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[aprssig] Prius Power for Field Day

Robert Bruninga bruninga at usna.edu
Fri Oct 12 22:28:15 UTC 2007


> 220VDC doesn't equal 220VAC.  Will the power supply handle DC
input?

Yes, almost all modern switching supplies first rectify to DC
before doing the power conversion. But they almost ALL use a
simple trick to run on 120 and 240.  For 240 VAC, it goes
straight to a bridge rectifier and so the supply will run on 240
VAC (or up to 350 VDC) (peak value of AC).  

But you cannot do this for 120 VDC.  Because they almost all
have that 120/240 VAC switch.  All it does is throw one of the
two input filter capacitors into the bridge rectifier to make it
into a voltage doubler at 60 Hz.  So even the 120 VAC becomes
about 300+ VDC for the switcher.  That switch is just a single
pole SPST switch to switch over one leg of the bridge rectifier
so that makes one of the capacitors become a voltage doubler.
(in side the Kewnood power supply it is just a jumper to remove
for 220  volt operation)/.

And, if you look at the schematic, this trick also lets the 300+
VDC split evenly over the two caps, so they can have a working
voltage of 200V or less since at 240 VAC (or up to 350 VDC) they
are in series.

So you can run almost any switching supply made for 120/240 VAC
straight from the Prius 220 VDC battery.  As long as you don't
mind voiding your warranty, blowing yourself up or killing
yourself messing where you shouldn't be messing...

The advantage of this over running off the 100 amp 12 volt DC/DC
supply built into the Prius, is that you can run the 220 VDC
hundreds of feet using normal protected #18 wire and convert
down to 12V DC and 20 amps at the radio.  Instead of only being
able to run a dozen feet or so using # 8 wire to get the same
power.

Bob

> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Robert
Bruninga
> Sent: Friday, October 12, 2007 1:31 PM
> To: 'TAPR APRS Mailing List'
> Subject: [aprssig] Prius Power for Field Day
> 
> Now that I see that the 12 volt power supply works on 240 VDC
> input, I can bring along a few of these to field day, and
power
> every tent's 12 VDC systems from the 220 VDC battery in my
> Prius.  And if the battery runs down to 40% depth of
discharge,
> then the Prius engine automatically starts re-charging it with
> its 10 kW generator. 
> 
> A whole lot quieter than those 120 dB generators that drone on
> all weekend!
> 
> Oh, and if the load is under 200 watts continuous and the sun
is
> shining, then my Prius internal combustion engine will not
even
> crank up.  Till the sun goes down...  See:
> 
> http://www.ew.usna.edu/~bruninga/APRS-SPHEV.html
> 
> Now I am working on 240 VDC connectors so that there is no
> possible way for anyone to plug in the wrong thing to the
DC...
> Oh, and lots of fuses everywhere...
> 
> Bob, WB4APR
> 
> > -----Original Message-----
> > From: aprssig-bounces at lists.tapr.org 
> > [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Robert
> Bruninga
> > Sent: Friday, October 12, 2007 2:58 PM
> > To: 'TAPR APRS Mailing List'
> > Subject: RE: [aprssig] Kenwood KPS-15 switching Power supply

> > in Europe?
> > 
> > Thanks,
> > I tried it on a low currrent bench supply and with the
jumper
> > removed, it started producing 13.8VDC with 160 volts on the
> > input.  I raised it to 240 VDC input and it was still doing
> > fine.  My smallest load was 1 amp on the output, but even
that
> > shut down the supply due to the 100 mA limit of my 240 VDC
> power
> > supply.
> > 
> > But I think you are right.  I even see now that the catalog
> > shows that supply is good for 120 or 240 even though there
is
> no
> > mention of that on the nameplate.
> > 
> > Oh and I load tested it at 120VAC input and at 21 amps it
was
> > down to under 10 volts.  So it does not produce the 23 amps
at
> > 13.8 that the nameplate suggests.
> > 
> > Thanks!
> > 
> > > -----Original Message-----
> > > From: aprssig-bounces at lists.tapr.org 
> > > [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Keith
> > VE7GDH
> > > Sent: Friday, October 12, 2007 2:44 PM
> > > To: aprssig at lists.tapr.org
> > > Subject: Re: [aprssig] Kenwood KPS-15 switching Power
supply
> 
> > > in Europe?
> > > 
> > > Bob WB4APR wrote...
> > > 
> > > > Does anyone in Europe with 220 mains use the Kenwood
> KPS-15
> > > > switching power supply? It is good for 23 amps at 120
VAC.
> > But
> > > > I see no nameplate indication that it can run from
220-240
> 
> > > and it does
> > > > not have the little voltage switch to select... I see
also
> 
> > > a yellow jumper
> > > > wire near the input caps that would seem to possibly be
> the 
> > > "switch"...
> > > 
> > > I don't have one, but I did a search and found a page at
> > > www.universal-radio.com/CATALOG/hamps/4273.html
> > > that indicates that "this power supply input may be
> converted
> > to
> > > 220 VAC input via an internal jumper cable." You might
want
> to
> > wait
> > > for a confirmation from somewhere else, but at a glance,
it 
> > > sounds like
> > > you have found the jumper.
> > > 
> > > 73 es cul - Keith VE7GDH
> > > --
> > > "I may be lost, but I know exactly where I am!"
> > > 
> > > 
> > > _______________________________________________
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> > > aprssig at lists.tapr.org
> > > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> > > 
> > 
> > 
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> > 
> 
> 
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