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Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

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Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#71

Post by Gigachad »

OJFord wrote: post #37
r00fus wrote: post #19

Earlier quoted context omitted.

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...

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#72

Post by numpad0 »

jcrawfordor wrote: post #24
evadne wrote: post #21

Earlier quoted context omitted.

Passive PoE is always on Active PoE is negotiated with handshake

Yes, but passive PoE is almost universally at 24v, and per the Ethernet spec (as quoted above) an Ethernet PHY should tolerate 24v fine. This is important as transients from nearby lightning or occasionally even coupling to power cables can produce this kind of voltage. Ethernet connectors are magnetically coupled for protection from these transients. The problem with PPoE in these cases is, I think, not the voltage…

Looks like PoE uses pin 4 and 5 for +48V, and 7 and 8 for GND, which respectively are pair C and D of GbE. On ISDN, pinout could vary but one I could find said 1-2, 4-5 for V+ and 3-6, 7-8 for V-. In either cases, both sides of isolation magnetics are connected to pins of same potential and current is only proportionate to voltage imbalance within each pair which should be minuscule.

I wonder if the problem is that 1:1 signal transformers for decoupling are being replaced with simple DC blocking circuit. That can be most simply done with a spare 0.1uF and an R10k per pin, which by the way generate load of from V/R=I 48V/10kohm = 5mA and 48V * 5mA = 230mW > 1/6W. That could cause resistor to burn off if phone-sized components would be used. Or if the cap might only be rated for 10V, it could burn open. I have nothing to support these hypothesis though. I could be entirely off.

Also I suspect the "passive PoE" mentioned above could be cheap injectors with very rounded corners and always active 48V. Those are widespread for surveillance cameras and other neckbeardy applications.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#73

Post by cyberax »

r00fus wrote: post #19
ravetcofx wrote: post #6

" the M1 Mac mini was the perfect hardware to test out PoE, as on idle, the device only consumes 6W. When some load is applied to the internals, that power draw can go up to 40W. After some thorough research, we found out that the maximum throughput of Power over Ethernet was 15.4W " They'll have to bump it up to 802.3bt (Poe ++) which can support 60W. Cool Project though, I've been wanting to mod my Mac Mini m1 to r…

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...

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#74

Post by kposehn »

ravetcofx wrote: post #6

" the M1 Mac mini was the perfect hardware to test out PoE, as on idle, the device only consumes 6W. When some load is applied to the internals, that power draw can go up to 40W. After some thorough research, we found out that the maximum throughput of Power over Ethernet was 15.4W " They'll have to bump it up to 802.3bt (Poe ++) which can support 60W. Cool Project though, I've been wanting to mod my Mac Mini m1 to r…

I'm going to try this with my extra Mac mini and one of my switches that outputs POE++ at the full 60w. I should even be able to do this using a fairly bog-standard POE splitter from POE Texas that'll actually deliver a full 60W.

Edit: Here's the injector I'll probably use - https://shop.poetexas.com/collections/splitters/products/gbt...

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#75

Post by kposehn »

r00fus wrote: post #19
ravetcofx wrote: post #6

" the M1 Mac mini was the perfect hardware to test out PoE, as on idle, the device only consumes 6W. When some load is applied to the internals, that power draw can go up to 40W. After some thorough research, we found out that the maximum throughput of Power over Ethernet was 15.4W " They'll have to bump it up to 802.3bt (Poe ++) which can support 60W. Cool Project though, I've been wanting to mod my Mac Mini m1 to r…

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...

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).

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#76

Post by WWLink »

r00fus wrote: post #19
ravetcofx wrote: post #6

" the M1 Mac mini was the perfect hardware to test out PoE, as on idle, the device only consumes 6W. When some load is applied to the internals, that power draw can go up to 40W. After some thorough research, we found out that the maximum throughput of Power over Ethernet was 15.4W " They'll have to bump it up to 802.3bt (Poe ++) which can support 60W. Cool Project though, I've been wanting to mod my Mac Mini m1 to r…

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...

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#77

Post by WWLink »

NavinF wrote: post #57
bravetraveler wrote: post #31

Earlier quoted context omitted.

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

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#78

Post by WWLink »

bravetraveler wrote: post #31
bravetraveler wrote: post #27

Earlier quoted context omitted.

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#79

Post by bravetraveler »

NavinF wrote: post #57
bravetraveler wrote: post #31

Earlier quoted context omitted.

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

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

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.

Re: Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC

#80

Post by SV_BubbleTime »

CameronNemo wrote: post #41
dheera wrote: post #35

Earlier quoted context omitted.

I'm very skeptical of PoE now after 3 PoE adapters killed 3 Raspberry Pis I have. I wouldn't want to risk something more expensive to that shit. At this point I'd rather just have straight up 19V + and - cables bundled together with the Ethernet with some heatshrink around the whole thing to make it look like 1 cable.

You sure you want to blame poe as a whole instead of the RPI hat?

It’s definitely that.

PoE is fine and the issue surely lies on some $5 Chinese rasppi part with little buffering and protection circuitry.

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