Winch shutoff and electrical question

[cyked]

For a 12k winch (smitty x20 gen 3) which switch should be used (275 amp vs 600)?


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[BasementKitty]

At stall that thing can draw greater than 400amp. Go bigger. It will reduce voltage drop at high current loads.

 

[cyked]

What's different between the two? The larger has 1/2 studs and the smaller one has 3/8. I assume there's nothing fancy here, it's literally a metal switch used to open/close the circuit. I would have to cut and replace the 3/8 terminal connector on the winch pos battery cable with 1/2, and also seems like 99% of bigbox retail only sell 3/8 2 awg and not half 1/2 (though I did find batterycablesusa to order custom cable/lengths in any size and config).

 

[LazyJL]

The 600-amp switch will have bigger internal contacts to handle the higher amperage. It's best to never run a switch at its full rating.

 

[cyked]

If the switch contacts are bigger, then won't the winch wiring, battery terminal connectors, and the rest of the wiring being smaller just be a new weak point? I feel like this is just moving "the issue" around, especially when there are a lot of people who just wire directly to the battery and be done with it.

 

[BasementKitty]

Voltage drop occurs according to Ohm's Law, so it's not so much about a "weak point" which would be valid if we were talking about the rest of the wiring acting like a fuse. Instead, resistance is cumulative, so anywhere you can reduce resistance will improve current flow which in turn reduces total voltage drop which in turn improves performance of the winch both in the amount it will pull as well as how hot it gets. At low current draws this is negligible. At high current flows this becomes significant.

Further, places like an undersized switch will often concentrate heat due to increased resistance when there is sustained high current flow and becomes a failure point. .001 ohms resistace in 10 feet of wire has the heat dissipated throughout that entire length of wire. A dirty or loose connection can cause high resistance in a small area which means all of the heat is concentrated right there.

Regardless of that though, like you, I direct wire my winches to the battery.

 

[VKSheridan]

The highest amperage your winch will ever see is whatever your battery can produce. If your battery can push over 500 amps, the relay can potentially see over 500 amps. Adding a 600 amp relay to a maximum 400 amp circuit adds no value. The battery can only deliver what’s it’s rated at. The best reason to add a power isolation relay is in the off chance one of your winch directional relays weld shut. Most winches have an internal breaker should it draw more than it can handle so the role of the PIR becomes eliminating parasitic draw.

 

[davewald]

I use the 455 amp versions on my 10K Warn winch and a separate one on my ARB twin compressor. It has never given me a problem or gotten too warm, and I've used both to the max many times.

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