Modifying My Boat's Keypad Module: Searching for a Heater Pad

[anorlunda]

The chartplotter on my boat works fine. But the buttons work via a sealed keypad module. The contacts use (I think) a. Conductive grease. It works fine when the temperatures are 70F (20C) or higher, but not fine when it is colder. I'm fond of that device. I would rather modify it than replace it.

I'm looking for a 12v heater pad, no bigger than 1" x 2" x 1/16" that I could add. I think 10 watts would be plenty. I would wire the pad in with a momentary switch, and use it for short period only.

Can anyone suggest a good candidate? Motorcycle hand grip heaters seem almost ideal, but at 3x3 inches, they are too big, and I don't think I could trim them to size.

 

[billy_joule]

You can make your own. Electronics stores have nichrome wire.
Google "DIY Heated bed" there's a wealth of information as they're used for diy 3D printing, here's one tutorial:
http://airtripper.com/698/resistance-wire-heated-build-platform-diy-tutorial/

I would power it off the acc feed and use a thermistor and simple circuit to have the heater turn on below X degrees. Install and forget. I would think 10 watts would be overkill, one or two would do.

 

[Mike_In_Plano]

Try Watlow. They sell strip heaters made in Kapton and silicon rubber of various sizes and shapes. For your application, It's difficult to say what a good wattage would be. For a roughly 13V system, 169 Ohms would give you 1 watt, 85 Ohms, 2 watts.

Mike