Funding Canceled Funding for this project was canceled by the project creator on August 13, 2013.

A stylish, high-capacity portable USB battery pack that can be powered from a bicycle dynamo or a standard wall adapter.

Why PowerCycle is Awesome:

  • Flexible power source: It can be charged from a bicycle dynamo, 5V solar cell, USB port, or tablet/smartphone wall adapter. Use it where you want, when you want, on-grid or off.
  • Powerful and fast: With a 1.9A power output it can power tablets and other power-hungry electronics and charge devices up to four times faster than the competition!
  • Holds its charge longer: Other battery packs have an annoying habit of quickly losing their charge when not being used. PowerCycle is designed to take well over a year (500 days) to fully drain, so it’s ready to use when you need it!
  • User upgradeable and built to last: Every other USB battery pack on the market is a disposable product! Lithium-Ion battery cells have a limited lifetime of about 300-800 charges, or about 2 years of regular use. PowerCycle has user-replaceable batteries and power circuitry making it better for the user & the environment!
  • Not YAPP (Yet another piece of plastic): PowerCycle's shell is made of anodized aluminum and built to last. Made locally in the USA!

The Full Story:

PowerCycle is a high-quality USB battery pack designed to power your day. Smart and efficient power electronics, superior construction and top-brand battery cells put PowerCycle into a class of its own. Unique in a battery pack of its price, PowerCycle can be powered from any bicycle dynamo (not included). Whether you charge it from a standard USB port, wall adapter, or attach it to your bicycle dynamo to convert and store power as you pedal, PowerCycle provides a portable, flexible source of energy. It easily attaches to a bike frame or can be slid into a pocket or purse on the way out the door. Its high-current output and intelligent charging circuitry allow it to quickly charge practically any existing USB device, from LED bike lights to the latest tablets.

MkIV prototype with 3D printed plastic case (final case will be anodized aluminum)
MkIV prototype with 3D printed plastic case (final case will be anodized aluminum)

Using PowerCycle is as simple as plugging in the device you want to charge. The intelligent charging circuitry will automatically optimize its output to your device's charging capabilities and the light ring around the USB port will begin to glow indicating that charging has begun. If your device supports fast charging, as many of the latest smartphones and tablets do, PowerCycle can charge it in about half the time of a standard USB charger. As the internal battery on PowerCycle runs low, the light ring will shift from green to red, finally blinking to warn the user before charging stops.

An elegant anodized aluminum body available in a selection of colors protects a modular and user-replaceable power system. A rugged barrel connection on the power input ensures a reliable and vibration tolerant connection to the bicycle dynamo. PowerCycle can be opened with a standard 2.5mm Allen key, allowing the circuit board and batteries to slide out for repair or replacement. Each battery cell is independently connected to the mainboard using a commonly available connector, adding redundancy and ensuring that the life of the battery cells does not dictate the life of PowerCycle.

MkIII prototype mounted on a Brompton folding bicycle
MkIII prototype mounted on a Brompton folding bicycle

You can use PowerCycle to power Google maps while navigating on a trip, to extend your talk time on a morning commute, or as a transition device to adapt existing USB bicycle accessories to run off of dynamo power. Its broad compatibility allows it to charge digital cameras and gaming devices or to act as a direct power source for a reading light, speaker, or fan. Hardware enthusiasts will find it incredibly useful as a battery or uninterruptible power supply (UPS) for devices such as the popular Raspberry Pi computer.

MkIV prototype with an off the shelf USB LED light
MkIV prototype with an off the shelf USB LED light

Our philosophy in designing PowerCycle was to create an intuitive, simple and upgradeable device built to last. We plan for PowerCycle to be the first in a line of products with modular, upgradable parts.

