PriUPS BONUS! - Portable Power

I left you here in January...

I could just drop it here.  "I've got mine."  But I don't think I shall.  For one thing, this web site "just grew" and isn't as coherent as it might be - perhaps I'll get sufficient ambition to organize it a bit better and update some of its tentative beginnings.  For another, enough issues have been raised that it might be worthwhile to have an online discussion area devoted fairly strictly to the hybrid-as-UPS concept.  So give me a few (days|weeks|months) to catch up on my reading, get my moonbounce beacon back on the air, and pester the odd journalist. 

And now it's April.  My moonbounce beacon is back on the air.  I just sent an email to Scientific American in response to an article about hybrid vehicles in the April issue, which should count as "pestering the odd journalist."  Have I committed any acts of organization?  Not yet!  Have I created a "discussion area?"  Nope!  However, I had a minor epiphany yesterday that resulted, most uncharacteristically, in my making a telephone call.  This, in turn resulted in an answer that I hoped for, expected, and ultimately received.  The answer was "Yes."  The question was "Do your power supplies work on DC?"  The result is a big bonus for PriUPS followers.  Let me start from the beginning...

The W2ETI moonbounce beacon has a high-power amplifier that puts out 350W at 1296 MHz.  By the time the signal gets back from the moon there's precious few photons remaining, so the more power the better.  The previous amplifier could barely run 200 W and was unreliable; the new one shows stigmata of solidity.  The new amp requires 28VDC rather than the previous 12VDC, and so I had to dedicate two very expensive lab supplies to running it instead of the previous single supply.  This prompted me to look for something cheaper that would put out 28V at the requisite 50A.  Where did I look?  EBay, of course.  What did I find?  A bunch of switching supplies that had exactly the right characteristics:  220-240VAC in, 28V, 50A out, with the output voltage being somewhat adjustable from a bit below 24V to above 28V.  These supplies were really inexpensive because they only work on 220-240V.  Since the lab supplies also ran from a 230V UPS,  this was not a problem.  I did say "supplies" - the seller was offering 13 as a lot, and I ended up with them all.

Fast-forward to yesterday.  I was lamenting the state of my poor little airplane, which has had no exercise all winter, and whose battery, I'm all but certain, is 100% life-free.  We had a couple of warm days and I was thinking it might be fun to go flying, necessarily preceded by the not-fun of starting the airplane with a dead battery.  Airplanes typically have 28V electrical systems, which means you can't jumper them from a car battery.  The last time I had this problem, I had to take a big 115V UPS and yet another lab supply to charge the battery.  THOUGHT BALLOON!  Maybe I could use one of these switching supplies, which has enough output to not just charge the battery, but probably enough to start the engine!  BUT - but they only work on 230VAC.  At which time the AHA moment arrived.  I reread the spec, looked at the block diagram, and realized:  They have a full-wave rectifier on the input.  Which means they really work on 230V DC.  And who has a 230V DC connector in his car?  Yes!  I do, and you might, too.

Thank you for reading the above background babble.  In fact, all you really need to know is this:

• Switching power supplies with 230VDC inputs and 12V, 24V, or 48V outputs are readily available on eBay, and are very inexpensive.  (By very inexpensive, I mean under $100.  Sometimes, with luck, well under $100.)
• If you have any of these voltages at suitable currents, you can use an ORDINARY UPS instead of searching for a monster like the one that I used in the PriUPS project.  You can get ordinary UPS units on eBay, too, but they are typically very inexpensive and if you get one at the local computer store you save potentially significant shipping charges.
• If you get an ordinary UPS, you can tote it in your trunk.  The switchers weigh just a few pounds, the UPS units maybe 20 or 30.  This means that you can generate a KW at 115VAC without attaching anything to the 12V system in the Prius, without filling up your trunk, and without sacrificing mileage.  The switcher weighs so little that a permanent installation is in order; the UPS can be plugged in when needed. 
• If you need more than a KW, just get another switcher and another UPS.  Or three.  Or even more!  My caveat about only taking 3KW continuously applies to stationary operation.    If the hardware is in the trunk and you are driving, you can probably take even more than 3kW since there is now forced air ventilation to solve any thermal problems and two generators to recharge the Prius traction battery.

Here are practical examples of portable, working PriUPS systems.  You can too take it with you.

Here is additional information on the switching supplies I have found to be suitable.