Salt Water + 12VDC = ????

[james.e.raymond]

I am going to be testing some electronics submerged in SALT water. The electronics draw about 8 Amps from a 12 Volt DC power supply. I am testing the seals to make sure water does not leak. What will happen if a seal fails and the salt water reaches the electronic board? Will the salt water create a short and trip out the power supply? OR Will the water carry current and zapppp me if I put my hand in it?

Can I measure and monitor the conductivity of the water? If a seal fails and the salt water reaches the device board, will the conductivity go up enough for me to notice?

Any ideas or suggestions to make this safe or should I even worry about it?

[I_Daniel]

12 Volt DC cannot zap you. If you hold the + in one hand and the - in the other a few micro amps or even milli-amps may flow.

Salt water is conductive. The saltier the more conductive. You could possibly insert probes into the water and use a high input impedance electronic meter to measure the resistance of the salt water. It could be a low to very high (20M Ohms or even higher ) Depending on the size of the holder and how salty the water is. (Remember to wash the probes immediately with clean water)

If the seals break or leak then the salt water will cause shorts all over the board.

Salt water is corrosive so the Printed circuit board could also be damaged. But if it is washed off immediately then it should still be okay.

If you have an ammeter connected "full time" then there will be an increase in the current that is drawn if the seals fail. If something blows then the current draw could also increase or decrease.

If the seals fail then the device could be permanently damaged due to the shorts all over the PC board/Components.

Incidentally --- Some micro electrical therapy systems use this supply voltage which in many cases the battery get connected as is using electrodes on the arms or across a cut or tissue damage. It started off with fractures and then expanded into other fields All they do is put a variable resistor and a micro/milli-amp meter in circuit and reverse the electrodes anything from 10 minutes to an hour, for a maximum of two hours per day.

Remember it is not how many amp hours the battery is capable off it is the resistance of the circuit that limits the current. But the higher the EMF (voltage) the higher the current flow through any given resistance. (Ohms Law)