It doesn't reduce the voltage when the temp increases which is needed to not overcharge but some people esp w high draws as said have used it w no (reported) probs to the batt but over time it sure could shorten it's life but it'd be hard to pin it down to that (the blue reg) if the batt only lasted 3 years instead of 5 like the last batt (of the same type) as quality control is always a prob (& always suspect) EDIT best to feed hi amp items from the alt side (w relays) w a medium sized batt on the other side