Mobile/custom DC power supply and eliminating wall warts?

Discussion in 'General Electronics Chat' started by SpaceCaptain, Mar 27, 2016.

  1. SpaceCaptain

    Thread Starter New Member

    Mar 24, 2016

    I searched existing threads and did not find exactly what I was looking for, so i'll apologize beforehand if the question has been asked already.

    I would like to build a 5v-12v DC power supply and custom wire/power all of the small DC boxes with regulated power and lose all of the wall warts and heavy ac/dc power supplies that come with everything. The devices I have to power are a mixture of 12v 0.6a - 12.5a and 5v 0.5a - 4a. I do not know enough fundamentals to know where to begin. I assume my base will be an ATX power supply to a terminal block with individual inline fuses. Where should i begin and is there a smarter method of obtaining clean regulated DC power to cut out all the power blocks?

    I do alot of computing work and data work in a mobile system and I use a UPS (simulated sine wave) to protect external hard drives, however when having to work out of a car my UPS unit (Cyberpower) does not accept the "120v" coming out of the car, nor does it accept a 120v inverter. What is the fundamental reason this does not work and is there a safe way to power a UPS system from a car's alternator or similar inverter? The system's total draw is no more than 300W AC on the UPS unit, and it all gets converted to DC power anyway to power a laptop, misc 12v boxes, and external HDD's.
    Will the aforementioned DC power setup be a viable solution to power an entire system? Is it possible to have DC power on a battery backup system?

    A product called Meon Life is a rack mounted, 12v power and battery system to the effect of what im describing. Albeit, im looking to make one from scratch to power specific 12v / 5v devices, for significantly less.
  2. MrChips


    Oct 2, 2009
    You could try something along these lines:
    1. 12-15VDC to 12VDC buck/boost switching supply.
    2. 12-15VDC to 5VDC buck switching supply.
    3. 120VAC to 15VDC unregulated DC supply (aka - a battery charger).
    These three units together should satisfy all your needs as you described.

    Others may have different opinions.
  3. InspectorGadget

    Active Member

    Nov 5, 2010
    That Meon LiFe is a system for stage wireless audio systems, for direct power of the base units and charging of the remote units (mics, etc). It has an internal battery that takes over if mains power is interrupted.

    Context is everything. List the devices you simultaneously want to power. on 12V and 5V.

    Like, what in today's world could take 12A at 12V? 12A at 12V is not that easy to come by.

    Note: I've never seen a mobile UPS. Laptops have their own UPS -- their internal battery. So how often do you run external self-powered hard drives in the car? And how many?

    That being said, I googled "mobile UPS" and found this 12V UPS. Only 3A though. But you know, you should really try Google.

    For indoor use, here's a good 12V 7A + 5V 4A switching power supply.

    Those should be good enough leads... Think hard about how many 12V and how many 5V devices you're going to want to power simultaneously at home and in the car. Going overboard with the current requirements is going to cost you a lot of money and you may find with thoughtful analysis that you can really live with a lot less.

    But give us more details and we can have a discussion about it.
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    Whats wrong with using an Atx psu, 3, 5, 12v @22amp.?
  5. SpaceCaptain

    Thread Starter New Member

    Mar 24, 2016
    Thats a very good start, thanks MrChips i'll look into those

    Very informative, thanks. You're right perhaps if i elaborate more it will help. I'm a broadcast/camera technician and in a nutshell, i build a computer/video system for data management and color manipulation/correction. At its most basic, my large system is a mac pro (cylinder) connected to a bunch of DC video boxes, SSD raid's, and video distribution. I also run my client's HDD's thru this system which are typically two Glyph studio raids (for a total of 3-4 raids, or 8-10 physical disks, 4 of which are spinning drives). All connected to a UPS system, of which i own/use many but for sake of evaluation, lets call it this one on "average"

    I also run a "more mobile" system which is essentially the same thing but centered around a macbook pro as the computing base. This obviously uses only 85w and has its own internal battery but i do count it into the "paper load" of the system, as i'll have to keep it charged constantly anyway, albeit not constant. I'd like to find a solution for both systems, so id call it a load max of 300w.

