Surya S Nair/Shutterstock An increasing number of electronic devices rely on built-in rechargeable batteries, but we haven't outgrown our need for single-use batteries. In the arena of alkalines, the two heavyweight contenders are Duracell and Energizer , but in a contest of lifespans , who reigns supreme? This question ultimately led to Duracell filing a lawsuit against Energizer, accusing its competitor of deceptive advertising. If you're looking for a data-backed answer, it's Energizer, but only with the brand's lithium Ultimate line. If we go by pure capacity, which is measured in milliampere-hours, Energizer wins by a mile, but only its top-of-the-line Energizer Ultimate brand. In comparison, the more affordable Energizer Max is almost neck-and-neck with Duracell, with Energizer holding a marginal advantage. If you were to compare the two, Energizer Max would probably only provide a minute or two of extra energy.…