B-Squares

November 7, 2011

B-Squares

Out of the many nifty projects I’ve seen on Kickstarter, my favorite hardware project was B-Squares. Each square has alternating positive and negative magnetic terminals, allowing you to easily and reliably connect squares electrically.

I bought the super recipe kit, and it showed up a few days ago. The kit I purchased includes five solar squares, two battery squares, two LED squares, two Arduino squares, and four proto-board squares.

left to right: solar square, LED square, battery square without cover, battery square with cover; Arduino square, LED square, solar square

Today was the first clear sunny day where I had the kit handy, so I took a selection of squares outside along with my multimeter.

Having little or no clue about electronics and even less clue about solar cells, I measured the output voltage of each cell in direct fall sunlight. Each cell gave almost exactly 3.75 volts.

I really enjoy playing with this kit, it’s worth what I paid for it, but I still have questions.

First, the battery square seems to have a built-in NiMH recharging chip, visible in the picture below.

B-Squares battery

To charge the battery square from the solar squares, do I connect the solar squares to the battery square as if the battery square were powering the solar square? Will there be any problems if I connect all five solar squares to a single battery square? Will I fry the Arduino Pro square if I hook all five solar cells to it?

If I connect two solar cells directly together and connect them to an LED square, why is the LED square not powered? If I flip one of the solar cells ninety degrees, the LED square gets more than a single solar square worth of power. That contradicts what I expected, are there diodes in the squares doing something?

Perhaps it would help if I had the schematic for each square. I’d like to find out which charging chip is being used in the battery square and hack in charging and full LEDs. Schematics would also tell me whether the Arduino Pro is current limited or otherwise unlikely to fry when connected to two battery squares and five solar cells.

My electrical engineering friends dislike the minimalistic qualities of the B-Squares, they’d rather have a raw AVR or raw MSP430. Most of them feel the same way about the Arduino, feeling that it sacrifices too much control for not enough convenience. But for me, this is the right level of convenience. While I do wish the B-Squares had some way to transmit data through the magnetic contacts, I’m happy they were produced.

If you’d like to buy your own B-Squares, they’re available online at seeedstudio.