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need 48vdc to 12 vdc converter
By iFred, Section Controls Posted on Wed Jun 22nd, 2005 at 07:10:30 PM MST
for solar system

I'm looking for a 48vdc to 12 vdc converter. (around 1000watt or less) wondering if anyone has circuit for it. I checked the web but did'nt find much. Thanks in advance.

need 48vdc to 12 vdc converter | 14 comments (14 topical, 0 editorial)

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#1)
by terry5732 on Wed Jun 22nd, 2005 at 03:44:51 PM MST
(User Info)

Conversion is lossy by nature. You must be able to reconfigure array for 12 volt output! Just parallel wire 12 volt segments.

Divide and conquor - or is that concher? (3.00 / 0) (#2)
by wdyasq on Wed Jun 22nd, 2005 at 04:53:38 PM MST
(User Info)

It seems to me a proper divider would be made with four capacitors and some switching. One might need a pair of these to charge/discharge properly. It woould seem to be fairly effiecint and the opposite of a voltage "doubler" or really, a quadupler.

Ron
Adventure is just bad planning." -- Roald Amundsen

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#3)
by drdongle (Dr.Dongle1@juno.com) on Wed Jun 22nd, 2005 at 05:25:02 PM MST
(User Info)

48 to 12 volt DC to DC converters are fairly common, though 1KW is a bit on the high side. All Electronics ( www.allelectronics.com)has a unit Cat# PS-526 $19.00 ea, that may get you started the output for 12 volts is 10 amps so use 8 or 9 of them for multiple loads. You also get +5 at 25 amps and -12 at 1 amp this would also be good for an older PC to run off 48 V.
I have one and it seems that the connections were well labeled.
Carpe Vigor, Dr.D

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#4)
by commanda (alwynne at unwired dot com dot au) on Thu Jun 23rd, 2005 at 03:28:51 AM MST
(User Info)

The cheaper voltage reducers are usually linear regulators. Current in = current out. If 48 volts in & 12 volts out, 3/4 of your energy is being dissipated in heat.

If it's got heatsink fins all over the outside, it is one of these.

Probably not much use to you, as shipping costs would kill you. Oatley electronics here in Australia have ex-telecoms switchmode supplies. 48 volts in & 24 volts out. 1Kw. The output can be changed to 12 volts fairly easily. They include a circuit diagram & instructions on how to modify (change a couple of resistors).

These supplies are used all over the world. Digging one up locally is a challenge I leave you to pursue.

Amanda

[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#7)
by joelhacker (joel dot hacker at motorola dot com) on Thu Jun 23rd, 2005 at 10:50:43 AM MST
(User Info)

If you are going to run multiple converters in parallel, you must use
resistors on the output of each side of the positive terminal so small
differences in their regulators don't drive eachother batty and one
regulator which is tweaked for a slightly higher voltage doesn't wind
up trying to pull up the other converters while their regulators tries
to pull the high one down, and slowly one-by-one your bank of converters
kills each other off (of at least constantly blowing all the fuses).

[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#9)
by drdongle (Dr.Dongle1@juno.com) on Thu Jun 23rd, 2005 at 06:47:31 PM MST
(User Info)

I just got the latest Astrodyne catalog ( www.astrodyne.com, 800 823 8082 ) their model SD350C-12 is 350 watts (27.5 A @12V out) price is $129.00 in small quantities, you would only need three of these.
Carpe Vigor, Dr.D
[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#5)
by iFred (ifred2006@yahoo.com) on Thu Jun 23rd, 2005 at 08:46:42 AM MST
(User Info)

Thank you for your comments and suggestions.

The issue at hand was decreasing IR transmission losses . I can hook up the panels in any orientation 12-24-48 as well as the batts, the question came down to prices. when I checked out the prices for 24 and 48 vdc to 110vac inverters, these are 3 to 4 times the price or more of a 12vdc system. So I figured that if I could use passive components (non-linear) and reduce the voltage after the fact and feed that to the inverter, I could use a standard 12vdc inverters that I have, thus reduced IR line loss and still maintain a better system. Seems I may have to build one, but was hoping someone may have a circuit available.

Here is the basic idea.

http://www.powerdesigners.com/InfoWeb/design_center/articles/DC-DC/converter.shtm

>> all energy used to produce this comment or post came from solar and wind energy! It works!

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#8)
by joelhacker (joel dot hacker at motorola dot com) on Thu Jun 23rd, 2005 at 11:14:22 AM MST
(User Info)

Just remember by Ohm's power law, and that you would be
switching ~25V AMPS @ 48 Volt DC if your transistor were
on all the time to get 1kW. However, since your switching
is on and off, then your power increases as your duty cycle
(avg time on/avg time off) decreases.

Your transistor(s) must be able to handle the current involved
in this type of switching.

Also, remember, that you will have a ripple voltage which
will be dependent upon the size of your capacitor, your inductor.

[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#12)
by georgeodjungle (georgeodjungle@hotmail.com) on Thu Jun 23rd, 2005 at 11:07:00 PM MST
(User Info) http://www.serveingplumas.20fr.com

bigger wire = 0 line loss
that's it.

[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#6)
by ghurd on Thu Jun 23rd, 2005 at 09:01:59 AM MST
(User Info)

There is a line of chips you may want to look at.
'Simple Switcher' should bring up some good info.
G-

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#10)
by georgeodjungle (georgeodjungle@hotmail.com) on Thu Jun 23rd, 2005 at 10:25:26 PM MST
(User Info) http://www.serveingplumas.20fr.com

what are ya converting?
wind genny, alt, charger?

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#11)
by georgeodjungle (georgeodjungle@hotmail.com) on Thu Jun 23rd, 2005 at 10:56:53 PM MST
(User Info) http://www.serveingplumas.20fr.com

ops.
just read the hole thing.
here is the thing.
my inveter, trace 5512rv.
and others out there, all so run on 12 or 24v with NO mods.just change the sticker.
just read the directions.but cost more? i don't get that part.
or a switch "jumper" inside.
even some of the cheep ones from horbor frieght & hartland.
over 2kw that is. maybe for big trucks ?
make shure! don't blow up your new inverter!
not all of-em do that.
so all that said, i'd think there's got to be an easy way to get to 48?
get 2 or 4 little ones & stack-em? the input side, that is.
has any one tried that?

[ Parent ]

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#13)
by ignesandros (ignesandrosATgmailDOTcom) on Sat Jun 25th, 2005 at 06:37:44 PM MST
(User Info)

Transformer?

Re: need 48vdc to 12 vdc converter (3.00 / 0) (#14)
by commanda (alwynne at unwired dot com dot au) on Sun Jun 26th, 2005 at 03:40:00 AM MST
(User Info)

Transformers only work on AC, not DC.

Amanda

[ Parent ]

need 48vdc to 12 vdc converter | 14 comments (14 topical, 0 editorial)

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