Short answer: in an outage, the iPhones keep running on battery but drop off the Mac as soon as the hubs lose power, and the Mac stops unless it's a laptop or on a UPS. Put the Mac, the hubs and the router on a UPS sized from their rated wattage, turn on "Start up automatically after a power failure" on the Mac, and make sure your automation resumes on its own.
What happens when the power goes
| Device | Without a UPS | With a UPS |
|---|---|---|
| Mac mini / desktop | Switches off; any run ends | Keeps running for the UPS runtime |
| MacBook | Runs on battery | Same |
| Powered hubs | Switch off; every phone disconnects | Keep phones connected |
| iPhones | Stay on battery, but lose the Mac | Stay connected and charging |
| Router / modem | Off; phones lose internet | Online if on the UPS |
A post that was mid-upload when the internet dropped may or may not have gone out. That uncertainty matters more than the lost minutes.
Sizing a UPS
We won't give a number for your rack; it depends on your hardware. The method:
| Step | How |
|---|---|
| 1. List the loads | Mac, each hub's power adapter, router, modem |
| 2. Add up watts | Use the rated wattage on each adapter as the worst case |
| 3. Add headroom | Assume 25% on top so the UPS isn't running at its limit |
| 4. Pick runtime | Assume 10–15 minutes: enough to ride out blips or shut down cleanly |
| 5. Check the maker's runtime chart | Match your wattage to the runtime the UPS maker lists |
A worked example with assumed figures: a Mac rated 150 W, two hubs with 120 W adapters, and a router at 30 W is 420 W worst case; with 25% headroom, look for a UPS rated well above 525 W and read its runtime chart at that load. Real draw is usually lower than the rated maximum, so this errs on the safe side.
Other things to check:
- Hub adapters count. Every powered hub has its own adapter, and all of them belong on the UPS — see USB hubs.
- Output type. Some power supplies are sensitive to the stepped output of cheaper units; a pure sine wave UPS avoids the question.
- Enough outlets on battery, not just surge-only outlets.
- USB or network monitoring so the Mac knows it's on battery.
Set the Mac up to recover
Apple lists these under System Settings → Energy on Mac desktops (Apple Support, checked 17 September 2026):
- Start up automatically after a power failure — on.
- Prevent automatic sleeping when the display is off — on.
On Mac mini (2024 and later) with macOS 26.5 or later, Apple also offers Start up when power is connected; set it to Always (Apple Support).
Then make sure the farm comes back without you:
- Automatic login for the farm user, weighed against physical security.
- The automation app in Login Items.
- Router and modem on the UPS or set to power back on.
- Hubs that restore power to their ports when power returns — test it once.
If the UPS connects to the Mac over USB, look in Energy settings for its options once it's plugged in, then test a real outage once on purpose, on a quiet evening.
After the power comes back
- Check every phone is back on the Mac.
- Check posts that were in flight. Look at the account's profile before re-posting anything.
- Check phones didn't fall into Low Power Mode if their batteries ran low; it shortens Auto-Lock. See iPhone keeps disconnecting.
With Farmero
Farmero resumes after crashes and disconnects. A post it can't confirm is marked "uncertain" and is never retried automatically, so an outage mid-upload doesn't turn into a double post; you check that account and decide. Farmero reports what posted and what didn't on the Mac, and optionally to Telegram or ntfy — see remote monitoring. Host settings are in Mac mini as a host.
FAQ
Do I need a UPS for a phone farm?
Not to start. Once you rely on overnight runs, a UPS for the Mac, hubs and router stops short blips from ending every run.
What size UPS does a phone farm need?
Add up the rated watts of the Mac, hub adapters and router, add headroom, and pick a unit whose runtime chart covers that load for 10–15 minutes.
Will my Mac turn back on after an outage?
It will if "Start up automatically after a power failure" is on in System Settings → Energy.
Do the iPhones need a UPS?
They have their own batteries. The hubs they connect through need power, or the phones disconnect from the Mac.