Waterproof Edelux lights?

Few bicycle headlights are actually waterproof. The Planet Bike headlight in our test wicked water past the headlight lens, and the standlight function stopped working. Busch & Müller’s lights are open at the bottom, so moisture can drain out. This means that you should not mount them in an area where they can be exposed to tire spray.
Schmidt’s Edelux headlights were designed to be waterproof, and for most customers, this claim has held true. In our group of friends, we have used Edelux lights in a Flèche that saw pouring rain for 20 hours straight. In PBP, I rode through 10 hours of thunderstorms with my lights on. None of us had problems with water getting into our lights.
However, a couple of customers report that water is getting into their lights, sometimes repeatedly, so we asked Andreas Oehler of Schmidt Maschinenbau about this. Here is his response:
“We had a few issues of Edelux being not 100% watertight with earlier production models. The water in these cases found its way inside through the internal sealing of the rear light connector. Current-production Edelux have an improved seal there.
“The most problematic situation is a headlamp mounted directly in the water spray from the front tire without a classic mudguard and without the plug of a rear lamp cable inserted. If this kind of use is planned with an older Edelux, we recommend to cover the rear light connector hole with a little piece of Duct tape. If a rear lamp connector is used, it should be isolated with heat shrink tubing and mounted with some bearing grease.
“Users should open the headlamp only as a last resort, because the front glass or the seal around it might get damaged. Noticeable amounts of water inside are a defect that is covered by our 5-year warranty.”
Here are some hints to get the most out of your Edelux (or other light):

• Mount it in a protected location.
• Underneath a handlebar bag is ideal, as it also is out of the spray being blown back from the tire at high speed.
• If you mount your light next to the wheel, use fenders with rolled edges, so no spray exits at the sides. (One case of multiple Edelux failures was on a bike with flat wooden fenders.)
• If you don’t use the taillight connector, you can cover it with a piece of tape. Or put a dab of grease into the recess.
• If you use the taillight connector, use heat shrink tubing on the wire, not just to insulate it against the light housing, but also to fill the recess. Then add a little grease to make sure no water pools in the recess.
• If your light needs to dry out on a tour (where sending it back under warranty is not an option), you can unscrew the lens. Before you do this, mark the top, so you don’t overtighten the lens retaining ring when you reassemble it. Make sure the seals and their mating surfaces do not get contaminated. However, disassembly is only a last resort, and should not be necessary.

For most users, the Edelux has been working flawlessly for many miles. Use the above guidelines to reduce the (already very small) risk of your Edelux suddenly going dark during a ride.