bishbosh Posted December 1, 2007 Share Posted December 1, 2007 I am preparing to install my rear winch in the RR. As the cable runs are about 15' I am concerned about voltage drop over the run. Should I be? I have searched t'internet but to be honest I don't really know what I am looking at. So the real question is, what cross sectional area of copper wire should I be using for a 12V winch with a max theoretical current draw of 350A. Come on, someone show me some formulae! Ta muchly! Quote Link to comment Share on other sites More sharing options...
Guest WALFY Posted December 1, 2007 Share Posted December 1, 2007 Bish When I ran the cabling to the rear winch I went for the biggest I could find at work. That happened to be 70mm2. No loss in power as far as I can see. Not that that hepls you much Quote Link to comment Share on other sites More sharing options...
bishbosh Posted December 1, 2007 Author Share Posted December 1, 2007 Cheers - but My battery is right at the front and the winch right at the back so my cable runs will be much longer than yours...... Quote Link to comment Share on other sites More sharing options...
Les Brock Posted December 1, 2007 Share Posted December 1, 2007 Bish....from another post I did Mmmmm.......I'm using 70mm' Tri rated this time....when I get round to fitting the winches that is ...although the cables are in already for them Current carrying capacity 25 mm - 183 Amps 35 mm - 226 Amps 50 mm - 274 Amps 70 mm - 351 Amps Roughly ..... for 90 oC Tri Rated cables degined to run hot volts drop for those interested.... 25 mm - 1.85 Mv/A/M 35 mm - 1.35 50 mm - 0.99 70 mm - 0.68 all these are Millivolts/per amp/per metre... so for example.... 70mm @ 0.68 Mv-A-M/ 300 Amps / 4 m cable run = 0.81 Volts drop 35 mm @ 1.35 Mv-A-M/ 300 Amp /4 m cable run = 1.62 Volts drop this would be higher if your current draw is higher obviously 35mm @ 1.35Mv-A-M / 450 Amp / 4m Cable run = 2.43 volts drop 70mm @ 0.68Mv-A-M / 450 Amp / 4m Cable = 1.22 Volts drop so your 12 volt winch with nominal 12 volts could only be getting 9.57 volts at the motor....using 35mm compared to 10.78 using 70 mm obviously you will have hopefully a bit more that the nominal 12 volts available but after a fair bit of winching you may not , and its only for comparison HTH Quote Link to comment Share on other sites More sharing options...
bishbosh Posted December 1, 2007 Author Share Posted December 1, 2007 Perfect Lesmond, thanks mate. Mods, can you please put Les' post in the tech archive as I couldn't find it in a general search.... Thanks. So. who has a good source of 70mm2 then....? Quote Link to comment Share on other sites More sharing options...
Old Spot Posted December 1, 2007 Share Posted December 1, 2007 Make sure the lugs are the correct size and crimped onto the cables using the correct pliers (cheap to hire from City Electrical Factors) other wise you will get massive voltage drop(and smoke ) at the cable ends. The correct size luggs are also cheap from the electrical wholesalers Quote Link to comment Share on other sites More sharing options...
Les Brock Posted December 1, 2007 Share Posted December 1, 2007 Bish, you know where I am if you want to borrow the proper crimpers...up to 250mm Quote Link to comment Share on other sites More sharing options...
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