On a related note, is there any reason not to leave a winch permanently hooked up to a battery? Is there any potential for damage to either the winch or the battery? My battery has 4 posts, so 2 can be used for the winch.
I usually disconnect for highway driving - I don't want a 1/0 cable live/hot in case of a front-end collision.
A live 1/0 cable without any means of circuit control is kinda spooky, there is a whole wack of energy just waiting to run amok. If everything stays happy and Murphys stays away, all will be well. BUT, it could also burn your truck to the ground before you can get things under control. My favourite solution is a dedicated underhood switch on the main power cable to control pack. Something along the lines of this,
Amazon product ASIN B0130WZON2
Take careful note of the continuous amperage rating of any switch you may be considering. Compare this to the maximum your winch is capable of drawing. I've seen alot of this particular model of switch on heavy trucks, seem to be a nice beefy unit, big posts for connections. Haven't yet seen one fail, and that includes alot of hard starts at very cold temperatures. Check the specs carefully for your application. Would be a bad place to cheap out I'd think.
Even the one posted above, despite its size, is rated for 250 amps continuous, although 2500 amps short duration. I believe these to be conservative numbers based on the size of the unit.
A quick google search shows a 12v Warn M8000 drawing up to 435 amps at full load.
Peak amperage for how long? Probably not very. Will it be a problem? I don't believe so. A friend of mine runs the exact model of switch shown above on an 80 on 37's with a 12k Warn, so far so good.
Thats a whole lot of hot air to say I like to put a big ol switch on the circuit, just needs to be sized accordingly. Also, having the switch underhood makes it tougher for any shady characters to get up to no good with your winch. I have only heard tales of this, thankfully.
Probably alot more winches wired direct than otherwise, but that doesn't mean there isn't a better way.
Fun fact, my HDJ81 has the OEM electric winch, it uses a big ol solenoid to isolate the battery side of cable until you plug in the winch controller.