PowerCycle is offered in two versions to suit different users’ needs. The standard version of PowerCycle can adapt power from a bicycle dynamo or charge from USB or a wall outlet using a provided micro USB adapter. For users who don’t anticipate charging their PowerCycle from a bicycle dynamo, the more basic “PowerCycle B” offers all the battery pack features of the PowerCycle without the additional cost introduced by the bicycle dynamo conversion, rugged barrel connector and accessories. This version comes with a simplified mainboard lacking the dynamo conversion circuitry and featuring a micro USB connection for charging the PowerCycle with a standard micro USB phone/tablet cable. This version is ideal for use as a miniature UPS. We anticipate offering upgrade boards to convert the PowerCycle B to a standard PowerCycle for around $15.

MkIV prototype powered from a Shimano dynamo
MkIV prototype powered from a Shimano dynamo

Small & Stylish: PowerCycle’s sleek design minimizes its height profile when mounted on a bicycle frame. It doesn’t look out of place in a conference room, or next to a tablet on a coffee-shop table. It slides comfortably into a pocket or purse. 

PowerCycle's aluminum body will be available anodized in graphite black, gunmetal grey, cardinal red, cobalt blue or raw aluminum (clear coat). PowerCycle will have a smooth surface finish unlike the rough surface of our 3D printed prototypes shown in the product photos.

Color swatches (approximate) for the anodized aluminum body
Color swatches (approximate) for the anodized aluminum body

Smart & Compatible: PowerCycle will automatically detect the charging capabilities of an attached device and optimize its power output for phones, tablets, gaming devices, digital cameras, and other USB electronics. For inexpensive devices that lack the circuitry to “talk” to PowerCycle, such as low-end speakers, lights, and fans, the user can flip a switch on the circuit board to increase compatibility at the cost of very slightly lower battery life.

PowerCycle MkIV prototype internals (mainboard & battery cells)
PowerCycle MkIV prototype internals (mainboard & battery cells)

Fast-Charging & Ready When Needed: When PowerCycle’s intelligent charging circuitry detects that an attached device is capable of supporting fast charging, it can charge up to four times as fast as a traditional USB 2.0 port or wall charger. The smart circuitry inside PowerCycle also allows it to hold a charge longer. Unlike most modern electronics that fully drain when not used for weeks or months, PowerCycle can go years without draining its battery. Even with the smart circuitry turned off, the full drain time for PowerCycle is approximately 500 days.

Bar height = charging speed, taller is faster
Bar height = charging speed, taller is faster

Powering Your Day: Connected to a bicycle dynamo, PowerCycle will continuously charge a connected device for as long as you are pedaling. When unplugged and used as a USB battery pack, PowerCycle's large internal battery provides ample charge for most devices. The graphic below provides rough charge estimates for current-generation devices. Older devices will usually get more charges.

Charging capacity of a fully charged PowerCycle
Charging capacity of a fully charged PowerCycle

PowerCycle’s internal battery can fully charge a latest-generation smartphone with a 4” or larger screen about twice, which should translate to a about 20 additional hours of talk time. Users with iPhones, smaller screen smartphones or older models without an extended battery can reach between three to four full phone charges, or about 30 additional hours of talk time. Current generation portable gaming devices such as the PS Vita or 3DS can fully charge at least twice, translating to an additional 7 to 12 hours of gameplay. Devices without a battery such as fans, LED lights & Raspberry Pi computers can be powered directly with PowerCycle acting as the device's battery, or as an uninterruptible power supply (UPS) if placed between a wall charger and the device (Raspberry Pi is a trademark of the Raspberry Pi Foundation).

MkIV prototype used as a UPS for the Raspberry Pi
MkIV prototype used as a UPS for the Raspberry Pi

User Repairable & Built to Last: Unlike almost every other portable battery pack on the market, PowerCycle’s lifetime is not limited by its original batteries. Replacing or upgrading the internal parts is as easy as removing a single screw. The internal batteries are connected to the circuit board with an easily inserted JST connector found on battery packs commonly available from many resellers. For customer convenience we also plan to make replacement batteries and circuit boards available for purchase. The main enclosure is made of extruded aluminum that has been anodized to outdoor specifications to prevent scratches and slow corrosion, and the end caps are made of an impact-resistant plastic.

