[Nut-upsuser] Supporting a DIY UPS with minimal effort butmaximum gain
Kelly Byrd
kbyrd at memcpy.com
Fri May 17 15:06:47 BST 2024
Re "DIY-NAS", that was a typo. I did mean "DIY-UPS" as you suspected.
Re: Using custom vid:pid while specifying the arduino subdriver, I didn't
know that! So if someone finds a particular board that doesn't match, they
could still move forward without needing to patch NUT. Nice!
On Fri, May 17, 2024 at 5:42 AM Jim Klimov <jimklimov+nut at gmail.com> wrote:
> Looks very great, thanks for writing this! I gather you'd port this to the
> Wiki page you've started, too?
>
> A couple of comments:
>
> > So I run a NUT server on a Raspberry PI which is connected via USB to my
> DIY-NAS Arduino.
>
> DIY-UPS?
>
> > See drivers/arduino-hid.c for the list of supported IDs...
>
> Since NUT v2.8.1 [PR #1369], the `usbhid-ups` driver allows the user to
> specify a `subdriver` in config - to use the specific mapping for the
> specified vendorid:productid (and/or other matching options involved),
> allowing for IDs not yet known to NUT (built into any driver) or to use a
> different subdriver than the one associated with those IDs (some vendors
> historically have same IDs used for significantly different products).
> Either way, while it is ideally preferable to test and post PRs with
> correct out-of-the-box detection of devices handled by this or that code,
> the specimens seen roaming in the wild keep eluding any pre-created
> matchers that are set in stone for the particular build of (packaged) NUT.
> This feature allows for at least some more tweaks and experiments in the
> field.
>
> Hope this helps,
> Jim Kl.imov
>
>
>
> On Fri, May 17, 2024 at 1:05 PM Kelly Byrd <kbyrd at memcpy.com> wrote:
>
>> Ha! I got several on and off list requests for details, so I'll give a
>> bunch of details here and then maybe I can move this to a wiki page others
>> can help edit.
>>
>> WARNING! WARNING! WARNING!
>> Be careful! My implementation required opening up high power components,
>> and dealing with 120VAC mains power and high currents on 12VDC. If you
>> decide to tackle any of this yourself, you need to understand how to do
>> this safely, size components appropriately, etc.
>>
>> My goal is to keep a home Internet connection available during a power
>> outage. This doesn't happen that often, but it bugged me when it did and I
>> like playing with power-related things, so this became a fun project to
>> tackle. I guess I should mention that my home network gear is in a rack in
>> the garage. "modem", router, switch, wifi APs powered over PoE from the
>> switch, NAS, and typically a Raspberry Pi or two doing whatever "always on"
>> things I want. I also previously built a substantial portable battery box
>> that will power other appliances like TVs and computers, but the networking
>> gear is all in the garage and I can't power both at once without some very
>> long extension cables snaking through the house.
>>
>> I noticed a few years ago that my Internet connection stayed up during a
>> couple of different neighborhood power outages, assuming I could power the
>> gear on my side. I guess the equipment on the ISP side is far enough away
>> that it isn't affected? For a few years, I did this with a 12V inverter
>> connected to an EV (an electric car). It turns out the 12V system in many
>> EVs will provide 12V power through a DC step-down from the main traction
>> battery. I really only need like 15A and previous testing made me confident
>> I could safely do this as long as the main battery had capacity left. So, I
>> did that for a while, but earlier this year we sold the EV and became a
>> one-car household. So...what do I do? I had an inverter, if I could get
>> batteries and a way to charge them, I should be most of my way toward a DIY
>> UPS, right?
>>
>> Specs/Requirements
>> * AC power needed is typically about 150W, I typically use 300W as a
>> value for max surge. If I turn off my NAS, the load is only about 50-55W
>> AC. I was aiming for 2-3 days of power for this load, and can live without
>> the NAS during an outage, so I need 2.8-4.3kWh of capacity with the NAS off.
>>
>> * While I do want this to work, this is a fun personal project. Mucking
>> with it is part of the goal. I had some hobby money to spend, but not
>> infinite. I wanted to reuse things I had on hand or could get easily for
>> v1. I also get to decide how reliable it needs to be.
>>
>> The system is:
>> * AIMS Pure Sine 12V 600W Inverter. I had it already. Having this
>> inverter on hand drove the decision for 12V vs 24/48V. Also, power needs
>> are relatively low so 12V doesn't lead to more than 55A of current, and
>> that's only when charging from a deep discharge.
