NXT on solar power

Just as I was thinking about what it would take to make a mars rover with the NXT, I found the dSolar panels from Dexter Industries. How cool is that, a mars rover that actually runs on solar cells!

However, $100 seems a bit expensive for such a nice-to-have feature. Looking around on eBay revealed you can get more power for half the money, only it doesn’t come in a LEGO friendly package.

I bought them anyway, and documented the customizations. Soldering iron required!

[update]: It is recommended that you put diodes between the panels, see comments below.

So basically I connected the panels in parallel with a few plugs from an old computer. The whole thing is connects to the NXT via 2 fake batteries made of hot glue cartridges. To prove it really works:

I can’t wait to make a robot with these.

3 thoughts on “NXT on solar power”

  1. Good idea, but I think it is a good idea to put at least one diode in the wiring so that it will not work if you connect it up the wrong way round.

    There is a slight voltage drop across the diode (usually < 1v) so you might need to add another solar panel if the output is low to begin with. better than risking destroying the NXT though.

    A better alternative (but with greater voltage drop), is to use 4 diodes or a ready-made rectifier. This means that it will always work, no matter which way you connect the wires.

    http://www.google.co.uk/imgres?imgurl=http://www.kpsec.freeuk.com/animated/brect.gif&imgrefurl=http://www.kpsec.freeuk.com/components/diode.htm&h=172&w=298&sz=5&tbnid=aGAxALjM2Uw54M:&tbnh=69&tbnw=120&zoom=1&docid=ZSKVV-qtFWMOuM&hl=en&sa=X&ei=saZgT_3mKsTa8AO8-sjYBw&ved=0CDYQ9QEwAA&dur=20

    Like the crane btw, very simple but effective.

  2. Hi again. Looked through ebay for solar panels and see that it is recommended that you put a simple rectifying diode (search for 1n4* diode* to get the lowest prices) in the wires from each panel. I think this is to stop a shaded panel from getting power shoved in by other panels in better light.

    Only necessary if you are running the units in parallel.

  3. Thanks. The panels I bought included USB headers and diodes in the package, I guess I should attach them, as your recommend.

    I would hope the NXT is protected against “kids” putting in “the batteries” the wrong way around, but the point about shade is very much valid regardless of NXT protection.

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