The Sinewave Cycles Revolution is a bicycle dynamo powered USB charger. It converts electricity generated by hub and bottle dynamos to USB output. The Revolution allows users to charge USB-powered devices while riding. The Revolution provides an easy to access USB port that you can attach to your frame and then route to a device. SPECIFICATIONS: Starts charging at 3.5 MPH (5.5 km/h) Full charging at 9 MPH (14.4km/h) Max current: 1 Amp Also works with DC input up to 52V Weight: 37 grams Dimensions: 54mm x 35mm x 14mm Wire length: 36″ (91 cm) Wire ends: Stripped wire The chargers do not have a cache battery. We are occasionally asked about that, so we wrote an overview of our thoughts on batteries in our FAQ. Here's what is says: Does the Revolution have a built-in battery?
- No – and this is a good thing. Most chargers that include a “cache battery” do so because they are not efficient enough to directly charge a phone – they must slowly charge a battery, then charge the phone from the battery. This adds further inefficiency to the system, as well as a delay while the internal battery is charged. The Revolution is able to directly charge your phone, making the cache battery unnecessary.
- Some chargers have a larger built-in battery, meant to store a large amount of energy. There are several reasons we don't like this system:
- Product lifetime. Batteries wear out. Even the highest quality lithium ion battery is rated for about 3 years from manufacturing, independent of how much you use it. There's nothing in the Revolution that wears out. When you build up a touring bike you select parts based on reliability and durability first, and everything else second. We want the Revolution to be the same way.
- Efficiency. The extra steps to charge the battery, then use the battery to power the output is a significant hit on efficiency. Most users directly charge their phone, and the extra conversion steps mean wasted energy.
- Flexibility. A product with an internal battery is stuck with that one battery, which may be too small for some users and too large for others. There are many USB battery packs available in all sorts of shapes and sizes and capacities. The freedom to use a battery that fits your bike and your tour is lost when an internal battery is used. This also allows the Revolution to be as small as possible.
The low speed performance depends mostly on your device, and the minimum current that it is willing to accept. We get to the USB standard 500mA around 9MPH, so just about any USB device should be able to charge at that speed, and most of them continue charging at lower speeds – for example, I toured last summer with my Android phone and it kept charging down to about 5.5MPH. If you do find yourself riding very slowly (lots of climbing or off-road riding, for example) or are trying to charge a high power device (like an iPad), we recommend using an external USB battery. You can use those in two ways – you can charge the pack during the day and then charge your device at night, or you can use the battery as a buffer so that the battery charges your device while you ride, while you charge the battery from the Revolution or Reactor. There are no devices that are not recommended, and we've found that we work just fine with iPhones, Samsung Galaxy phones, etc. The only limitation seems to be whether or not the dynamo itself is generating enough power to keep your device happy – for most situations it is, and in the other cases you can simply use the external battery solution.