MkIV prototype partially disassembled
MkIV prototype partially disassembled

Choose Your Version and Upgrade Later: Since PowerCycle is a modular design with user-replaceable parts, users can invest in the version that makes sense for them now and upgrade later if desired. We don’t believe in making users pay for features or parts that they don’t need. For electronics enthusiasts, cyclists who don’t use a bicycle dynamo, or anyone else not looking for that feature, PowerCycle B represents the best value for money. The PowerCycle B main board can be upgraded to the full version at a later time if desired for about a quarter of the cost of the standard PowerCycle.

Made in the USA: The manufacturing of the aluminum enclosure and end caps and the assembly of the circuit board and final product will be done in the United States.

Beta Access: We are committed to producing a high quality, thoroughly tested product. As a team of two, we lack the resources to test PowerCycle in every possible scenario by ourselves. We'll be running a beta program to help enlarge the testing pool, and we want to offer access to the beta program to a small group of interested backers.

If you are excited about PowerCycle, want to get your hands on one as soon as possible, and are interested in helping us test and improve the product during its pre-production stages, you might want to consider pledging at the beta access tier.

At this reward level you won't have to wait until production commences; we will be sending out PowerCycle beta units soon after the Kickstarter campaign ends. As we get feedback and go through a couple more board revisions you will get updated electronics. When we 'go gold', you will also receive the production version of PowerCycle (board and case). 

Please only purchase access to the beta program if you really want to test PowerCycle! If you do decide you want to be part of the beta program you will need to sign a basic beta contract, with the following key points:

  • You promise to use PowerCycle and give us feedback
  • You agree not to resell the PowerCycle beta and may not transfer membership in the beta program or your beta unit to anyone else
  • You are not employed by any company manufacturing a competing product and will not duplicate or distribute our designs without our permission

We will send the full beta agreement to those who pledge at the beta access level prior to completion of our funding period. Of course, if upon receipt you don't find the agreement acceptable, we will fully refund your pledge. Additionally, when we ship the final product the beta agreement will be voided.

Community Interaction: We don't see Kickstarter as just another way to raise money. Kickstarter is an incredibly valuable resource to connect users and developers who share a common interest in bringing awesome products into being. For those who like to talk directly to the developers of the projects they back, we want to connect with you throughout the production process. Really, if you've read this far you are probably exactly the kind of person that we want to hear from. These are a few of the ways we are planning on keeping in touch with you:

  • As expected, backing automatically gives you access to the backers' forum. At any time you can hop on and have a discussion with your fellow backers about PowerCycle.
  • We will be organizing regular livestreams where you can directly ask us questions. We will try to have something interesting to show as well during these livestreams, or during project updates, for instance we can discuss electronic or mechanical design, battery technology, our manufacturing process and experiences - or possibly drone on about how we use 3D printers to rapid prototype our products.
  • You can always e-mail us questions at or pepper us with tweets @PowerCycle_Devs on Twitter.


Our T-shirts!
Our T-shirts!

We've made a few awesome t-shirt designs for those of you who like to wear clothing and/or would like to help support the project. Choose between one of these delightfully geeky t-shirts. They are perfect for wearing while out for a ride on a warm sunny day or for blending in with the shadows while skulking around a basement server room.


  • Dimensions: approx. 3.9 in (100mm) x 2.4 in (60mm) x 1 in (25mm)
  • Weight: approx. 5.25oz (149g)
  • Battery: 5200mAh li-ion*
  • Input: 5-12V DC/AC 1.75A max**
  • Output: 5V 1.9A max
  • Overcurrent and overvoltage protection
  • Charges from USB (cable included)**
  • Charges from 5-6V power adapter (not included)
  • Charges from bicycle dynamo system*** (cable included)**
  • Rugged aluminum casing available in a variety of colors (prototypes shown in images have been 3D printed in plastic)
  • Compatible with Apple, Android, Windows Phone, Blackberry, or any other mobile device that utilizes USB charging

* Battery capacity will be at least 5200mAh, but may be increased.

