Most of the time there isn't a problem with cooking the battery unless you run for long periods of time at high RPM's, Amps and voltage drop quickly at lower RPMs.
Not that a regulator isn't a good idea, but sometimes they aren't available or are too pricy.
Turning on any electrical item can help too, depth finder, radio, a light, these will all lower the volts getting to the battery.
A larger battery can take more of charge too, so don't skimp on battery size.