>>
>> * RV Converter/Charger: PowerMax PM4 55A 12V. This is a lead acid battery
>> charger that will also provide power after batteries are charged. Many
>> battery chargers are not designed to be run 24/7, this one is.
>>
>> * Two 12V 200Ah Renology AGM deep cycle batteries wired in parallel. Got
>> a deal on these. I decided I was ok with 75%-80% DoD even though these are
>> lead acid. This gives me about 3.5kWh of usable AC capacity.
>>
>> * Batteries and charger are wired up with 4AWG, the inverter is something
>> smaller, I think 6AWG?
>>
>>
>> What I have built is a double conversion online system. The inverter is
>> powering the AC load all the time. There's no transfer switch. There's
>> lower efficiency when power is on because the normal power path is always
>> AC->DC->AC. I did this because I wasn't confident in my ability to find a
>> transfer switch that would transfer fast enough and it was one more thing
>> to figure out and buy. In my head, this online architecture is simpler, but
>> I may change it in the next version. I worry a bit about the inverter being
>> ok running full time, but since it is rated for 600W and I use only 150W
>> all the time, I decided it's ok. When it fails, I'll figure out something
>> else.
>>
>> I chose lead acid deep-cycle batteries because if you're willing to
>> discharge them to 70-80% they're very cost effective vs LiFePO4 or other
>> lithium types. I know this will shorten the number of cycles I get from
>> them. I'm ok with that. In this application, they sit at 100% for all but
>> maybe a few hours to a few days a year. They may see one or two deep
>> discharges a year. If I get five years out of them, that's great!
>>
>> I calculated roughly 3.5kWh of usable capacity for these two wired in
>> parallel. Running with the NAS off is maybe 5A from the DC side of things,
>> which is a really low load for a 400Ah battery bank. They are very heavy,
>> but I already had a heavy duty storage rack next to the load, so that's not
>> a problem in this case. Also, the voltage range for 12V lead acid batteries
>> is still better supported than LiFePO4. Right now, there are still more
>> (and lower cost) chargers and inverters that assume a lead acid voltage
>> range. As an example, my inverter will shut down if it sees over about
>> 14.6V.
>>
>> So, how does this fit into NUT? One key aspect of my capacity planning
>> was: "normal load is ~150W, but if the NAS turns off, I can make that
>> 50-60W.". My NAS is a QNAP, it has NUT installed. Before this DIY UPS, I
>> was using an APC consumer UPS connected to the NAS via USB so it would turn
>> off 5 min after mains power went off. That's the behavior I wanted for my
>> DIY UPS.
>>
>> So how did I do this?
>>
>> Gear:
>> * Arduino Pro Micro clone. It has a micro USB port built in and is
>> commonly used for "make an Arduino appear to be some USB device" projects.
>> It can be powered over USB, or by 5VDC directly to pins.
>>
>> * AC detection module: https://www.amazon.com/gp/product/B082PWV586.
>> Gives me an opto-isolated "is the mains AC present" signal the Arduino can
>> read.
>>
>> * Raspberry Pi running NUT. I wish I didn't need this, but I do for now.
>> While building and debugging the Arduino code, I needed to modify the NUT
>> code. Those patches made it in v2.8.1 and v2.8.2 NUT releases, but I still
>> don't think my QNAP NAS has v2.8.2 available. I eventually plan to remove
>> this.
>>
>> I put the AC detection module and the Arduino inside the PowerMax
>> converter/charger enclosure, on a little 3D printed mount. The AC module
>> connect to the AC input terminals inside the PowerMax and then the signal
>> side connects to a pin on the Arduino and pulls it high (or low, I forget)
>> when the AC is gone. I run a USB cable out of the PowerMax case which
>> connects to the RPi running NUT. The RPi is powered by the inverter, and it
>> powers the Arduino over USB. The RPi stays on during a power outage.
>>
>> So now I can write some Arduino code that loops and checks the status of
>> a digital pin. How do I pretend to be a UPS in a way NUT will recognize?
>>
>> Some googling led me to the HIDPowerDevice project.
>> https://github.com/abratchik/HIDPowerDevice. That is a library for
>> Arduino MCUs that does all the protocol for getting an Arduino device to be
>> recognized as a HID compliant UPS device over USB. You use it by
>> periodically calling a `sendReport` function with various flags set. Ex:
>> PowerDevice.sendReport(HID_PD_REMAININGCAPACITY, &iRemaining,
>> sizeof(iRemaining));
>> PowerDevice.sendReport(HID_PD_PRESENTSTATUS, &iPresentStatus,
>> sizeof(iPresentStatus));
>>
>> `iPresentStatus` is a bit field with a ton of info in it, like:
>> PRESENTSTATUS_ACPRESENT, PRESENTSTATUS_DISCHARGING,
>> PRESENTSTATUS_CHARGING, etc. See the project for full details.
