Solve the problem instead of putting a band-aid on it. Upgrade your alternator to something that can handle the draw of the winch, coupled with a good AGM battery and you won't have to worry about dual batteries.

95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes