In my opinion it’s always best to use rechargeable power packs and carry spares. Once you start this process you’ll never look back. If a pack goes down then simply slid in your spare. You’ll soon get in the habit of recharging and having two sets of power packs available. But the big advantage of the power packs is their resistance to cold, where as standard batteries will start to deplete and fail in wintery conditions the power packs will take in their stride and reward you with reliability.