The Magic Shine MJ-872 never gave me any trouble in the rain. It uses a sealed, external, rechargeable battery pack. 1800 lumens I believe, but it's a trail light so it has a very wide beam and no blink/pulse mode.


I just replaced that, however, with a Cygolite Expillion 850. It's USB rechargeable, has a removable, internal battery, and a few different pulse modes. Great coverage and beam pattern, plenty of bright enough for my semi-lit night commute, and so far no troubles in wet weather.


I'm not sure exactly what your definition of a big honking log is, but if you want something that's effective beyond 25 feet - especially in the rain - then you might consider stepping your game up a little.