Origins & History
The Orange Power Battery was created by Geoff Johns and first seen in Green Lantern #39. Larfleeze discusses its origin in issue Green Lantern #41.
For unknown billions of years, the Orange Power Battery existed dormant on the planet Okaara in the Vegan system. The only person who knew of its existence was the Maltusian Krona who drew a map to its location. This map was part of a group of artifacts that was stolen from Maltus by a small guild of thieves - amongst these thieves was Larfleeze.
The Guardians of the Universe sent their Manhunter robots in pursuit of the thieves. During their escape, they discovered the map which led them to Okaara. There they discovered a temple which they found held the Orange Power Battery. Feeling its power, later admitted by Geoff Johns to be the emotional embodiment of avarice, speak to them, the thieves began to fight over the battery.
The Guardians and Manhunters located the thieves and conflict ensued. The Guardians feared the power of the orange light and offered the surviving guild members - Larfleeze and Blooch - a deal: in exchange for the box and their freedom, the Guardians would allow the orange light to remain in their possession. First, the Guardians would not enter the Vegan system. Secondly, they would allow one thief to wield the light. Both thieves agreed and fought to the death for the orange light. Larfleeze was victorious and became Agent Orange-- The Only Current Living Orange Lantern, Except for Lex Luthor, and Hal Jordan, who both wielded the orange light of Avarice between the beginning and the end of the Blackest Night. During Brightest Day, Hector Hammond stole and consumed the battery. Larfleeze still retained ring power, but with no way to recharge, we was worried. During War of the Green Lanterns, when the New Guardians were exploring Ryut, they stumbled upon the Book of the Black. The book spit out the orange lantern, which Larfleeze ran to grab. Using it as a trap, Lyssa Drak used the book to first absorb Larfleeze then every other lantern present minus Hal.
Powers, abilities, and skills
Effectively, the Orange Power Battery functions similarly to other Corps Central Power Battery. Unlike the others, the orange battery is small enough to be held by Larfleeze - who holds it close to him at all times.
The power battery empowers Larfleeze's orange power ring constantly. The battery has been shown to charge his ring to 100,000 percent power - for comparison's sake every other Corps can only reach 100% or 200% if a Blue Lantern wishes for their well being. It also has the ability to "Recruit" other members, such as in The Story of the "Hunger God" Blume, who had his identity stolen and was killed by the Power Battery when he demanded Larfleeze to give him an offering.
Since Larfleeze has been exposed to the battery for billions of years, he claims that it is as much a part of him as the Green Lantern Central Power Battery is a part of the Guardians. This is proven true as he isn't de-powered when Hal Jordan briefly steals the battery. Also, he retains the ability to use his ring after Hector Hammond steals and swallows it.
As stated above, and confirmed by Geoff Johns, Ophidian, the entity of avarice, resides within the power battery.