You know, they never explained how the Autobots maintained their lifeblood. No mention of how or when they were able to replenish energon. Megatron and Starscrean even make it clear in the second movie that they were still looking for energon. So, i'm kind of wondering, were the Autobots basically starving since the first movie? It seems as though their own sparks are the only things keeping them alive.