Well, luckily for you energy storage happens to be my favorite hobby, I am like a magical pack rat (IMG:
style_emoticons/default/13.gif) . The first thing I would reccomend doing is becoming familiar with seals, atleast that is what I call them. They are alot like sigils, just set and forget enchantments that can be created to do anything. Most unrefined materials can hold a very limited amount of energy, what I mean by unrefined is that they have not been tempered by magics or enchantments.
Step one in creating an energy battery is to create a sigil, one made specifically to absorb and store energy inside something else, such as inside a rock, a stick, a person etc.. Do not be afraid to be too specific about what it will do and how, once you get the handle on making seals and sigils you will be able to trade them out at will, so if this one doesnt quite work right the first time, just make a new one.
Step two would be actually wrapping the seal/sigil around the object you want to store the energy. You dont have to do this physically, it can be done in your mind or with energy as easily as it can be done physically if not more so. What I recommend is to allow your subconscious to draw the sigil/seal onto the object with your energy, some seals become far to complicated to draw with conscious effort. The method I use is to sort of store the image in my mind, and when I wish to place it on something I raise my hand and see it fly out of my palm and wrap around the target, imbuing it with the power of the seal.
Step three is to imbue the object with energy, this time pour it in through the seal/sigil, you will find that it can hold many times its previous amounts, depending on what duty you gave to the enchantment (condenser,storage, or both).
The final step would be two fold, first "attach" the energy now stored inside the object, to the enchantment/seal/sigil, this will be the power source for the magic. It may sound stupid to say that you should use what you are storing to fuel the storage mechanism, but it is better than the problems an unpowered seal can produce (going caput and releasing all the stored energy at once). The second part is to attach the storage item to yourself, or yourself to it, so you can draw on the stored power even if you are very distant from it.
I hope this helps, this is my first post here, so be gentle if I seem ignorant XD