need 48vdc to 12 vdc converter

[iFred]

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.

[terry5732]

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

[wdyasq]

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

[drdongle]

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.

[commanda]

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

[iFred]

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

[ghurd]

There is a line of chips you may want to look at.

'Simple Switcher' should bring up some good info.

G-

[joelhacker]

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).

[joelhacker]

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.

[drdongle]

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.

[georgeodjungle]

what are ya converting?

wind genny, alt, charger?

[georgeodjungle]

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?

[georgeodjungle]

bigger wire = 0 line loss

that's it.

[ignesandros]

Transformer?

[commanda]

Transformers only work on AC, not DC.

Amanda