Ahh, that is good to know. Hmm.

I don't know if that's normal. Most of my training has been early morning in the dark with those battery powered lights so they get used almost every day rain or shine, and my training bikes don't have fenders. I think it's the water and vibration that eventually kills them. I have the same issue with every headset I've tried except for CK. The Ixon lights aren't all that expensive in the grand scheme of randonneuring expenses, especially compared to dynamo lighting, so I just bought a few spares.

Another tip is to get a bunch of eneloop rechargeables and a smart charger.

I have the Ixon IQ Premium (the battery powered one), and i used it for a long time (it is now unused in a shelf due to the fact that i have more expensive much better lightning toys now, but i am still happy with my (dyno powered) Cyo Premium for city use, which has the same reflector and LED and identical output)
At this time of writing, the beam shape is still nice, but it is woefully underpowered. Also the 80 lux is only available on a small area, the rest of the beam is notabely darker. It is still sufficient though in case of dry, totally unlit roads, if there is no oncoming traffic. Then your eyes can easily adapt to the low light output and you have a nice beam shape. The definitive advantage of that light is: you can really easy swap the AA cells on the road. Here is a nice video of the IQ Premium: youtu.be/WwM7vDvvGhU
The mentioned SON Edelux II uses the same reflector as the IQ Premium, albeit a better LED binning and has better cooling, so runs on a bit higher power.

A newer dyno light like the B&M IQ-X beats the IQ Premium easily, those 100 lx are spread out much wider than the 80 lux from the IQ Premium. On Lux Values see here

Probably B&M never intended them to use with the fork mount with out mudgards/fenders. so i'd say kingstons observations are not representative :).
I agree to get proper eneloop rechargeables to avoid high self discharge of standard NiMH cells.

I guess lighting is a very personal thing. I have ridden a lot of miles at night in the rain with the 30 lux Pure and find that to be totally adequate. I've also ridden all night in the rain with the Ixon IQ on low (15 lux) and thought that was just fine too.

I think under normal conditions, it doesn't take much light to be just fine. Descents under less than perfect conditions are the exception. That, and urban potholes. Unlit country lanes don't require much light at all in my experience.

I used to use Eneloops and there is nothing wrong with them, but I have since bought some white Ikea Ladda NiMH AA and AAA batteries. They work very well for me, a bit more capacity than the Eneloops. Now I only buy them.

The only disadvantage is that there are not that many Ikea stores, so hard to find unless you pay exhorbitant fee for shipping.
https://www.ikea.com/us/en/p/ladda-r...tery-70303876/
https://www.ikea.com/us/en/p/ladda-r...tery-90303880/

I specified the white ones because they used to sell some cheaper ones that were not low discharge, but the ones I do not recommend do not show up on a search anymore.

I use a couple different smart chargers.

Hi,
On one bike. I run a Edelux front, B&M Secula Plus Rear powered by a Shimano dyno hub DH-3n70. On another I run an Edelux front, Rene Herse rear (threaded into the seat tube) with a SON 28 hub.
Both are reliable and consistent, and as a back up taillight I run the PDW FenderBot. Front back up is any USB rechargeable.
I commute and ride in the rain, and find the beam shape and brightness perfect.
With the Edelux, I run the light in "on" mode, for daytime visibility in the city.
Longer range, carry a 10k Mh battery pack to recharge or a wire and plug. same as you'd use for your phone.
Also, the USB e-werk adaptors offer trickle charging off the hub, but check that the power required won't effect the lighting.