Here's a 9V battery, with the housing removed.  It's actually six AAAA batteries wired in series.  Handy if you run out of AAA and you have a 9V laying around.  They're a little smaller than AAA batteries but they work fine.  It's not hard to imagine 13 or so of these strung together fitting into the 6" TPU.

300mAh *13 = 3.9 Amp - Hours.
9*13 = 117 Volts.

You should be able to pull a full amp for 20 minutes before the batteries start to precipitously crash, according to typical discharge curves for single 9V batteries at 1 Amp.

Quote from: kames on April 10, 2008, 11:10:44 PM

@zerotensor

Open a book and read how to calculate the power when the batteries are connected in series.
Better, just test your idea and see that your calculations are wrong.

Kames.

It's gonna be a while before I have the extra cash to dump on a dozen batteries, but it will be done.

Check yourself, Kames.  Amp-hours is battery capacity, not power.  Say you have 2 batteries each rated at 500mAh.  That's 1000mAh you have total.  Attach a load that draws 1 Amp across one of the battery's terminals.  After about a half-hour, you will have drained all the juice from your battery.  Now, swap in the fresh battery.  We get another 1/2 hour of operation at 1 amp.  We see that the rating of the battery is a measure of how much energy we can extract, not power.  Twice as many batteries, twice as much energy there to extract.

You say this doesn't work if you connect the batteries in series.  I disagree.  The capacity doesn't go away no matter how you hook them up. 

That is a good question. I find Steven's 6 in. TPU intriguing since he strayed from the usual slim toroid design and made it thicker.  Interestingly, it has enough space to fit a row of 9V batteries perfectly. Each battery can weigh an estimated 34 grams.