One Trick Pony by Nathan Hale
The aliens have arrived. And they're hungry for electricity. In the Earth of the future, humans are on the run from an alien force-giant blobs who suck up electrical devices wherever they can find them. Strata and her family are part of a caravan of digital rescuers, hoping to keep the memory of civilization alive by saving electronics wherever they can. Many humans have reverted to a pre-electrical age, and others have taken advantage of the invasion to become dangerous bandits and outlaws. When Strata and her brother are separated from the caravan, they must rely on a particularly beautiful and rare robot pony to escape the outlaws and aliens-and defeat the invaders once and for all.