Have you experienced that moment of success when you complete a project on your Arduino? This glorious victory when the temperature displays on your LCD, or your LEDs flash in perfect succession. I've spent many long hours on projects seeking this moment, only to have it shattered by the realization that my creation is shackled to the USB port of my computer or the cord on an AC adapter. Sure, you could wire up a battery pack of sorts with a costly 9V battery or a pack of AAs; only adding to the amount of delicate circuitry. We knew there had to be a better way...
After some trial and error, we have found the better way.
NightShade Electronics is proud to introduce to you...
What is it? The energyShield is a rechargeable lithium-polymer battery in the form of an Arduino shield (Uno/Leonardo Compatible). It has three main internal functions including a circuit to boost the battery's nominal voltage of 3.7V to 5V; a lithium-polymer battery charging circuit; and an on-board fuel gauge IC which allows for the measurement of battery voltage, current, and accumulated charge by means of a Two-Wire Interface (TWI/I2C).
All energyShields will include:
- energyShield (with everything soldered except the headers and battery)
- Battery (with bare leads)
- Header Pins
- Power Adapter (U.S. Plug Type, 9V DC)
- Contained in Arduino Shield Form-Factor (Uno and Leo/R3)
- 5V Output (and 3.3V when attached to an Arduino)
- 500 mA Output (Final version will be HIGHER!)
- Integrated Charging Circuit
- Fuel-gauge IC - Monitor Voltage, Current, and Charge via a Two-Wire Interface (TWI/I2C)
- Fully Functional Arduino Library
- On/Off Switch
- Charges from Standard Arduino Power Adapter (7.2-20V)
- Powers Arduino While Charging
- @ $15,000 - 3.3V Output and Breakout Header for non-shield use
- @ $20,000 - Charges via USB micro cable
- @ $25,000 - Chages via solar (PV) cell without power interruption
- Temporary Projects
- Remote Data Logging
- R/C Vehicles
- Any Time You Want Hassle-Free Power
How is it Unique?
It's not a secret that there are other batteries out there for the Arduino. However, there is no other rechargeable Arduino battery that includes built-in charging circuitry, offers high current sourcing ability, and contains a fuel gauge within the footprint of the Arduino . Here at NightShade Electronics we created our first working prototype a couple weeks before Christmas and, even today, we are still fascinated by the ease at which you can power a project with the energyShield. There's no expensive, disposable batteries. No delicate power circuitry. Just a securely attached shield with an On switch and DC power jack for recharging. It's easy and it is FUN!
After we formed the initial concept of the energyShield we went right to work designing our first prototype. Our first design was... less than impressive. Sometimes it functioned as it was supposed to and, at other times, it lost some of it's magic smoke. While addressing a simple problem we had created a complicated solution. At that point we threw out the design and started again with a blank canvas. We began again with a more simple, yet more elegant design. The operation is now more intuitive, and the energyShield is more robust. In our second iteration we had achieved everything we had set out to do. We have created a shield that provides a project with power at the flip of a switch.
But, we're not stopping here. We already have a list of changes to make to further improve the energyShield. As you read this we are working on our third iteration of the energyShield. We are fixing a couple of bugs and adding to the list of features.
Where you come in...
We have brought the energyShield to Kickstarter, because we need your support to fund the first production run of the energyShield. We have a manufacturing plan in place and we are in contact with various suppliers who are ready to source the parts to us. The only missing piece is your pledge. Your pledge will provide the capital necessary to place a production order large enough for it to be economical. On behalf of the entire NightShade team, Thank you!
Atmel article featuring the energyShield!
The robot in the video, project, was designed as a power source demonstrator. As such, it does not have any power source of its own. The Arduino seen on the top of the robot has wires soldered to the bottom of it to control and power the screen and motors.
This campaign is not about project though, so back to the energyShield!