** AC and dynamo charge features are only available in the standard version of PowerCycle, not the PowerCycle B model. Custom charge cables not provided with PowerCycle B (it uses a standard micro USB cable to charge).

*** Dynamo not included!

Production Plan

PowerCycle will require four distinct manufacturing phases. PCB Manufacturing, Extrusion Manufacturing, Injected Molded Parts Manufacturing, and Final Assembly and Packaging.

Our PCBs (Circuit Boards) will be manufactured, verified, and assembled with their final components at a production facility, most likely in Eastern Europe, at which we have a past working relationship.  We're planning a beta period of about 2 months before we have ironed out all the bugs. After that, we also need about 2 weeks to prepare the design for mass production (called DFM: Design For Manufacturing). Then, final production will take another 10 weeks or so.

From here the boards will be shipped to one of our offices, either in the Netherlands or the US. Here the boards will be extensively tested in-house using a custom test rig. The test rig is designed to help us catch board assembly errors before we move onto the next phase of product assembly. 

In parallel with the electronics manufacturing we will be sending out orders to produce the aluminum shell at a local aluminum extruder in the US. We've looked for facilities that are partnered closely with local anodizers, or do their own anodizing. We've found a few that seem easy to work with and excited to help us produce a top quality product. The process of having a custom aluminum profile manufactured typically takes about 8-10 weeks. Unlike the electronics, the shell design is actually ready for mass manufacture right now.

The end caps of PowerCycle will be injection molded. We'll work with a US injection-molding facility to ensure that the end product is of great quality. We have been in touch with dozens of US and NL based injection molders in the past 7 months and already refined the design for manufacturability. However, we do expect more revisions along the way as we work with our molding partner and receive back pre-production test runs prior to the final order. This process will take at least 10 weeks.

The battery cells for PowerCycle will be purchased from a top-brand manufacturer, and will be packaged at a facility most-likely state-side.

Final assembly and packaging will be done locally under personal supervision, with one last quality test done before the units are packed and sent out to our backers.

Risks and challenges Learn about accountability on Kickstarter

We have worked hard to advance this project to the point where we feel comfortable asking for others to invest in it. We have made four generations of prototypes and have been using the PowerCycle extensively in our daily lives for the past five months.

Before we ship out the final product, we want to get our latest prototype out to as many beta testers as possible. The more people involved, the better the odds of us catching a previously unknown bug. Since error conditions may be triggered by a rare combination of factors, only extensive testing with as many users as possible can help us ensure the best possible reliability. We are focused on delivering a solid first-generation product that is satisfying and reliable. Exposing PowerCycle to a larger audience early in the production cycle means a better end product!

We have been working closely with potential U.S. manufacturers to review and revise our designs, making changes throughout the development process to reduce costs and ensure manufacturability. When we get funded we will be entering the mass manufacturing stage which poses new challenges, including possible delays and issues with the quality and assembly of parts.

Manufacturing in the United States is more expensive than going to Asia, at least on paper. However, it simplifies communication and allows for tighter management and better quality control. Stateside production will help during the initial stages of manufacturing when we will need to work closely with manufacturers to optimize our tooling design to ensure smooth production and a good fit between parts. We have budgeted our part designs with some room for error, but it is important for us to keep the manufacturing yield high. We might be paying more per part in the US, but if we have fewer manufacturing errors going local is a better deal.

Quality control is also a major consideration in delivering our product. We plan on implementing a multi-tiered quality control system that tests for manufacturing errors before and after final assembly. Additionally, we plan on implementing a parts tracking system to help us uniquely identify and track each battery, circuit board, and fully assembled device. Therefore, if we make a mistake along the way we will have a system in place to find that mistake quickly and fix it.

