@gohan more safe. So what is the more part?? What happens if there is a problem and they got shorted. then there is a lot of energy released in a real short of time. batteries with a real low internal resistance are not suited for use where there are unguarded. Only if you really know what you are doing and knows that the batteries are of high quality. I worked at a company that made LiFePO4 batteries and battery monitor hardware. And i see the result of mishaps.