Hacker News Reader

Comment by r00fus | Hacker News Reader

What's the goal of having a MacMini running off an external battery? I mean, it seems less cost effective than just getting a MB Air and not using the screen...

View on HN

The goal of most of these projects are usually to demonstrate that they're possible. Actual use cases are left as an exercise for the reader.

Headless servers where you want a modular or easily removable battery backup.

I really wish desktop PC power supplies would support such a thing. It seems stupid that we need to use a UPS with an inverter when the power supply should be rigged to accept DC input straight from a battery.

Exactly, the PC PSU coverts AC to 12v for the PC anyway, so 12v batteries should slot into that scheme, without a separate PSU and inverter.

You would still need a DC to DC converter as lead acids deliver anywhere from 12.8 to about 10v depending on SoC and load.

Remember that DC to DC power supplies are much smaller because existing AC PSU has to deal with the transformer aspect.

I worked for an ISP that was also a CLEC back in late 90s / early 2000s. All of the telco side was DC (massive 48v battery banks) - so when we were doing server implementation it made sense to get all DC PSU on the servers. Not sure why DC PSU aren't a more universal option as you'd think UPS providers could easily offer DC output models.

There are options out there, I ran across this [0] looking for typical ATX DC to DC PSU.

[0] https://lazer3d.com/dc-dc-power-supply-guide/

For anything larger than about 500W that'd become untenable because at 12V as you'd need cables that can carry in excess of 50A.

UPS systems start connecting the batteries in series to provide higher voltages for this reason

Or multiple cables, just as PC power supplies of 500w+ have, and in fact some of their power is delivered at 5v.

Even more annoying is why aren't decent USB-only ups systems?

just ditch the 110 outlets for usb-a or usb-c ports and skip the inverter.

I'd love to power a pi or 3 from ups-based usb ports.

Where I live, this is actually extremely common now - typically referred to as a "Mini DC UPS" [1].

These cheaper ones just provide 9V and 12V output to power a fibre and/or WiFi router, as well as 5V USB-A, and start at around 30Wh capacity - some for less than USD 20. If you pay a little more, you can get 24/48V PoE included as well.

Unfortunately, ones providing USB-PD are quite rare. You do get "power stations" [2] with USB-PD (in addition to an AC inverter). These are typically USD 100 - USD 1000, and have much larger capacity.

Examples (I haven't tested these and do not specifically recommend them):

[1]: https://www.amazon.com/Lithium-Battery-Appliance-Monitor-uni...

[2]: https://www.amazon.com/Portable-Solar-Panel-Power-Station-Ge...

Yeah that would be great. Pimoroni makes a version of the Pi Pico that takes a LiPo battery and automatically switches to battery power when the USB power goes away, but I don't know of any full computers that support that. I think adafruit makes a LiPo addon for picos. I wonder if it could be modded to work on a zero or something?

That's where USB-C PD is nice. It's all DC at several different voltages the recipient can request. The only downside is it's not quite powerful enough for many desktop PCs, but it's getting better.

Pretty much expect the Mini to end up this way within a few generations. Somebody in the Mac team really hates wall warts, but given all their other hardware is going USB-C one would think they’d want to standardize & eliminate the space/heat of the internal power supply.

Avoiding the inevitable spicy pillow seems like a good reason

An external/easily replaceable battery would be excellent come time to deal with cell age

Does this read like an attack against Apple laptops specifically, or something? Already -2 five minutes after posting it.

Leaving as-is for feedback. I don't get the controversy. I could've been a jerk and said just buy a UPS - this is an established concept.

Edit: thank you kind souls for restoring the imbalance - carry on :D

Not really. However, as a long-time Mac and Apple fan, I can say the community has a lot of overly aggressive people who can't stand any criticism (valid or not) of Apple and will do various things in retaliation.

No it just reads as kinda paranoid because li-ion cells typically become spicy pillows long after the device becomes obsolete. It's also trivial to avoid by limiting cell voltage. Many devices, most notably iPhones, automatically go into kiosk mode after charging for a few days for exactly this reason: https://support.apple.com/en-gu/HT208710

Definitely disagree. My own anecdotal evidence is that many many laptops left plugged in 24/7 will develop a spicy pillow after a year or two. That includes a set of Apple laptops and hundreds of Dell laptops.

Anecdotally: this has never happened to me despite owning a whole bunch of laptops over the past 25 years or so.

Thank you for taking the time to follow up!

Definitely a bit paranoid - even if I'd prefer to call it robust :)

I've had very bad luck in this regard... but haven't honestly used a laptop in probably a decade. I was pleasantly surprised to see my latest (dust-collecting) Lenovo will stop somewhere around 80%!

Point being, sure - there are safety things... but batteries are consumables. I like these things to be easy-to-replace!

I find these being difficult to replace accelerates this pattern of obsoleting. CPUs and (especially disks) tend to pack plenty of punch/life, these days - well beyond the mechanical/chemical things they depend on.

Something to ponder - these chips may see particularly long use, being so power efficient. The utility bill won't be such a driver, sipping power and parallelizing decently.

> ... but batteries are consumables. I like these things to be easy-to-replace!

Replaceable, consumable batteries often get thrown out in the trash. ... and can set garbage trucks and recycling centers on fire.

https://www.waste360.com/safety/lithium-ion-batteries-are-ca...

https://www.dispatch.com/story/news/local/2023/02/09/garbage...

https://arstechnica.com/gadgets/2022/12/recycling-firm-fined...

https://gothamist.com/news/lithium-ion-batteries-a-growing-f...

https://www.abc.net.au/news/2023-05-29/garbage-truck-fires-c...

