Interesting seeing peoples views. I like the number of times the word bright appears - IMO much more important than the flashing or steady issue.
I've had this a couple of times and its really annoying! Why do the manufacturers of bike lights get away with producing lights that fail when thy get wet? Its not that hard to make something water resistant and this should be a basic requirement for lights!
The only bike lights I have which are really waterproof are the dynamo ones, which don't have to come apart. Battery ones have to open up, and the seals don't work properly after a few uses.
Buy some clear silicone grease of the sort intended for electronic and electrical use (CPC do some) and smear it very sparingly on the outside of the joint after you change the batteries. I've been doing that for decades, and don't have any problems, even with lamp types known for their water issues.
Keep the grease out of the joint itself as it can make the lights come apart too easily.
It isn't just bike lights, it's anything with batteries in it that's made down to a price and not up to a specification!
) . I've already got a headstrap inspection light from Tesco last year - very bright it is too - which I use at home (minus helmet) to check the bike tyres in Winter before putting the bike away in the shed. It's incredibly useful - but it just won't go on the helmet.
