Originally Posted by
cyccommute
They make a lot of sense for someone who rides every day as well. With a $20 light, what does it matter if the battery shorts out? By another light and it comes with a battery. It also makes sense from the standpoint of having more than one light source. Not just for back up but also for utility. Multiple light sources make you stand out more and, at $20 per light, having two or three lights (a light on the helmet is extremely useful) doesn't break the bank.
Well I don't use them everyday so I can't comment on the longevity of the battery packs, I will say this though, You have to be careful mix and matching battery packs now, I have two $20 sets I've been using for a few years and recently bought a third, that looked identical in every respect, but the battery was double the voltage, 8-volts. Without a thought I hooked it up to a 4-volt light and blew it. A silly mistake, I should have checked the fine print. Here is the unit, though I won mine at auction for only $12 delivered
Waterproof 5000LM Cree XM L T6 LED Headlamp Head Front Bicycle Lamp Bike Light | eBay