(and many more)

How does one make sure that removable, consumable, high capacity batteries are not discarded as trash but instead taken to the proper facilities to handle them?

Respectfully, today people just chuck the entire phone/laptop in the bin. I don’t think making the battery module removable changes the outcome one bit, except that it would allow a tremendous amount more life out of these devices, reducing all the other (non-battery) waste streams and reducing the environmentally costly manufacture of new devices…. which is the reason why the shareholders love the current strategy and why all electronic manufacturers are moving the same way. Why allow users to get 3 more years of life from their laptop when you could convince them it’s e-waste after 3 because of a $15 battery?

We can't. Instead we're making it worse by selling disposable vapes with rechargeable li-ion batteries [1].

[1] https://www.recyclingmagazin.de/2023/07/17/das-ungenutzte-po...

Is the dichotomy here really that we can either have modular batteries, or we can have more intact waste trucks and workers?

However, having just taken an entire stroller out of my shared duplex recycling bin, I know there will never be an ethical way to get 100% of people to care enough to dispose of waste properly.

I wish I knew a good answer - this is an excellent concern. I'm skeptical of recyclers/waste centers, but that's what I've got.

Having things that are have special handling for disposal not be as user serviceable is one solution... but that goes against the replaceable battery.

The AA lithium ion batteries getting tossed into the trash and setting garbage trucks on fire are problematic enough. The energy capacity of a cell phone is quite a bit more and correspondingly more spectacular in the combustion.

From iFixit:

https://www.ifixit.com/News/69041/how-batteries-can-catch-fi...

https://www.ifixit.com/News/34034/lithium-ion-batteries-are-...

> USA Today reports that 65 percent of fires at waste facilities in California were started by lithium-ion batteries. In a 2018 survey of 21 waste facilities across California, 86 percent reported a fire at their facility in the last two years, according to the California Products Stewardship Council (CPSC). Of those fires, 56 percent were attributed to batteries, with the remainder attributed to “traditional hazards of combustibles.” In other words, batteries are causing more fires than the oils, fuels, and other hazardous materials of waste management—combined.

> And that’s only the fires actually reported.

heh, I understood what you meant by "spicy pillow" from context but it's a new phrase for me, I like it

Can you explain

https://www.reddit.com/r/spicypillows/

The batteries puff up like an overstuffed pillow and if you let the spice out, you're going to have a bad time.

lipo batteries expand

The article is about a Mac Mini. Those machines are mains powered, not battery powered.

I was replying to a question on why one wouldn't "just get a MB Air/not use the screen"... not the article.

How is this relevant? I don't say this to be rude, but this internet phenomenon of relentless pedantry is annoying.

Things tend to make [some degree of] sense when your first reaction isn't to shoot from the hip.

Mains batteries exist - most people should save the effort, get a UPS. Hackers on the other hand... it's kind of silly to ask why. The answer is 'because'.

No idea, but if they got it running on USB PD, battery pack aside, it would make it a one cable connection to a monitor that has PD support. Multiple cords don’t actually bother me but it sounds kinda neat.

Anyhow I guess the goal is “because you can”

I could see it making sense in a 'van life' context to use a smaller local battery rather than plug everything in to your main leisure battery. Use the latter to charge Makita packs say and then run most other stuff off those (there's a decent amount of open 3D printable adapters for them, as well as third-party/AliExpress stuff).

Would make way way more sense to have a macbook that you can then charge direct from a DC battery over USB-C. With the mac mini you still have to work out how to power an external screen as well.

There's a lot of low power HD screens out there. It's not super difficult. Not the ideal case for sure but low power is all about tradeoffs.

Battery aside, POE also allows you to put it anywhere you have ethernet cable with sufficient power delivery. In this case you could have a workstation powered entirely off ethernet delivered to the location (some monitors will also work with a POE splitter as well).

That it happens to be 12 volts DC has some value versus whatever power loss an inverter has for use in a vehicle. Though I'm with you on the relative ease of starting with a laptop instead.

> it seems less cost effective than just getting a MB Air and not using the screen...

how ? why would paying for a screen and not use it be cheaper ?

Economy of scale, mostly.

E.g. to run home automation in case of a power outage. I have an Intel NUC with a li-ion DC UPS exactly for this reason.

In the event of that solar flare that wipes out the grid.

In that event, personal computing will be the least of our worries

Two large monitors or projectors with Mac mini.

cheaper and bigger batteries? always replaceable in the future? And tbh laptop batteries are not meant to be used 24/7, personally would avoid it.

This would be fun for when LEOs come in to take your computer, they can easily keep it powered so all of the decrypted keys stay in memory. Killing power means going back to an encrypted state. In high profile cases for desktops, there's techniques for splicing the power cable to switch to a battery pack. This would make it much easier for the unskilled LEO to take your shit. Cause we all know you're the one they're after. Sleep tight! ;-)

That's why pretty much all desktop and server mobos have a "chassis intrusion" header that you can connect to a sensor/switch. Your machine should wipe keys or reboot if it's opened or moved.

how does that work if the case is never opened?

You can connect multiple switches in series. Eg one could be a reed switch that detects whether the PC is within 1mm of a tiny magnet in the floor.

This is a good idea! Kind of makes me wish I was a drug kingpin with a PC full of secrets so that I could justify trying that. Sadly I would just end up with a kid rebooting the PC by bumping into it :D

Reply on news.ycombinator.com