I recently read a discussion on my local gravel riding Facebook group regarding rear taillights. One of the super experienced local dudes, made a solid suggestion: go AAA battery powered. In my experience batteries are the way to go.
I have not had a positive experience with rechargeable bike lights. For headlights I have a Nightrider unit as well as a Sirius unit with a remote battery pack. Regardless of manufacturer’s claims my experience has been that if I keep the just light bright enough to light the Seattle darkness I’ll get, at most, three hours on a charge. I’ve had a number of bad experiences wherein I thought that the battery was charged but for one reason or another the power button goes red way too early. I traditionally bring along a battery powered headlamp that will allow me to limp home when my rechargeable headlight goes dark. But enough on headlights, this discussion is about taillights.
Four years ago I bought a cheap AAA powered taillight. I used it for a full winter before it was stollen. I never learned how to change the batteries in the thing as I never changed the batteries. I had spare batteries in my repair kit, but never used them, the thing simply kept lighting up – every time.
I replaced the cheap battery light with an expensive rechargeable model. The design was such that it was to beep when the power was low so that you could change it to a dimmer setting and extend the battery life. Within an hour the device would start emitting an ear-piercing alarm and then no matter how many times you pushed the button it kept beeping, every minute, until it died, which was rather soon. This year I went back to the sub twenty-dollar AAA light and despite dozens of hours in the dark I have yet to replace the batteries.
During these short gloomy days a functioning taillight is a life or death issue, and if you lose your rear illumination you ride should be over. I suggest that the best way to stay on the road during the dark months is to go with a replaceable battery powered taillight and to carry a spare set of batteries.
As a side note, despite the fact that my light is mounted on my seat post, I’ve observed that the most noticeable to traffic and least blinding to those following you taillight mounting location is on the left seat stay.