We use a lot of batteries at ITP. Most of these end their life as industrial waste in our “Techo-scrap” bin, eventually to be carted off by an NYU contractor to parts unknown where their chemicals perhaps leach into places unthinkable? Maybe, not. Hopefully they’re treated with great care, but it certainly would be far more environmentally sound for us to be reusing our batteries instead of handing industrial waste off as somebody else’s problem.
Therefore to get things greener, I set up a brand-new battery recharging station to be shared by all of our students and faculty. We can charge commonly available Nickel-metal Hydride (NiMH) AAA, AA, C, D and 9 Volt cells. There’s also a small Lithium-ion coin cell charger, for special 3.6 Volt rechargeable coin cells. To help answer technical questions, a manual for each charger has been laminated and attached to the recharging station.
More information about the devices and how to obtain batteries is available on our Physical Computing site.
A few interesting developments have happened over the holidays with XBee radios.
- The company (formerly known as Maxstream) has rebranded the radios (formerly known as the XBee Series 2). From now on you’ll be calling them the Digi XBee ZNet 2.5.
- The XBee ZNet 2.5 name coincides with brand new firmware. This update includes bug fixes and most importantly, automated transmission of I/O readings from the analog and digital input pins. The firmware isn’t posted on their site yet, and it isn’t documented. If you’re at ITP, ask me for the 1×40 files. Otherwise, talk to Digi support.
- I’m working on a version of the XBee library for Processing to parse the undocumented ZNet I/O packets. That will get posted here once I feel that it’s working.
- We were able to get XBees running off of an unregulated rechargeable coin cell. The Lithium-ion 2450 works for about an hour in my tests, without sleeping the radios at all.
More to come…
People ask me all the time which battery they should use for their Arduino project, or how long an XBee will run on a specific type of battery. Rather than continue to give vague answers, I decided that it would be much more helpful to generate some real-world battery life results for Arduino projects and XBee mesh networking radios. There were a lot of surprises. The results depend of course upon which battery you choose, but everything else makes a difference too. Changing the duty cycle of a single LED doubled battery life on an Arduino project. Simply sleeping an XBee radio between transmissions generated a whopping 1470% increase in battery life. In a few cases specific types of batteries failed completely–probably the most helpful test result of all.
Use the real-world battery life results to help choose which setup is right for your project. You can also use my Battery Test program in Processing to run your own tests. Send me any well-documented results and I’ll gladly add them to the list.
Hey, bandwagons are for jumping on, so I created an ITP AlumniBlender Facebook application that dynamically displays all AlumniBlender headlines and authors. You can add it to your profile.
Thinking of making your own feed app? Try reading a bit of their getting started information and check out the great tutorial on HowToForge for specific resources, including the ever-useful Magpie RSS.
The ITP AlumniBlender put on quite a bit of weight over the holidays as I mined databases and tracked down more of our ilk. It’s now almost tripled in size with feeds from five continents and alumni that span 17 years of the Interactive Telecommunications Program. From sneakers to scaling, and from tempers to tweetups, there’s plenty to read with new content arriving daily. Enjoy.