>>
>> So, now my Arduino code loop does this:
>> Check status of AC on/off pin.
>> Set/clear PRESENTSTATUS_ACPRESENT and set
>> PRESENTSTATUS_CHARGING/PRESENTSTATUS_DISCHARGING accordingly.
>> Call `sendReport` from the HIDPowerDevice library.
>> Sleep a second, loop.
>>
>> In reality, my loop does a little bit more than this. It loops every
>> second, but only sends a report if some status changed but waits no more
>> than every 5 seconds between reports in any case. NUT (and Windows, and
>> MacOS) seem to expect this.
>>
>> So, assuming I can get NUT to recognize the Arduino Micro as a UPS, this
>> should work. I had two problems getting NUT to recognize the Arduino:
>> 1) Will NUT recognize the default Arduino vendor and product id
>> (vid:pid)? The answer is YES! There is an Arduino subdriver for usbhid in
>> NUT. It looks like the HIDPowerDevice project author added this originally
>> a few years ago! See drivers/arduino-hid.c for the list of supported IDs.
>> If you end up with an Arduino device that has another vid/pid combo, it
>> would need to be added there.
>>
>> 2) When using the HIDPowerDevice library, the Arduino Micro presents as a
>> composite HID device, so it is more than one HID type at once. AFAICT, real
>> world examples of composite devices are rare, but it is in the HID spec. In
>> this exact case the Arduino presents as both serial/comm interface
>> (typically used for debug output when running code from the Arduino IDE)
>> and as a HID Power Device (the HID term for UPS status over USB). This all
>> works now as of NUT 2.8.2.
>>
>> Note that the Arduino subdriver is not as full featured as something like
>> the APC subdriver. I don't think it allows for NUT to set values on the
>> Arduino HID device. I don't know if the Arduino HIDPowerDevice library
>> supports this either. I have only tested the send-a-report-periodically
>> code path.
>>
>> NUT config
>> What I really wanted was for my NAS to shut down when mains power goes
>> away. My QNAP NAS runs NUT, but I needed 2.8.2 and getting a new version on
>> there was more than I wanted to tackle, especially since my PRs weren't in
>> a release version of NUT at that time. So I run a NUT server on a Raspberry
>> PI which is connected via USB to my DIY-NAS Arduino. The RPi does not react
>> to changes in the UPS at all. It makes them available over the network to
>> the NUT instance running on the QNAP NAS. The QNAP NAS is then configured
>> to poll the RPi NUT instance for UPS status and set to shut down if AC
>> power is out for 5 min. I would rather not deal with this extra RPi in the
>> setup, but it was the easiest way forward for me. Once NUT 2.8.2 is
>> available for my QNAP NAS. I'll get rid of it.
>>
>>
>> Optional Upgrade
>> DC voltage sensing to give an idea of remaining runtime or remaining
>> capacity. Since this is too long already, I'll try to be brief. One thing I
>> did a month or so after the initial install was add DC voltage detection to
>> the Arduino side of things:
>>
>> Gear:
>> * 0-25VDC voltage sensor (https://www.amazon.com/gp/product/B01HTC4XKY).
>> It's a voltage divider, let's my code sense the DC voltage.
>>
>> * External ADC: ADS1115 board. I wanted higher resolution DC voltage
>> detection.
>>
>> My code then changed to take readings from the ADS1115 and convert that
>> into a rough "50-100% capacity remaining" that I can report to NUT. It took
>> a while to get right and it's only "accurate enough", not "trust this to a
>> millivolt level of accuracy". For now it's just nice to have and I enjoyed
>> having to learn about ADC measuring on Arduino enough to get this accurate
>> enough to report with 1% differences in capacity.
>>
>> Future
>> I've been researching designing a PCB and doing an "all-in-one" UPS. I'll
>> talk more about that on the wiki page as well.
>>
>> I guess I should share my Arduino code on GitHub too.
>>
>> On Thu, May 16, 2024 at 10:59 AM gene heskett via Nut-upsuser <
>> nut-upsuser at alioth-lists.debian.net> wrote:
>>
>>> On 5/16/24 08:59, Jim Klimov via Nut-upsuser wrote:
>>> > I agree with earlier posters, such documentation can help future
>>> > tinkerers. There is probably more than just one to hold the hand and
>>> > walk through the ordeals :)
>>> >
>>> > Perhaps a new page at https://github.com/networkupstools/nut/wiki
>>> > <https://github.com/networkupstools/nut/wiki> can be a good
>>> location...
