How can I run a desktop off a battery?

[Okjoek]

I'd love to try this sort of "off the grid" project involving making a low power desktop with a part like AMD's upcoming 65w Raven Ridge APU.

 

My electronics knowledge is limited to the basic and digital electronics course I took in HS.

Is there a way to convert the DC of a battery bank to the AC outlet that plugs into a desktop's PSU?

[Godlygamer23]

You can use an Uninterruptible Power Supply. 

[Crunchy Dragon]

Just now, Godlygamer23 said:

You can use an Uninterruptible Power Supply. 

Or that huge battery Linus had in that one episode of Holy Sh!t

[AlTech]

2 minutes ago, Crunchy Dragon said:

Or that huge battery Linus had in that one episode of Holy Sh!t

That is what Godly is taking about.

 

A UPS is pretty much a huge battery.

[AkiraDaarkst]

6 minutes ago, Okjoek said:

I'd love to try this sort of "off the grid" project involving making a low power desktop with a part like AMD's upcoming 65w Raven Ridge APU.

 

My electronics knowledge is limited to the basic and digital electronics course I took in HS.

Is there a way to convert the DC of a battery bank to the AC outlet that plugs into a desktop's PSU?

You basically need a power inverter to convert DC to AC, and of course the electrical setup needs to output the correct stabilized voltage.  In some developing countries, I've seen people use huge acid batteries with inverters to power their homes/appliances because the country/city/village doesn't have reliable electrical grid systems.

 

When I travel, I even have a small inverter in the car that uses the car's battery (via the cigarette lighter port) to power my cameras and other devices.

[Crunchy Dragon]

1 minute ago, AluminiumTech said:

That is what Godly is taking about.

 

A UPS is pretty much a huge battery.

I know what a UPS is, I was just mentioning it.

[brob]

5 minutes ago, Okjoek said:

I'd love to try this sort of "off the grid" project involving making a low power desktop with a part like AMD's upcoming 65w Raven Ridge APU.

 

My electronics knowledge is limited to the basic and digital electronics course I took in HS.

Is there a way to convert the DC of a battery bank to the AC outlet that plugs into a desktop's PSU?

There is, but one can also get DC-DC psu. Thin mini-ITX motherboards generally take DC power.

[Bananasplit_00]

uuu yah dont bother doing that lol, that would be way less efficient than a straight DC-DC PSU for it  

[Mira Yurizaki]

You can use an inverter off a car battery as suggested, or you can find a way to make 12V, 5V, and 3.3V and wire it up to the necessary power connectors on the motherboard.

 

Or you can hope AMD will try this hands on something like the NUC. The NUC takes in DC, so all you'd have to do then is get a DC-DC converter.

[Blebekblebek]

Solar panel with battery, specially tesla battery is the most effective for this purpose.

 

However I don't see this viable enough in small scale, it just to expensive to maintain, you have to charge your battery afterall.

[Godlygamer23]

1 hour ago, brob said:

There is, but one can also get DC-DC psu. Thin mini-ITX motherboards generally take DC power.

They all take DC power. Power supplies convert power from AC to DC coming from the wall. All PC components use DC power.

[brob]

22 minutes ago, Godlygamer23 said:

They all take DC power. Power supplies convert power from AC to DC coming from the wall. All PC components use DC power.

I don't get your point. In order to easily convert a single DC-in line into the appropriate voltages for a PC system, one needs a DC-DC psu.

 

Thin mini-ITX motherboards are usually designed to take a single 19V DC input (from a power brick). The motherboard takes care of splitting that up into voltages appropriate for its components. Often the motherboard will include a SATA power connector.

[Godlygamer23]

1 hour ago, brob said:

I don't get your point. In order to easily convert a single DC-in line into the appropriate voltages for a PC system, one needs a DC-DC psu.

 

Thin mini-ITX motherboards are usually designed to take a single 19V DC input (from a power brick). The motherboard takes care of splitting that up into voltages appropriate for its components. Often the motherboard will include a SATA power connector.

Your statement was that they generally take DC power.

 

All PCs use DC power. In a standard PC, you have an AC to DC power supply. Power coming from the wall is AC, power going to the PC is DC. No PC uses AC power.

[brob]

Just now, Godlygamer23 said:

Your statement was that they generally take DC power.

