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Chestcold F 40 3 way fridge . 12 volt thermostat .
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<blockquote data-quote="Katabatic" data-source="post: 586721" data-attributes="member: 19153"><p>In theory, it's doable........in practice, not so much.</p><p></p><p>The switching contacts in a fridge/freezer thermostat are designed to switch around 1-2 Amps at 240V AC. There is a larger inrush current when the contacts first mate, but that's another story. The bulk of damage/wear incurred by contacts occurs when the current is broken (contacts open).</p><p></p><p>Your Chescold draws around 10 Amps from a 12V source....two problems....one, 10A is a hell of a lot more current than 1-2 Amps, and....even worse, you are switching DC and not AC. Switching high DC currents is a real bummer, which is why most small DC absorption fridges, like the Dometic range, don't even try it.</p><p></p><p>To successfully switch large DC currents (and have your contacts live to tell the story) requires a special magnetic arc extinguishing arrangement.</p><p></p><p>You can do it, and it will work (for a while)...but you'd better have a big box full of replacement thermostats handy <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>The only other option is a thermostat with solid-state switching......or you could try using the thermostat to operate a 12V relay with DC-rated contacts....make sure the relay is a plug-in type, 'cause you'll need to replace it too, but not as frequently.</p></blockquote><p></p>
[QUOTE="Katabatic, post: 586721, member: 19153"] In theory, it's doable........in practice, not so much. The switching contacts in a fridge/freezer thermostat are designed to switch around 1-2 Amps at 240V AC. There is a larger inrush current when the contacts first mate, but that's another story. The bulk of damage/wear incurred by contacts occurs when the current is broken (contacts open). Your Chescold draws around 10 Amps from a 12V source....two problems....one, 10A is a hell of a lot more current than 1-2 Amps, and....even worse, you are switching DC and not AC. Switching high DC currents is a real bummer, which is why most small DC absorption fridges, like the Dometic range, don't even try it. To successfully switch large DC currents (and have your contacts live to tell the story) requires a special magnetic arc extinguishing arrangement. You can do it, and it will work (for a while)...but you'd better have a big box full of replacement thermostats handy :) The only other option is a thermostat with solid-state switching......or you could try using the thermostat to operate a 12V relay with DC-rated contacts....make sure the relay is a plug-in type, 'cause you'll need to replace it too, but not as frequently. [/QUOTE]
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Outdoor & Recreation
Camping
Chestcold F 40 3 way fridge . 12 volt thermostat .
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