One of the biggest design constraints on a near-space remote sensing mission is power: how many voltages to supply, each subsystem's consumption (and how to minimise it), and how to deliver it.
As it happens, we're in luck. Everything to which we need to supply power uses USB: 5V at up to 0.5A. (Well, some parts might need 3.3V, but the CCP supplies that, derived from the 5V USB input.) This means we can consolidate a lot of the power management, but we still need to have a plentiful supply of electrons. Not only that, but the SPOT tracker, the ICP and the cameras each have their own inbuilt power storage. That just leaves the CCP, plus top-up power to anything that won't last the distance without.
Even though everything's using USB, and therefore one voltage, we still have to ensure that the voltage is stable. A lot of thought went into how to do this. We drew up circuits using Buck converters, went long and deep into whether to use rechargable or single-use lithium batteries (and how many, and in what configuation) - we even considered doing something fancy with a laptop battery and some neat power converters. And then we came across a little marvel: the Scosche GoBat II. In a little over 100gm, it contains a 5000mAH supply at USB 5V DC levels, capable of delivering 2.1A on one of its two sockets, if we needed that. (The other socket's rated for 1A.) And it's got all the power conditioning we need too. We've just taken delivery, and it's a neat little thing. Now, do we rip off the cool piano-black casing to save a few grammes?
But-but-but it's SHINY!
We've still to map the power draws for each component, but this gives us confidence that the payload will still be alive when it lands...well, just up ot the moment when it lands...
Last Updated (Thursday, 11 August 2011 23:54)