Give your 2004.5-2005 Chevy/GMC 6.6L LLY Duramax a big boost in electrical power with new batteries. A battery's average lifespan is normally between three and six years. Chemical reactions cause batteries to steadily degrade even under perfect conditions. XDP carries the top brands such as Odyssey Battery, and more! Shop XDP and upgrade your batteries today! Dual batteries were offered on some heavy-duty diesel trucks. If your truck has two batteries, it's always a good idea to replace them both at the same time. Your truck's battery can fail and need to be replaced for a variety of reasons. The indications of a weak battery will often include slow engine cranking and dim or flickering headlights.