We are new to this, and we expect bumps along the way. Our goal has been to take risks into consideration and to give ourselves flexibility in our timeline and budget to account for the problems that will inevitably crop up.


  • No! PowerCycle can adapt the power output of bicycle dynamos that output 3-6V AC (most dynamos), but does not include one. We wanted to focus on making the best battery pack/dynamo adapter and did not want to add on the design challenge of a dynamo itself. There are very good hub dynamos on the market in the $100-$150USD range with years if not decades of reliability testing, and much less expensive bottle or tire dynamos in the sub $25 range. We could not see producing something that would offer an advantage to the end-user over these existing systems. Perhaps in the future that will change, but we don't anticipate doing so at this time.

    If you are considering purchasing a dynamo at some point in the future we would still recommend the standard PowerCycle. This also works with standard USB chargers, so it is perfectly usable by someone without a dynamo (it just requires a special cable that we will provide in the reward).

    If you know that you will never buy a bicycle dynamo, the PowerCycle B is the best option. It doesn't need a special cable (it uses micro USB to charge, just like most cell phones) and has the same battery capacity and fast charging of the standard PowerCycle.

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  • No, PowerCycle is not officially waterproof, but it will survive a shower or even a splash into the water just fine. Here's the reason: USB connectors - at least commodity parts - are by design not waterproof and it would take a very intricate construction to make this part waterproof (and keep it waterproof when a user removes and reinserts the board). What we did instead with the design is to use a conformal coating on the mainboard that shields the electronics inside from water. This still leaves the internal battery connectors which can corrode when they are left in water for too long. Whenever you decide to give PowerCycle a bath, make sure to give it the opportunity to dry afterwards! One last, more bureaucratic reason why PowerCycle will not be officially waterproof is because an IP67 or IPX-rating would cost us a lot of money in this low volume.

    We are currently in the process of designing a true waterproof casing for PowerCycle. This will be slightly larger than the unit itself, enclose the PowerCycle and shield both connectors. To produce this in relatively low quantity (in mass manufacturing terms, even 1000 units is 'low quantity') will cost too much to include in the base package, and not everyone is going to want one. That is why we decided to create this as a separate accessory.

    Don’t back PowerCycle assuming that we will be able to later fund manufacturing for this accessory! That being said, it is a priority for us and will be a stretch goal.

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  • The short answer is yes, but with the caveat that you can't buy the full battery assembly off-the-shelf from a regular electronics store.

    Each of our batteries has two main parts: the battery cell and the connector. They are joined by a short wire.

    We started out using prismatic cells (what you'd find inside a cell phone battery if you took it apart) but found that these were too difficult to guarantee availability for in the future (they are not standardized). We switched to 18650 cells, which are a very common type of Li-Ion battery cell (you can get them off of Amazon, for example). Each cell is connected to our mainboard by a wire and a JST-XH connector, which can be inserted/removed many times and won't have the rust & vibration issues that bare metal spring clips would have. These connectors are commonly used in the hobby airplane/RC market, so they should also be relatively easy to find.

    To make a compatible battery cell for PowerCycle you would have to buy an 18650 (this should be very easy) and either have a JST-XH connector put on it by an RC hobby store, or cut the old battery cell wire and crimp/solder your new 18650 to the cable from the cells that we ship with the PowerCycle. This is actually pretty easy and within the reach of most hacker/maker types, but of course we should state that you do this type of work at your own risk! We plan on selling pre-assembled replacement cells during the lifetime of the product.

    We will provide step-by-step instructions (probably in video form) on how to make your own batteries for PowerCycle when this project gets kickstarted. So even if you don't trust us to actually support PowerCycle after we've fulfilled all the orders, you can still repair and upgrade your unit for many years to come.

