Technology Casserole

Do you spend a lot of time using your smartphone more for it’s “smarts” than it’s “phone”? Are you Qik streaming a concert, or trying to check in to every single shop on the Boardwalk with Foursquare? Taking Google Tracks on an all-day hike? Then you need some serious battery power.

Facing these very issues, this is what I assembled. It’s called the Minty Boost and it’s available in kit form from Adafruit Industries. If you’ve soldered before (and have an Altoids gum tin to re-purpose) you could have it together in under an hour. The website has all the details for tweaks you can do to the kit as well as a description of how it was developed.

My experience using it with my Nexus One has been positive. It seems to be able to put about 50% charge into the phone from the rechargeable batteries I have been using.

Things to note:

• The discharge profile ends with the batteries getting quite warm as the regulator sucks every last electron to maintain 5V on the USB header.
• So far I have only used NiMH, but alkaline calls are also compatible and should do in a pinch.
• You do need to have a cable for your device (this is where the standardization on micro USB for cell phones will be handy).

The only concern is keeping an eye on the charge status since, on my Nexus One and my G1 at least, it will still think it’s charging after the batteries are drained past the point of providing power (after it’s gone all hot, as mentioned above). At that point I imagine it would be best to unplug the Minty Boost.

So go build yourself one! Or maybe try one of the other projects at Adafruit.

A few weeks ago, the seasonal solar lighting merchandise showed up at the IKEA store here in Orlando. It’s all priced quite well for outdoor solar-powered gear so I went and picked up a few things to play with. I then promptly disassembled my new lights and here is what I found.

This is the inside of the power module for the 3 uplight kit. (It’s the same module and batteries that are found in the 8 globe light chain – I got one of those from the as-is section last weekend.)

Four screws later and you can see the two 1000mAh NiMH batteries that are mentioned on the package, presumably that’s all the panel could charge in one day since that’s very little capacity for a AA rechargeable. It will run the 3 banks of 3 LED’s all night if they fully charge, however. The standard size battery means they can easily be replaced after daily charging cycles deplete the capacity.

The problem is, when they are mostly-discharged the lights will start to flash on and off as the battery circuit loads and unloads. Depending on how well the LED driver is designed that could greatly shorten their lifespan. A low-voltage cutoff or adding a small amount of hysteresis through current feedback should prevent this and I plan to experiment on my light chain’s power module to see if there is a simple solution.

In the interim I am quite happy with my lights, and so are the palm trees. I am trying to find an excuse to get some of the totally self-contained dome-shaped units as well – I just need somewhere to put them…

Thanks to the article on IKEAfans for piquing my interest.