 

All PCs use DC power. In a standard PC, you have an AC to DC power supply. Power coming from the wall is AC, power going to the PC is DC. No PC uses AC power.

I guess I was not clear enough. Thin mini-ITX motherboards take a SINGLE DC power input. Other ATX/ITX motherboards require multiple voltages in.

[mariushm]

You typically convert a DC voltage to AC using a device called POWER INVERTER

 

A power inverter takes some DC voltage (let's say 10v .. 14v , typical for a lead acid battery used in cars, but there are 24v power inverters, made for trucks usually) and converts it to AC voltage, 110v or 220v being two typical values.

Modern computer power supplies will accept a wide range of input voltages, let's say 90v to 250v AC so whatever power inverter you decide to use, it should work.

 

This is not ideal, because you're taking low DC voltage and you boost it up to a higher AC voltage which means there's some power losses (heat in the power inverter) and then the power supply has to take this high AC voltage and convert it back down to the DC low voltages used by computers (12v , 5v and 3.3v) adding another bit of losses to the process.

 

There are some motherboards which are designed to work directly from a DC In jack, from a voltage between 16.5 and 19v. These motherboards have all the circuitry on them to convert this voltage (common in laptop power adapters) down to 12v, 5v and 3.3v

You could buy such a motherboard and , instead of using a AC laptop adapter to produce this 19v required by the motherboard, you could buy a commercial power supply that takes battery voltage (let's say 10v .. 14v) and boosts this voltage up to 19v and the motherboard will be happy. 

 

Here's just two examples of motherboards which have a DC In jack :

 

1. ASUS N3050T Intel Celeron Dual-Core N3050 SoC onboard Processors Thin Mini-ITX Motherboard/CPU/VGA Combo : https://www.newegg.com/Product/Product.aspx?Item=N82E16813132732&ignorebbr=1

Some slightly less common DC In jack - i think it's the one usually found in HP laptop adapters - but it's some standard  voltage

 

2. ASRock J3160DC-ITX https://www.newegg.com/Product/Product.aspx?Item=N82E16813157714&ignorebbr=1

Standard 5.5mm  OuterDiameter  2.1mm (or 2.5mm InnerDiameter, i don't remember exactly, it says in manual)

 

Asrock has some AMD boards as well with DC In connector but can't find one on Newegg right now, too lazy to look in other places.

 

edit: so instead of using an ac laptop adapter to produce this 16.5v to 19v, you can buy a separate power supply that would accept 10..14v and produce 16.5v to 19v and this way you can power your computer by using only one more efficient conversion (up to 92-95% efficient compared to 70-85% with inverters), from the smaller voltage to (up to) 19v.  

 

Here's an example :

 

16.7$ : GE Critical Power, 9.6v to 14.4v input voltage, output voltage configurable between 16v and 34v , up to 65 watts, up to 94% efficient

 

 

If you don't get a motherboard with such a DC In jack, there are some tiny power supplies which take in some DC voltage and produce the 3 voltages required by PCs.

They're not GREAT power supplies, but they're good if the computer doesn't use lots of power (let's say less than 50-60w, at most a Ryzen 3 1200 but even that would be a bit pushing it)

Here's some examples:

 

M2-ATX 160w , 6v to 24v input : http://www.mini-box.com/M2-ATX-160w-Intelligent-Automotive-DC-DC-Power-Supply?sc=8&category=981

M4-ATX  250w psu, 6v to 30v input : http://www.mini-box.com/M4-ATX?sc=8&category=981

 

You can find cheaper models here : http://www.mini-box.com/DC-DC but those cheaper models are designed with the expectation that you'll power them with 12v that's regulated, for example from a 12v laptop adapter. They basically pass through the input voltage to the 12v pins on the power supply (which goes to power fans and cpu and video card), so they won't work well if you power them from a 12v battery because the voltage on such a battery will vary a lot, between around 10v to 13-14v ... and you can damage computer components if the voltage is higher than around 12.8v

Anyway, these tiny power supplies can be quite efficient, up to 90-95% so you'll get much longer battery life if you'd power the computer directly from battery with one of these.

 

You'd have around 85% efficiency converting from DC to AC with a power inverter, then a regular desktop power supply will only be around 75-80% efficient when converting down from 110-230v back to 12v and 5v and 3.3v