Waterproofing charger cable?

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kenkeniff

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#162137 30-Jan-2015 12:13

Say I have a small electronic device like a mobile phone which is charged via USB cable;

If I left the USB cable permanently attached to the device, what would be involved in making the USB Male end of the cable waterproof (not physically but electronically) so what I would submerge the end of the cable in an electrolyte or even bridge the terminals and it would have no effect on the device.

Is there a standard schematic for this type of short-circuit protection (like you see with a number of waterproof devices with exposed gold-plated charging terminals)?

timmmay

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#1225276 30-Jan-2015 12:34

Can you give more background about what you're trying to achieve? Sounds bizarre.

Niel

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#1225693 30-Jan-2015 22:18

No, trust me, I design IP67 rated electronic products. The contacts will die. You will not damage the phone, it is purely an electrochemical connector/cable problem. USB devices have to pull one of the data lines high through a resistor for signalling its presence to the host, so you will get corrosion. Furthermore, overmould cables are not bad for water ingress but it still will get water wick up the cable and change the characteristic impedance which screws up the high speed data signals. And the copper will turn green/black. And the insulation material absorbs moisture (over a long term).

Even the IP67 rated USB connectors are only IP67 rated when the connectors are mated, or the dust cap is screwed on. You will need to use one of those cables with a cap (when unplugged), and then (often) have trouble plugging it into a normal USB socket as it usually have a shroud for the thread. Google IP67 USB for images of the cables I'm talking about.

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richms

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#1225733 31-Jan-2015 02:12

If its just charging, you could get some of the wireless charging backs for phones and stick it inside the product, and then put it on a wireless charging base lined up to get it to charge. If its for data as well then re-visit how things work. there are plenty of cheap low speed serial over wireless techniques if that is all you need, if its more bulk transfer then wifi isnt that expensive in module form now

Richard rich.ms

Niel

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#1225740 31-Jan-2015 07:39

Can you give more info? Also, what batteries are you using as e.g. NiMH cannot be sealed in a case. We have seen what happens when the minute amount of hydrogen gas that's released during charging got ignited by ESD. Waterproofing is not straight forward, need more info if there is any remote possibility of (reliably) doing what you described in the OP. Many waterproof products are not, they are water resistant.

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