Battle Chests are special reward chests that appear after one of your battle victories. They can appear inside battle (victory) and outside (called Zone Chests). Either way, Zone Chests and Battle Chests contain any of these:
*Gold amounts vary: in normal chests without catching the Pet, you get 100; in normal chests when you catch the pet, you get no gold; Member chests usually contain 200 Gold; when catching, you get 100 Gold.
Very rarely, you can get food...usually, Apples are the food you get. Salads, Cake, and Chicken are much rarer.
You can get a wide range of items, most rare to find, in a Battle Chest. That way, you may get doubles of the same equipment and things. The Miscellaneous Items that have no use are much easier to find. In Zone Chests, there's always items inside, and usually, they are Member Chests and/or guarded by an obstacle or by a Cloaked Wizard.