    Important note: PowerCycle only works with 18650 Lithium Ion or Lithium Polymer cells. It does NOT work with NiMH, NiCd or LiFePO4 chemistries. You can recognize this difference by the nominal voltage of the cells: Li-ion and LiPo has a nominal voltage of 3.6 or 3.7V, while the other chemistries have a lower voltage and will certainly damage if you try to use them in PowerCycle.

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  • Yes, provided your solar panel outputs a voltage between 4.5-6.2V. Most solar panels have a 5V USB output, and PowerCycle is just fine charging from that.

    Double check the specifications of your particular model of solar panel though! There are some solar panels that output 12V or 19V - this will not work in combination with PowerCycle without a 12V to 5V converter. However, many of these solar panels come with automotive ('cigarette lighter'-style) 12V to USB adapters, so you might still be able to use it with this extra converter in between.

    If you plan on using PowerCycle only with a USB-output solar panel, we recommend choosing the 'B' version instead of the 'standard' version.

    Last updated:
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    SUPPORT THE CAUSE: You'll receive project updates via e-mail and our sincere thanks. If we're funded, you will know that you helped us bring this awesome product to market!

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    T-SHIRT: Choose from one of our awesome T-Shirt designs: "I Sweat Electricity", "Escape Fossil Fuels" or "Resist". See the project description for a preview of the designs. Shipping in the USA is included.

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    EARLY BIRD SPECIAL - POWERCYCLE B: As one of our early backers receive the PowerCycle B at a $5 discount. This version of PowerCycle does not support bicycle dynamo input - but can be upgraded later. Perfect for a non-cyclist or someone who does not anticipate purchasing a bicycle dynamo. Get PowerCycle B in your choice of the following colors: Graphite Black, Gunmetal Grey, Cardinal Red, Cobalt Blue or Raw Aluminum (clearcoat). Shipping in the USA is included.

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    POWERCYCLE B: This version of PowerCycle does not support bicycle dynamo input - but can be upgraded later. Perfect for a non-cyclist or someone who does not anticipate purchasing a bicycle dynamo. Get PowerCycle B in your choice of the following colors: Graphite Black, Gunmetal Grey, Cardinal Red, Cobalt Blue or Raw Aluminum (clearcoat). Shipping in the USA is included.

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    EARLY BIRD SPECIAL - POWERCYCLE STANDARD VERSION: As one of our early backers receive the PowerCycle Standard Version at a $5 discount. This is the full PowerCycle with dynamo capabilities. Get PowerCycle in your choice of the following colors: Graphite Black, Gunmetal Grey, Cardinal Red, Cobalt Blue or Raw Aluminum (clearcoat). USB charge cable and dynamo cable included. Shipping in the USA is included.

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    POWERCYCLE STANDARD VERSION: This is the full PowerCycle with dynamo capabilities. Get PowerCycle in your choice of the following colors: Graphite Black, Gunmetal Grey, Cardinal Red, Cobalt Blue or Raw Aluminum (clearcoat). USB charge cable and dynamo cable included. Shipping in the USA is included.

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    BETA ACCESS: For those who want to help us perfect the PowerCycle we are offering very early availability and direct communications with our development team. You will receive one version of the next beta board, one set of battery cells, and one 3D printed enclosure upon completion of our Kickstarter campaign. Between now and the final release time of March 2014 you will receive at least two updates of the control board (including one final production version of the board) as well as one final production version of the case. This tier will be subject to a beta agreement, meaning among other things that you won't be allowed to resell the prototype parts or transfer the agreement (although you will be allowed to do what you like with the final version product that you receive). Please only purchase this tier if you are interested in actively giving feedback on your PowerCycle experience. Get your PowerCycle production version in your choice of the following colors: Graphite Black, Gunmetal Grey, Cardinal Red, Cobalt Blue or Raw Aluminum (clearcoat). USB charge cable and dynamo cable included. Shipping in the USA is included.

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Funding period

- (30 days)