We often work with clients incorporating a winch on a vehicle. The winch manufacturer's specification includes recommendations of a battery, given they often aren't specific to brand or type of battery there are many considerations the owner needs to address. Here's a simple guide to help you through the process:
1. Purpose of the battery - in this instance the battery is needed to provide high current for a sustained period of time (much like a CCA rating over 30 seconds). The issue with CCA ratings is a high-quality battery like an Odyssey Battery will have a high CCA but will also be small Reserve Capacity or Amp Hour because it has a high power density and a small battery can output as much power as a larger wet cell or gel battery.
2. How often you use the winch - if it's occasional use then a similar-sized battery to your factory battery but with a higher performance spec might be all you need. You aren't reducing the Reserve Capacity and hopefully are increasing the battery's high power output.
3. If you run the winch for more than 30 seconds - you need to consider these as long duration discharges at high power, which means you are cycling the battery and therefore need to consider a deep cycle battery so you can repeatedly discharge and recharge. Remember though, a flooded deep cycle battery won't have a high CCA if the same physical size as your normal start battery. To compensate you'll need to increase the size of the deep cycle battery to get a higher CCA.
4. Vehicles charging system - Charging of the vehicles alternator would typically be fine but if you go off-road for the day and use your winch 5 or 6 times with a lot of low RPM driving and long duration winch pulls your battery will be quite flat once the surface voltage has dissipated. The alternator maintaining a voltage above 13 volts artificially leads you to believe the battery is fully charged. But if you leave it for 24 hours without using then check the voltage again you might find your voltage below 12 volts which is over 50% discharged. You'll need to use a maintenance charger after such days to keep the battery in good health.
That's a great basis for discussion and one many variables can be considered and put into play. Remembering the purpose of the battery is actually more important than it's spec sheet. 600CCA is great for instant power but not reserve capacity. Large capacity is great but not if there isn't a high power discharge available. Physical size may be important if under the bonnet of your vehicle. Large alternators only work if the battery has a low internal resistance to accept a large load current. All these reasons are why we recommend Odyssey Batteries with their extensive range.