    Still I'm a bit stumped at the fundamental question: Why doesn't this work with a car inverter/alternator when there is sufficient wattage present?
    Realistically, i don't need a massive power capacity and long runtime. I do need to be able to run my raids from the back of an SUV in a protected and battery "backed-up" situation to prevent data corruption/loss in a power spike or failure.
    I am also becoming aware that the variety of voltage and amperage might make a singular solution complicated, here is a summary of what is being considered
    12v 12a output
    BMD smart videohub

    12v 1.5a output
    BMD HDlink (2x)

    12v 5a output
    Caldigit TS2

    5v 4a output
    misc USB hubs

    I didn't refer to a "mobile ups", I have seen those batteries feel that at best they are a component for a possible solution, but by no means a good place to start. My primary goal is to shave off weight with all the AC/DC blocks and find a way to make this work in a car situation as well.

    I realize that it may be a huge endeavor to replace all existing power supply units with a singular one when the voltage and amperage ranges so much. The 5v stuff is all USB hub/expansion and it may be an easier solution to repurchase them in 12v input variety and stick with an all 12v system.

    I am open to your thoughts and suggestions here, thanks for the insight.
  6. InspectorGadget

    Active Member

    Nov 5, 2010
    Sorry about the delay.

    The car inverters don't put out a real sine wave. Most UPS units will detect ANY waveform irregularities as excessive noise or spikes and switch into battery mode, which I believe you observed already. If you find a "pure" sine wave inverter, it may work with the UPS. But why even try?

    As you said, you intend to "shave off weight with all the AC/DC blocks and ... make this work in a car". I think the "mobile UPS" is the perfect place to start. It gives you perfect, filtered, surge-protected, battery-backed-up 12V, which you can use directly for your 12V devices. You just need one with a big enough capacity to supply the 12A "videohub".

    Then for your 5V devices, you need some 5V Buck Regulators, what they call "DC-DC converters" in the catalogs. Here's an example of one that gives you 5V at up to 15A. You connect the inputs of these to the outputs of one or more of the 12V "mobile UPS".

    Are you sure that videohub takes 15A at 12V? Or was it 15A at 110 or 220V? 15A at 12V would have to be supplied with big, 14-gauge or 12-gauge wires!
    SpaceCaptain likes this.
  7. SpaceCaptain

    Thread Starter New Member

    Mar 24, 2016
    Inspector, thanks for the very informed reply. I think i had a fundamental misunderstanding of how the UPS worked. I assumed being a simulated sine wave, it took accepted "bad" or "dirty" power and conditioned it.
    I should also have mentioned that these two tasks I am looking to achieve, although great together, are separate endeavors for different equipment applications. For all intensive purposes, the mobile system that needs to run also set up on a table and run off regular home/commercial 120ac.
    I think you hit the nail on the head, the most immediate solution to work in a car is a pure sine inverter, i just hope i can get one shipped in time to travel again.
    In the meanwhile I will look into a mobile ups or building one with the batteries you mentioned, i do agree that going straight to 12v for the pehipherals is the smarter more efficient choice in the long run.

    It seems that I also misunderstood how to read amerage, as i just copied the power rating off all the wall warts and did not understand that the device will draw what power it needs up to the PSU limit, and the PSU generally will supply more than what the device needs by default, therefore whats printed on the PSU isnt always accurate.
    It actually looks like the big unit im looking to replace is 12v12a.

    Thank you again. very helpful.
  8. InspectorGadget

    Active Member

    Nov 5, 2010
    If you're going to get the "pure" sine wave inverter to use with a UPS, I would get it from somewhere that takes returns because what they consider "pure" and what the UPS considers "pure" may be two different things and it may still trip the UPS. I have my doubts but it's worth a try if you can return it.

    The nice thing about the mobile (12V) UPS (battery system) is that you can power the whole thing from a high-current 12V switching supply when you're set up at your table. And it's far less bulk and cost than the inverter/UPS and far more efficient in terms of power conversion losses.

    OK the 12A makes sense. Just wouldn't click for me at first for some reason.