Usually, when a battery "dies," or fails to accept a charge, it's due to one of two things. Either it's been allowed to run dry, which results in sulfation of the lead plates, or the battery has just been "beat up." How's that? Excessive heat is one of the worst enemies of battery life. Our research shows that battery temperatures in excess of 130 degrees Fahrenheit will dramatically reduce longevity. Usually, but not always, motorcycle manufacturers take this into account when positioning the battery in the bike. But you must understand the impact of heat should you decide to modify your bike in such a way that puts additional heat sources near the battery. Next on the hit list is vibration; besides heat, vibration is the most common battery killer. That's why it's important to inspect the battery's mounting hardware. A battery rattling around loose in the bike will have a much shorter life.