blackwolf
Member Since: 03 Nov 2009
Location: South West England
Posts: 17756
 
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FWIW I would never use anything less than 35mm2 for a winch (at least not for a winch of a size suitable for a Landrover). I always tend to over-spec the cable, because I want all the available power at the winch and to avoid power losses in the cable.
There will always be some voltage drop over the length of a cable, the amount will depend on the overall impedance (resistance) of the cable, and the current being drawn by the winch. The max current draw will be when the winch is stalled, and is largely outside our control. The overall impedance of the cable is a product of its length (over which we have no control), its construction (which we can control by choosing a quality cable) and its CSA (cross sectional area) which is the biggest single factor. So by buying a thicker cable of good quality we can ensure that more power is available to the winch.
The other factors are:-
Flexibility - it may be necessary to make fairly small radius bends to route the cable, and we may need a flexible cable to get it in place. Also, a flexible cable is less likely to abrade on points of contact along its route. A flexible cable is therefore good.
Heat - any cable in prolonged use will warm up, the amount it heats up is again a product of impedance and current. Since we can't readily alter the max current that can flow (winch stall again) we need to minimise the impedance by using a large CSA cable. The cable may still get hot, and therefore the insulation needs to be sufficient to withstand any heat generated. In practice, if the cable is of adequate size the majority of electric winches will overheat long before the cable. If the cable is of inadequate size, however, it is quite possible to melt the insulation and get a direct short to ground. This is bad, since your truck will then catch fire and be destroyed.
Abrasion resitance - the underneath of a 4x4 is a hostile environment and any cable needs to be sufficiently rugged to withstand it. A flexible cable is usually less susceptible to abrasion than a rigid cable, but any cable must be adequately supported and secured, and routed to avoid sharp edges etc. Cable protection can be enhanced by running the cable inside a flexible conduit (like those used by LR for wiring harnesses) but remember that this can effect the heat build-up in the cable.
Accident survivability - be mindful of the fact that if you are involved in a serious accident you absolutely do not want your winch's electrical supply providing a dead short to ground. You truck may be damaged already, but you do not want it to combust spontaneously before you have been able to get yourself and your loved ones out of the wreckage. For that reason there should not only be an isolator switch but it should be as near the battery as possible, so that the winch supply cable is not live all the time. This is particularly important since the winch tends to be at the extreme front of the vehicle and is therefore susceptible to collision damage.
I have installed winches on all my LRs over the years, and my approach is always the same:-
1) use high-flex double insulated arc welding cable of at least 50mm2 CSA
2) fit an isolating switch as near the battery as possible so that it protects both the winch and the cable
3) run the live feed to the winch in a flexible conduit for added protection
4) run a dedicated earth from the winch to the battery using the same size cable.
5) make all connection with proper tinned copper crimp terminals of the right size crimped with the correct tool (Snap-On/Blue-Point make an excellent universal crimp tool which is very affordable, as unlikely as that may sound) and use adhesive hear shrink sleeving over the crimp to insulate and reinforce.
6) fit protective covers over all non-earth connections.
I always tend to use Superwinch Huskys since in my opinion they are the best light 4x4 winch available for serious (non-competitive) winching, and I never see any point in spending perhaps £2k on a winch and then skimping perhaps £50 on the installation. Using the above approach may be overkill, buyt I have never once - at least not yet - had any problems whatsoever with a winch installed in this way.
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31st Mar 2011 3:41pm
