I was looking for ways to charge my Android mobile phone and other devices whilst out on my bicycle, and began researching hub dynamos, bottle dynamos, and the selection of devices which could perform the relatively straightforward task of taking the AC current produced by dynamos and converting it to DC.
You can purchase the DC14 directly from Amazon for under
£25, £40: Nokia DC-14 Bike Charger Incl CR-124 Holder
As my research progressed, the prices involved for all the gear initially started to escalate. A complete hub dynamo wheel starts at a minimum of £80, and compatible bicycle USB charging devices such as the Reecharge costing another £65. That’s a lot of money to charge a battery.
However, my research also led me onto another discovery, the Nokia DC-14 Bicycle Charger. For £25 this kit contains a small bottle dynamo with mounting bracket, a charging device, and a handlebar phone holder. Pretty good value right? This kit is perfect, except for the fact that all that power is being sent to a 2mm Nokia plug. (Unless you have a Nokia of course, but then you’re limited to only being able to charge your phone)
So, in order to put this right it’s time to get busy with a pair of scissors, a soldering iron, some electrical tape and an old USB extension cable!
For anyone that’s is interested, this is the spec of the USB bicycle charger setup I’ll be making:
Charging starts at 3.5mph (6 kph) and maximum charging output is achieved at 15.5mph (25 kph). Charging stops when the speed reaches 31mph (50 kph).
Output is 5.0 V -450 mA at 9mph (15kph), similar to typical USB power. The maximum current is 700 mA (the same as your average mains charger), and this is reached at just 15.5 mph.
It was very simply really:
Step 1: Chop off the Nokia 2mm plug and discard, then expose the red and white wires at the end of the wire.
Step 2: Take an old USB extension cable and chop the female end off, then expose the red and black wires inside, ignoring the white and green data wires.
Step 3: Solder the wires on the Nokia cable and the female USB together, and tape the whole lot up. I’ve marked the positive and negative wires; Red (Positive) and White (Negative) on the Nokia cable, Red (Positive) & Black (Negative) on the USB cable. N.B. My USB cable had a white data cable, obviously you don’t want to solder that to the white Nokia cable! My donor USB extension was see through, so it was fairly obvious which was which…
Step 4: You’ve just successfully invalidated the warranty of the Nokia bicycle charger, but you’ve got yourself a female USB port which you can use to charge any* USB device right on your bicycle.
*Apple USB chargers are wired up differently (just to be awkward) so correct me if I’m wrong but this setup won’t work with your apple device, but then if you have an iPhone chances are you can afford to spend several hundred bucks on a fancy charger.
I’ve given this a quick test and it supplied a charge to my Android phone, and I’ll be giving it a full road test this weekend on a trip around the Llyn Peninsula. (Update 10th March: I’ve now fully tested this setup and it works exactly like it should! A bicycle mounted USB charger for £25, that’s good value in my book.)
Update 6th April:
A couple of people have requested additional photo’s of the setup, so here they are:
Disclaimer: Please note, if you try and copy this setup you do so at your own risk.