A Pricey High-Tech Battery Lets Us Down
In our latest round of car-battery tests, one model failed miserably: the Duralast Platinum with Absorbent Glass Mat (AGM) technology.
Battery makers tout AGM batteries as more capable of meeting the ever-hungrier electrical needs of modern cars—powering everything from infotainment systems to the fuel-saving engine stop-start feature. Our past tests have found AGM longevity claims to be generally true. The downside is that they can cost quite a bit more than conventional lead-acid batteries. The group size 48 Duralast Platinum AGM let us down. Not only did it trail other 48-sized AGMs but it also couldn’t even match the performance of less expensive conventional batteries of the same size. That was especially surprising because other Duralast batteries, sold at AutoZone, have earned CR Best Buy status in our Ratings. Our industry-standard battery-life test—which involves repeated charge and discharge cycles—proved the $165 Duralast AGM’s downfall. We require 15 weeks of good performance. One of our tested Duralast Platinum AGMs failed our life test at just five weeks. Another bit the dust after six weeks. To double-check, we bought a few more of the same AGM batteries, and one of those failed after three weeks. What’s more, our tests of Duralast AGM group 65 batteries had four units fail before 12 weeks. Buyer beware with this new battery.