Suggestion for DC power office

[ct7ahv]

Why 400W? You can get AIO (all-in-one) desktops that run on 12Vdc (some at 19Vdc) - and many come with 23" displays.

I'm currently on a Lenovo laptop WO/its display, feeding a 27" 4k LG monitor that prefers 19Vdc.

400W is the estimated peak power DC each computer consumes.
Is possible to install 6 HDD 3.5” on an AIO?
I use several PCIe boards for peripherical devices and I can’t install them on an AIO…
Also, It will be hard to find AIOs with half performance of these desktops… and if I find they will not be cheap!

 

[ct7ahv]

13.6v is high enough to fully charge newer healthy lead acid batteries, it just takes a lot longer.

In daily or deep cycle service, it is best to get them to, and hold them at absorption voltage until amperage tapers to 0.5 amps per 100ah or rated capacity at 20 hour rate.

Getting that last few % into lead acid will make a huge difference in their cycle life.

As lead acid ages, it takes longer and longer to get that last 10% in, and the rate of degradation increases sharply of they do not get to spend enough time at manufacturer recommended, temperature compensated aborption voltage.

I added fingertwist voltage adjustability to all my 12v power supplies, and Ammeters!

See how much goies to loads, how much goes.into battery

Thank you for your sharing!
I built two 100A ammeters, each one with the hall sensor ACS756-100. The sensors give me a voltage output proportional to current. I’m doing a healthy brainstorm, I can make a circuit with solid state relays to switch between power supply and MPPT controller based on voltage drop and current demand. What do you think?

 

[fechter]

The battery will be able to handle very large currents for short durations. The power supply really only needs to supply a little more than the average current.
A computer won't take anywhere near the peak power of its supply rating most of the time. You can measure it.
You could have a voltage monitor on the battery that triggers a relay to kick in the power supply at a certain voltage. I think the solar part could stay connected all the time.

 

[amberwolf]

I have chargers to use on cars’ batteries and they produce noise.

Which specific charger? Some of those use a kind of switch (sometimes a kind of circuit breaker) to automaticlaly turn the output on and off, and this can cause significant RF noise when it cuts off under load from the arcing. So the noise happens only in bursts.

Some don't even have a transformer, what are often called Bad Boy chargers, and just directly connect mains power to the car's lead acid battery, in bursts, thru a big diode (usually not even a full bridge), and those can make a lot of noise but not usually in RF (unless they have the autoswitch like the above).

Some are SMPS, and many of those designs make a lot of RF, some of which can be shielded out but some of which may not be preventable without altering the design.

Some are just regular transformers and full or half bridge rectifiers, with or without capacitors, and those don't usually make RF bu tthey can make a lot of audible 60hz noise from the transformer vibration whenever current is high.

 

[amberwolf]

Is possible to install 6 HDD 3.5” on an AIO?
I use several PCIe boards for peripherical devices and I can’t install them on an AIO…

Perhaps not internally, but you can use external devices for both of those situations. Some of the external PCIE units connect to an internal PCIE slot, or an NVME slot, some of them use USB3, etc.

Plenty of external USB (2, 3, etc) options for HDDs of all types and sizes. If the USB3 host port correctly supports USB3 power demands, they can be powered from that. If not, they'll need external power, all of which can be made to work from 12v with the proper DC-DC.

 

[amberwolf]

I have two desktop computers with ATX power supplies and they receive 100 to 240VAC.
Does anyone know where I can get ATX power supplies, at least with 400W, without have to sell the liver to purchase them?

I know Powerstream makes 12V DC input ATX (and other form factors) PSUs that can handle at least that much power. (I have a pair of them that are the 48V input version here somewhere). Don't know what they cost new, but I bet you can get them used out of old machines cheaply enough if you poke around; these things have been around for decades.

Their page for it:

12V DC Input PC ATX 400W Power Supplies 140mm PS2, Autonomous vehicle computer power supply 12 volt Input, 400 watts.

12 volt DC Input,12 volt to ATX 300W Computer Power Supply.

www.powerstream.com

I'm sure there's other manufacturers too.

 

[ct7ahv]

The battery will be able to handle very large currents for short durations. The power supply really only needs to supply a little more than the average current.
A computer won't take anywhere near the peak power of its supply rating most of the time. You can measure it.
You could have a voltage monitor on the battery that triggers a relay to kick in the power supply at a certain voltage. I think the solar part could stay connected all the time.

That's it, will be the way to go! Thank you! Now I'm looking for a nice power supply...

 

[ct7ahv]

Which specific charger? Some of those use a kind of switch (sometimes a kind of circuit breaker) to automaticlaly turn the output on and off, and this can cause significant RF noise when it cuts off under load from the arcing. So the noise happens only in bursts.

Some don't even have a transformer, what are often called Bad Boy chargers, and just directly connect mains power to the car's lead acid battery, in bursts, thru a big diode (usually not even a full bridge), and those can make a lot of noise but not usually in RF (unless they have the autoswitch like the above).

Some are SMPS, and many of those designs make a lot of RF, some of which can be shielded out but some of which may not be preventable without altering the design.

Some are just regular transformers and full or half bridge rectifiers, with or without capacitors, and those don't usually make RF bu tthey can make a lot of audible 60hz noise from the transformer vibration whenever current is high.

The two battery chargers I have to use on vehicles are cheap ones, they have SMPS and a charge controller. I only use them when I need to charge the battery of one of my cars so it is rare to use the chargers...

 

[ct7ahv]

Perhaps not internally, but you can use external devices for both of those situations. Some of the external PCIE units connect to an internal PCIE slot, or an NVME slot, some of them use USB3, etc.

Plenty of external USB (2, 3, etc) options for HDDs of all types and sizes. If the USB3 host port correctly supports USB3 power demands, they can be powered from that. If not, they'll need external power, all of which can be made to work from 12v with the proper DC-DC.

An AIO computer is not suitable for my needs. I run server services on these computers, HDDs configured in RAID, SFP+ network cards... Remove the HDDs and put inside enclosures with USB will make a bottleneck in the system and certain SMART technology doesn't work under USB discs, as well as PERC controllers from Dell. I have an iMac that is an AIO and as machine is not versatile.

 

[ct7ahv]

I know Powerstream makes 12V DC input ATX (and other form factors) PSUs that can handle at least that much power. (I have a pair of them that are the 48V input version here somewhere). Don't know what they cost new, but I bet you can get them used out of old machines cheaply enough if you poke around; these things have been around for decades.

Their page for it:

12V DC Input PC ATX 400W Power Supplies 140mm PS2, Autonomous vehicle computer power supply 12 volt Input, 400 watts.

12 volt DC Input,12 volt to ATX 300W Computer Power Supply.

www.powerstream.com

I'm sure there's other manufacturers too.

Thank you for the suggestion, I will consider these power supplies from Powerstream!