>>> >
>>> > Jim
>>> >
>>> Great Idea Jim.
>>> >
>>> > On Thu, May 16, 2024 at 1:29 PM Bill Gee <bgee at campercaver.net
>>> > <mailto:bgee at campercaver.net>> wrote:
>>> >
>>> > Hi Kelly -
>>> >
>>> > As an Arduino nerd, I am interested in this! I am sure others on
>>> the
>>> > list would be interested. If nothing else, it would be nice to
>>> have
>>> > some documentation in the archives.
>>> >
>>> > I assume you set it up as an online system rather than a standby
>>> > system.
>>> > Right? If true, then the choice of inverter is fairly
>>> critical. It
>>> > has to be bomb-proof reliable.
>>> >
>>> > What did you choose for battery voltage? What is the power
>>> capacity of
>>> > the inverter?
>>> >
>>> > Which Arduino did you use? All of my Arduino projects use the Pro
>>> > Mini,
>>> > though it would be quite easy to get some other model for this.
>>> >
>>> > Thanks -
>>> > ===============
>>> > Bill Gee
>>> >
>>> > On 5/15/24 20:11, Kelly Byrd wrote:
>>> > > I put together my own DIY UPS, it's a RV charger/converter, an
>>> > > inverter, and some batteries. I use an Arduino and the
>>> > HIDPowerDevice
>>> > > library (https://github.com/abratchik/HIDPowerDevice
>>> > <https://github.com/abratchik/HIDPowerDevice>
>>> > > <https://github.com/abratchik/HIDPowerDevice
>>> > <https://github.com/abratchik/HIDPowerDevice>>) to get it to talk
>>> to
>>> > NUT.
>>> > > Been working great for months!
>>> > >
>>> > > The Arduino is connected to two modules:
>>> > > * AC detection circuit to measure mains power on/off
>>> > > * Voltage divider and an external ADC to get a reasonably good
>>> DC
>>> > > voltage level for the battery which I turn into the a charge
>>> > percentage.
>>> > >
>>> > > This uses the USBHID driver in NUT and "just works" as long as
>>> > you're
>>> > > using NUT 2.8.2 or later. I used the example code in the
>>> > HIDPowerDevice
>>> > > library as a starting point for running on my Arduino.
>>> > >
>>> > > I can share more specifics about the Arduino side of things off
>>> > list if
>>> > > you want, the NUT side of things is pretty boring and normal.
>>> > >
>>> > > On Wed, May 15, 2024 at 3:27 PM Kiril Zyapkov via Nut-upsuser
>>> > > <nut-upsuser at alioth-lists.debian.net
>>> > <mailto:nut-upsuser at alioth-lists.debian.net>
>>> > > <mailto:nut-upsuser at alioth-lists.debian.net
>>> > <mailto:nut-upsuser at alioth-lists.debian.net>>> wrote:
>>> > >
>>> > > Hello,
>>> > >
>>> > > I found out about NUT just days ago while searching for a
>>> > solution
>>> > > for my home setup. After some digging through the interwebs,
>>> > I come
>>> > > to you with questions.
>>> > >
>>> > > I'm putting together a DIY 12V UPS, very similar to what
>>> this
>>> > guy did:
>>> > >
>>> > > [1]
>>> > >
>>> >
>>> https://baldpenguin.blogspot.com/2015/10/diy-12v-ups-for-home-network-equipment.html
>>> <
>>> https://baldpenguin.blogspot.com/2015/10/diy-12v-ups-for-home-network-equipment.html>
>>> <
>>> https://baldpenguin.blogspot.com/2015/10/diy-12v-ups-for-home-network-equipment.html
>>> <
>>> https://baldpenguin.blogspot.com/2015/10/diy-12v-ups-for-home-network-equipment.html
>>> >>
>>> > >
>>> > > The objective is to keep a bunch of mini PCs and network
>>> gear
>>> > online
>>> > > for as long as the battery lasts and then provide a
>>> mechanism
>>> > for a
>>> > > graceful shutdown of my NAS and other appliances for which
>>> > cutting
>>> > > power would not be healthy. The project above is missing the
>>> > > "connected" part. I want to get mine to play with NUT
>>> nicely.
