Can a resistor be completely encased in hot glue?

[Forgotmyname]

Hello gentlemen,I am using a 1/2 watt metal oxide resistor to bypass a bad sensor on an outboard motor.I believe the currents around 200 milliamps so don't think it will generate a lot of heat.Would it be ok to just coat it with hot glue to keep it from the salt water environment or would it get to hot and maybe burnout or melt the glue?Not concerned if it gets a little warm just don't want to burn the boat down. Thanks for any help Melvin

 

[KMoffett]

What resistance? W=I(squared)R. Hot melt glue on a possibly hot resistor? How about epoxy?

Ken

 

[cowboybob]

Well, if the voltage across the resistor is 12VDC, Ohm's law states watts=E times I, so 0.2A x 12V=2.4 watts. Or ≈5 times the rating of your bypass resistor.

So, no, don't encase it in anything. Get a higher wattage rated resistor, say, 5 watts. That rating would allow the hot glue idea.

But, what ever you decide to do, rather than hot glue, I would be more inclined to encase the resistor in "Liquid Insulation":

with several coats. Better insulation and water proofing than hot glue.

 

[Forgotmyname]

I believe it's 5 volts so I should go up to a 1 watt resistor. Thats a great idea cowboy thanks for the tips I think I'll pick some of that up and give it a try.

 

[cowboybob]

Even a 5VDC, your 1W resistor is going to get rather warm. With the insulation, it will get warmer yet. Add to that the resistance will probably change (become lower) which will increase the current, making it even hotter... That's the usual trend.

And the altered resistance might affect its suitability as the sensor by-pass.

Anyway, it's your call, of course.

 

[tech master 117]

Ever tried connecting a 0.5 ohm resistor to a 9V fully charged battery.

 

[JonSea]

I would probably use adhesive-lined heatshrink tubing for this. The adhesive melts when heat is applied, them the tubing shinks sealing everything together. Handy material to have in a marine environment.