Individual DC-to-DC voltage converter for small loads

[Veloc]

Rather than wiring out separate circuits for different voltages, I would suggest wiring everything house-related as 120VAC, and use a standard wall-wart to power low voltage/DC items. Is it the most efficient this way? Probably not, but it simplifies the internal wiring, makes troubleshooting future problems easier and allows all plugs to be used for all things. You can split heavy load items to use their own inverters off the batteries, so they can be shut down when not in use, and use an inverter to power all the little things like your cell charger and TV and whatnot. For the weight of the extra wiring and components you can just slop in another battery or two to make up for the small loss of efficiency converting from 120VAC to XXVDC. Plus, later on down the road when you no longer have that weird voltage item, the wiring you put in just for it becomes useless weight.

[TaliaDPerkins]

" using an amplifier IC and some smoothing caps "


Class D amplifier and inductor as well, I suggest.

[Booyah45828]

Originally Posted by Veloc

Rather than wiring out separate circuits for different voltages, I would suggest wiring everything house-related as 120VAC, and use a standard wall-wart to power low voltage/DC items. Is it the most efficient this way? Probably not, but it simplifies the internal wiring, makes troubleshooting future problems easier and allows all plugs to be used for all things. You can split heavy load items to use their own inverters off the batteries, so they can be shut down when not in use, and use an inverter to power all the little things like your cell charger and TV and whatnot. For the weight of the extra wiring and components you can just slop in another battery or two to make up for the small loss of efficiency converting from 120VAC to XXVDC. Plus, later on down the road when you no longer have that weird voltage item, the wiring you put in just for it becomes useless weight.

That's what I would suggest as well.

From an efficiency standpoint, it's best to have your battery voltage match the native voltage of the DC devices. No conversion means no conversion losses.

The problem is doing such a thing can get expensive, especially if the hardware isn't common or made for longevity. You can buy 12vdc-120vac inverters at a number of places for cheap. I'd stick with cheap and common with a little inefficiency, unless I can guarantee the uncommon units will last for years in service.

[HamSkoolie]

The problem with using battery voltage of end use devices is that you're going to end up with a 12 volt battery bank and 12 volt wiring. A given wire size carries HALF the current at 12 volts as at 24 and a QUARTER of the current of a 48 volt system.
In a 40 foot bus you'll be running 12 volts fairly long distances for a good number of DC circuits thus suffering voltage loss in each line as well as a thinner pocketbook to pay for all that extra copper.
Why not run a 24 or 48 volt battery bank with large short cables to the inverter for 110-120 needs and then a 24 or 48 volt "main" line to several "regional" DC-DC converters which then supply 12 volts to regional fuse blocks with the small wires emanating from those regional (thus much shorter) blocks? We will be running a 6ga 48 volt main line to at least 3 regional fuse blocks. Since all of our 12 volt needs will be low amp draws we will then be able to use smaller wires to the end use point.

Here are some calculated differences (remember, you'll be snaking wires around things most of the time so distance is usually much larger than the straight line distance).

5a, 15' (one way), allowing 3% voltage drop is
12 volt 12ga
24 volt 16ga
36 volt 17ga (so still using 16ga)
48 volt 18ga

Now, if for this example we assume that there is a 12 volt battery bank and we're running the entire circuit but with 10 feet between the battery and regional fuse block, the wire sizes change to:
12 volt 10ga
24 volt 13ga (effectively 12ga)
36 volt 15ga (effectively 14ga)
48 volt 16ga

Smaller wires are cheaper to buy though you do need additional step down converters and fuse boxes. But the main benefits are reduced wire VOLUME and simplification of troubleshooting as if an item loses power and anything on the block it comes from has power it's the fuse or short run to the inoperative item rather than all the way from the battery or fuse block at the battery.
Just MY opinion. I'm a Marine so that H word isn't in my vocabulary. L()L

[rv8flyboy]

I have done the same thing, up convert my 12 volt to higher voltages on incidental loads.

Suggesting you rewire yer bus to 30 volts because you have one device that has an oddball voltage is impractical.

Just find a properly rated, good quality, dc to dc converter, make sure your on/off switch is before the converter, 12v side, as the converter will continue to suck energy even with no load.

Using a wallwart isnt always practical as it requires running an inverter to go from 12 v dc to 110 v ac to go back down to whatever dc volt needed. Sometimes just having a small dc to dc converter makes more sense,

Just buy a quality one, not a cheep scAmazon one, although the one in the picture shown i have used with good success, at a similar looking one.

Make sure u buy one with a common rail negative, saves a lot of headaches, not all inverters are common rail negative!! This means negative on 12v side is connected to negative on output side.