Originally Posted by
Abu Mahendra
...dynamo hubs make increasibg sense the longer you are off the grid. But even then, the power generated over a day's riding isn't enough to fully charge a cellphone with a 4,000mAH battery, much less a cellphone plus GoPro camera, lights, etc. Is the higher cost, increased wiring complexity, and mechanical drag justified?
It does depend on your electric needs. While riding, I have my GPS on, often have one AAA powered taillight on. Phone is off. Do not have a gopro camera. Dynohub and USB charger is enough to charge my GPS batteries, taillight batteries, one or two cameras (still photos only), headlamp (for head in campsite), and occasional phone use when I want to make a call or check a weather forecast.
My last two tours, never used a headlamp on my bike, as I avoid riding in the dark. See my notes below on bike headlamp and touring.
But if you are leaving a gopro and a phone turned on all day, I can see where your electric needs start to mount.
On a whim I bought a similar USB powered light with no battery, attaches to handlebar with an elastic, the one I bought was under $5 USD and has only one lens. It has three settings, high, low and flash (plus a fourth being off).
I found that when I plug it into my dynohub powered USB charger without pass through cache battery, that it would not light up until I was up to about 8 miles per hour, it started out on high setting. But after pushing the button to get it to low setting it stayed lit down to about 4 mph. Unfortunately, if I slowed or stopped and it went out, it would not light up again until I was up to about 8 mph. Thus it would be a poor choice for a light where I had stop lights, stop signs, steep hills etc.
Or the obvious solution is to power it on a power bank or to use a pass through cache battery with my dynohub. At the low setting, it consumes less power than my dynohub can put out so I could use it for extended periods of time on a bike.
My last two tours, I never used the bike headlamp. I have pretty much decided to just use the $5 light on my next tour if I need to go out at night or go through a tunnel, leaving my dedicated bike headlamp at home. Since any usage would be for short periods of time, I see this as a great solution.
But, if I was riding long audax rides, I would not want to rely on a $5 light as my only light source. I would have some form of backup, a backup that I would trust in rainy weather.