Presently the energyShield has a capacity of 1200 mAh, a nominal current sourcing of 500 mA and, at full charge, a maximum current sourcing of 825 mA. We are looking into improving the current rating of the board to allow the energyShield to power even more demanding projects. The reason for the varying current limitation on the energyShield has to do with the output voltage (5V) being stepped up from the battery voltage (3.7V nominal). Because the battery voltage is lower than the output voltage, the current from the battery is larger than the current drawn from the energyShield at 5V. Assuming that the power from the battery is equal to the power used at 5V, the battery current (100% efficient) can be illustrated as such: I(bat) = I(out) * 5V / V(bat). What this says is that as the battery dies (voltage decreases), the current drawn from the batter will increase. Therefore the load must be limited, so that the current drawn from the battery does not exceed the battery limitation, even at the lowest battery voltages.
Below is a graph which represents data recorded from the energyShield via the TWI interface.
This data was recorded as a fully charged energyShield was fully discharged under a 245 mA load. This constant load is represented by the lowest curve on the graph (Output Current). It reflects that over the entire life of the battery the current output from the energyShield to the load was a constant 245 mA. The next curve to take note of is the "Output Current, 100% Eff." This is the current that would have been output if the energyShield was 100% efficient at boosting the battery voltage to 5V. I won't hold you in suspense . . . . . . . . . . . . . . ok, maybe for just a minute . . . . . . It is NOT 100% efficient. Actually it is about 83% efficient. What this means is that you will only be able to use about 83% of the electricity that was stored in the battery. Here in Florida the amount of electricity in the battery costs about 0.0051¢, so I would say that's not really a big deal. The final two curves, Battery Voltage and Battery Current, work together. This illustrates why you can not pull the rated current capacity from the battery when the voltage is boosted. As the battery power is consumed the battery voltage decreases. As the battery voltage decreases the amount of current drawn from the battery must increase to maintain the constant output current. As the battery nears the end of its life the current drawn from the battery is almost double the amount output, which could easily over draw the battery. We are looking into some modifications that could lower the amount of extra current required towards the end of the battery life. This will allow the current rating of the energyShield to be even higher than it is today.
During Kickstarter (Feb - Mar)
- Order samples from suppliers: Because the components such as the battery and power adapter are being produced by companies overseas, we expect the shipping to take a couple weeks. We want to complete this early on so the schedule is not held back.
- Design and order the next revision of the energyShield: Once the next (and hopefully final) prototype of the energyShield is designed, the process of ordering as assembling it will take 2-3 weeks. We plan to complete the next design during the Kickstarter campaign, that way we will be ready for production soon after the campaign ends.
- Finish writing Arduino library for the energyShield: We have a preliminary version of the library right now, but want to have the library completed before we send our backers their energyShields. Write documentation for the energyShield The energyShield is extremely simple to use, but there are several advanced features and specifications that will be explained in the documentation.
Post-Kickstarter (Mar - Apr)
- Design the final version of the energyShield: This will be the production version of the energyShield. Here we will make the last little tweaks to the design.
- Order production proof of the energyShield from the PCB manufacturer/assembler: Before the manufacturer produces 100’s or 1000’s of the energyShield we are going to have them send us a proof; just one or two energyShields produced exactly as if they were part of the production run. This gives us the chance to catch any problems before we have a plethora of defective energyShields.
- Place production order to PCB manufacturer/assembler and suppliers: Once we have tested and approved the energyShield proof from the manufacturer we will give them the go-ahead to make the energyShield for the masses.
Production Completed (May)
- Packing and Shipping the energyShield: Once we have received all of the completed parts of the energyShield, we will pack them into kits and mail them to you!
*Some Assembly Required
The energyShield will be shipped to you needing minor assembly. You will need to solder the header pins and battery to the board. This helps to prevent damage to the pins during shipping and it avoids costly FCC certification; as the energyShield is a sub-assembly sold in a kit.
Risks and challenges
We have already overcome most of our greatest challenges. Some of these included creating our prototype design, finding manufacturers and suppliers, and bringing this to Kickstarter.
Now our biggest challenges are securing distributors and telling people that the energyShield is ready for them! We have production plans in place. What we need now is for people to spread the word. Share this campaign with your friends on Facebook and Twitter and tell your favorite distributors (Sparkfun, Adadfruit, Maker Shed, etc.) that you want them to stock the energyShield.Learn about accountability on Kickstarter
- (25 days)