That's a very clean and nicely designed setup. However, your main battery cable doesn't look any where near sufficient for 300 amps, let alone 400.
Back at ya! Sincerely appreciate the sentiment and consideration!
It's all about time and distance which directly correlates to total cable resistance, which drives the heat problem. You are correct, for a sustained 400A draw at 10ft, no way would I pick those cables. My winch may occasionally hit 370 Amps for a few minutes....maybe. if it hits 400, then there is definitely a problem, therefore the fuse. The cable you see going into the bottom left fuse is the cable wired to the winch by the winch manufacturer. Same for the next one to the right, the premier power welder. Full disclosure, the large bus bars are rated for 400 Amps, so I can't weld and use my winch. I think I am safe there. The 8inch jumper from the bus bar to the battery positive terminal is part of the excess cable removed from the winch. Those cables were shortened by 18", so safer still. If you think my cables are small, take a look at your positive lead attached to the 240A stock alternator(or generator in Ford speak), that will make you say hmmmm.
So do you think you winch manufacturer chose wisely (or even safely)? The ABYC table for in engine compartment cable with a very good jacket (rated to 257 deg F), rates a 000 AWG at just under 375 A (365). Sure, this is continuous usage, but I would call the duty cycle of a winch continuous.
I dunno if I’d go that far.
Just curious, what is the length of cable that rating is based on? Allowable voltage drop is also another consideration. Continuous really means continuous at an ambient temperature of 257F with enough cooling to maintain 257F and preventing thermal runaway. With those requirements, I am surprised 000 AWG is big enough, but then again it depends on acceptable voltage drop, type of insulation, solid core, stranded core... If 20% drop is acceptable with an 18" run at 200F, you can get down below 2.5 mm2 or 1 AWG. But then again it depends what calculator you use. Charts only get you so far, calculations based on IEEE standards, no wait ASTM...or was that SAE, oh yeah, you chose the ABYC...or just use good engineering practices, build a prototype for your particular use case, build a solid validation testing program and then perform a thermal analysis under max expected load plus 20% with a safety factor of 2....nope, absolutely not...run it and if you can grab the cable after, cable good. If not, go bigger or limit duty cycle...just trying to have fun. And right now there is someone out there saying my solution is over engineered...I know you're out there, admit it... (this is all in good fun) thanks for the feedback! (There are two mistakes up in all I said, can you find them?)
At the speed of a winch I would call a 50' or 100' continuous for practical purposes. No it certainly is not literally continuous.
Good points largely agree. That said you still didn't answer the question... Do you think the winch manufacturer chose wisely?Just curious, what is the length of cable that rating is based on? Allowable voltage drop is also another consideration. Continuous really means continuous at an ambient temperature of 257F with enough cooling to maintain 257F and preventing thermal runaway. With those requirements, I am surprised 000 AWG is big enough, but then again it depends on acceptable voltage drop, type of insulation, solid core, stranded core... If 20% drop is acceptable with an 18" run at 200F, you can get down below 2.5 mm2 or 1 AWG. But then again it depends what calculator you use. Charts only get you so far, calculations based on IEEE standards, no wait ASTM...or was that SAE, oh yeah, you chose the ABYC...or just use good engineering practices, build a prototype for your particular use case, build a solid validation testing program and then perform a thermal analysis under max expected load plus 20% with a safety factor of 2....nope, absolutely not...run it and if you can grab the cable after, cable good. If not, go bigger or limit duty cycle...just trying to have fun. And right now there is someone out there saying my solution is over engineered...I know you're out there, admit it... (this is all in good fun) thanks for the feedback! (There are two mistakes up in all I said, can you find them?)
Not really sure. I think it's all in how you design the worst case use case and then examine the trade space. For example, how long will the winch be operated at max output worse case, balanced against how long a given cable size wll take to reach thermal runaway and then add in a safey factor. Then you can add in how long the winch motor will survive a fully stalled state. since I have yet to see a winch with a fuse, or breaker that must be installed when the cables are hooked up to the power source, I am pretty sure there is a thermal cutout in the controller, which most likely resets after everything cools down. the winch motor and controller become the limiting case and the cable choice becomes pretty simple and most likely why they seem undersized. They will never see enough loading to cause failure before the controller protects everything. That is my guess anyway.
