You will need to calculate the vehicles power requirements, the battery size, then fit a larger alternator to cope with the vehicles demand, and that of an alternative battery.

I am currently writing an article on this very subject to be posted here in the near future.

If you intend fitting an electric winch it is always prudent to fit an additional battery, if possible use one of the latest electronic split charging systems. These systems are often programmable, and will ensure your vehicle battery stays charged, irrespective of the state of the auxiliary battery.

You will need the specifications for the winch, this will have a recommended "cold cranking amps" minimum, or CCA range. Select an auxiliary battery within the range, or above the minimum CCA requirement for the winch, forget many of the big expensive names in the aftermarket sector. Most of these are for the image conscious, i prefer Exide batteries, just as good as Optima or other well known brands, but about a third cheaper and do the same job.

When fitting the winch:

Ensure it is securely mounted to the chassis on the heaviest plate possible, place the battery as close to the winch as practical, and ensure the battery leads are heavier than required.

Fit an appropriately rated isolator switch into the circuit so it can be isolated to work on the winch, or switched off if damage occurs.

I would recommend attending a winching course, these are great devices if used properly, but can be deadly (fatal) if incorrectly used. Most people assume they can use them, but most cannot, the cost of such a course is peanuts compared to what a novice may learn, and it will often save your winch and prolong its life.