Hacking an External Power Source for a Light BLue Bean

*Disclaimer: soldering a battery should be done with extreme caution and safety gear as heating up the battery could cause splosions!

For this post, I wanted to give you folks a simple hack that can be done if you run out of options, or don't have the proper equipment to get the job done(I endorse getting the proper equipment).

So recently at a Coffee & Code session I was working on relaying information through Bluetooth Low Energy from my 90 degree motion sensors instead of having to wire them to another device to capture information.

The problem is that the draw from the 2 motion sensors and the light blue bean was going to pull just a few too many amps for the typical coin cell battery to handle for longer than an hour or so. This meant I was going to have to power the bean through another design. I didn't want to permanently attach a power source to the bean, so I decided a rechargable power source would be an ultimately better solution.

Here is what I needed:

  • A light blue bean
  • Duracell Rechargable power source(1150 mAh)
  • an FTDI cable with 5A, 3A, and GND capacity
  • 3 F2M Jumper cables to attach to the FTDI
  • A Coin Cell Battery


My Power Source

The Bean actually has a 3.3A power supply requirement, so this was the perfect time to utilize the 3.3V prong on the FTDI cable. In this case, all we were doing is stepping down coming out of power supply. The sensors required 5A, so we will connect them later. I simply soldered(see disclaimer) the ground, and positive of the male ends of 2 jumpers to the battery.

The end result was the capability to step down out of the USB port on the Duracell rechargeable power source to 3.3 for the bean, and then step the 5A to the motion sensors, and then pass the signal to the A0 and A1 pins on the bean, thus giving me the ability to push data over BLE to a Bluetooth Device within range!

After it was all said and done, we attached Standard Firmata onto the Light Blue Bean, and hooked it up to our two motion sensors. A short bighht of bean-io, and we had the ability to pass through johnny-five, and record data from our 90 degree angle PIR sensors. I built a pretty fun script to make this work(you may need to put your own bean-io code in).

Here is the johnny-five source for two PIR sensors

Here is the finished product!

side note: I also built a wrapper for octoblu you can tie your data straight to iot with.

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