computer that runs directly from DC current

I'm building a solar powered shop with battery storage. While some of my motors will require 120/240 volts from an inverter, the stepping motors can be powered directly from the batteries.
Does anyone know of a computer that will run LinuxCNC, that can be powered directly from batteries and bootable from micro SD card? If I convert to 110 and run it through a power supply to get back down to 12 and 5 volts, I lose power during both conversions. An SD card would draw less energy than a hard drive.
While I know laptops run off batteries, they're usually an odd voltage, not a multiple of 12.
One of my spindles is powered by a VFD so I hope there's a DC version of it as well.

Raspberry Pi 3 I think is perfect for your project, though there are many more very low power consumption modules out there that is programmable and everything is built in such as ESP8266

I'm not sure there is an officially supported Raspberry PI version of LinuxCNC. Perhaps the MachineKit derivative? If you want to stick with the mainline LinuxCNC, the cheapest solution if you already have a somewhat low power PC is to get a PSU that runs straight from 12VDC. For an example, take a look at a picoPSU:

picoPSU-120 12V DC-DC ATX power supply

That one takes 12VDC in, is good for 120 watts, and runs about $35. They make other ones for higher or lower wattages and different voltages as well.

If you are looking for a lower power PC, a small industrial fanless type PC might work for you. I got a J1900 based system off of aliexpress which has dual ethernet ports (one for external network and one for a Mesa 7i92) that uses less than 60 watts of power. I haven't tested the power usage but it only comes with a 60 watt power supply so that is a max. The PC with a 30GB mSATA SSD was $134 and I added an 8GB stick of RAM for another $52. The SSD should have substantially less current draw than a hard drive but may not be quite as low as an SD card. mSATA should be much faster than an SD card though. Here is the one I got:

https://www.aliexpress.com/item/XCY-...311.0.0.6fXCMK

I installed Linux Mint and had to build a kernel and LinuxCNC to support the user mode necessary to support the ethernet based 7i92 card.

There are various options if you don't mind building the system. Using the above mentioned PSU with a low power mini-itx sized motherboard with an mSATA drive would work well and be reasonably low power with the right CPU. Some motherboards directly support a single DC supply but those tend to be more expensive.

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Originally Posted by Goosey

One of my spindles is powered by a VFD so I hope there's a DC version of it as well.

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All VFDs run on DC and it is possible to feed them with DC. They convert the incoming AC to DC internally, then they magically convert the DC to 3 phase AC out. The problem you might have is the DC bus in the VFD runs at about 320 volts for a 230 volt VFD.

I'm running mach4 on a lattepanda alpha. It accepts a 12v DC input.

Sent from my LM-G820 using Tapatalk

Do an ebay search for "Intel NUC", and you'll find plenty of little single boards that run off of DC.

You can use the PicoPSU gizmo to power a standard ATX motherboard from a 12VDC supply.

https://www.mini-box.com/core/media/...ntrGmvvZTYkABV