>>> > Other
>>> > > prior art is this project:
>>> > >
>>> > > [2] https://github.com/xm381/Raspberry-Pi-UPS
>>> > <https://github.com/xm381/Raspberry-Pi-UPS>
>>> > > <https://github.com/xm381/Raspberry-Pi-UPS
>>> > <https://github.com/xm381/Raspberry-Pi-UPS>>
>>> > >
>>> > > Mentioned in a previous thread here:
>>> > >
>>> > > [3]
>>> > >
>>> >
>>> https://alioth-lists.debian.net/pipermail/nut-upsuser/2018-August/011198.html
>>> <
>>> https://alioth-lists.debian.net/pipermail/nut-upsuser/2018-August/011198.html>
>>> <
>>> https://alioth-lists.debian.net/pipermail/nut-upsuser/2018-August/011198.html
>>> <
>>> https://alioth-lists.debian.net/pipermail/nut-upsuser/2018-August/011198.html
>>> >>
>>> > >
>>> > > A valid approach -- emulates an existing protocol on an
>>> arduino.
>>> > >
>>> > > Are there other similar projects that you know of? I found
>>> > plenty of
>>> > > "DIY UPS" projects, but none were "smart".
>>> > >
>>> > > I am able to put together firmware for some micro which
>>> will take
>>> > > care of measuring voltages, currents, possibly also turn
>>> on/off
>>> > > loads, serial or USB or IP are options. Not sure yet what
>>> > hardware
>>> > > features I'll put together, but this depends somewhat on the
>>> > > approach for getting this thing integrated with NUT. PSUs
>>> and
>>> > > batteries are already on the way, and my junk drawers have
>>> most
>>> > > other parts I may need.
>>> > >
>>> > > So, options found so far:
>>> > >
>>> > > * Use genericups. Least favorite option, very limited
>>> features
>>> > >
>>> > > * Use the same approach as [2]. If I were to go that route
>>> --
>>> > which
>>> > > is the best protocol to pick for emulation? I'm looking for
>>> > > something simple, extensible/flexible and well-documented.
>>> > >
>>> > > But what I really wish was possible was the ability to
>>> > describe my
>>> > > device in some format, feed it to a generic driver in NUT
>>> and
>>> > > profit. I see some efforts have been made in this
>>> direction, most
>>> > > notably:
>>> > >
>>> > > [4]
>>> > >
>>> >
>>> https://github.com/networkupstools/nut/wiki/Data-Mapping-File-(DMF)
>>> > <
>>> https://github.com/networkupstools/nut/wiki/Data-Mapping-File-(DMF)>
>>> > >
>>> > <
>>> https://github.com/networkupstools/nut/wiki/Data-Mapping-File-(DMF) <
>>> https://github.com/networkupstools/nut/wiki/Data-Mapping-File-(DMF)>>
>>> > >
>>> > > What is the state there? Is it usable for USB HID? Or, how
>>> hard
>>> > > would it be to make it usable? Even a modbus description
>>> will
>>> > do --
>>> > > implementing the modbus server (yes, server, I'm being
>>> > > politically-correct) over serial or even TCP is easy, if
>>> only
>>> > there
>>> > > was a way to dump a CSV with register descriptions in some
>>> > magical
>>> > > driver...
>>> > >
>>> > > And yet another approach which comes to mind is to
>>> implement my
>>> > > driver as an external executable. This may be completely
>>> > unfeasible
>>> > > and stupid, and please let me know if it is. But, from what
>>> I
>>> > > gather, drivers run in their own process and talk to the
>>> > daemon via
>>> > > a UNIX socket. Why not make it possible for the driver to
>>> be just
>>> > > any executable, built/deployed outside of the NUT codebase?
>>> The
>>> > > socket protocol seems simple enough, and this will allow
>>> for ...
>>> > > creativity. It could be implemented in any language
>>> (including
>>> > > scripting languages) and need not depend on anything
>>> > NUT-specific,
>>> > > other than maybe some common CLI interface and/or
>>> configuration.
>>> > >
>>> > > I'm hoping the NUT masters will have some insight. Thanks
>>> for
>>> > > working on this!
>>> > >
>>> > > Cheers,
>>> > > Kiril
>>> > > _______________________________________________
>>> > > Nut-upsuser mailing list
>>> > > Nut-upsuser at alioth-lists.debian.net
>>> > <mailto:Nut-upsuser at alioth-lists.debian.net>
>>> > > <mailto:Nut-upsuser at alioth-lists.debian.net
>>> > <mailto:Nut-upsuser at alioth-lists.debian.net>>
>>> > >
>>> >
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>>> > <
>>> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser>
>>> > >
>>> > <
>>> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser <
>>> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser>>
>>> > >
>>> > >
>>> > > _______________________________________________
>>> > > Nut-upsuser mailing list
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>>> > >
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>>> Cheers, Gene Heskett, CET.
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