2015 1:20 pm

Please be positive and constructive with your questions and comments.