OpenWRT One: USB disconnects

Installing and Using OpenWrt
1

Using the One with 24.10.5 image.

I run apcupsd to monitor my BackUPS 550. This morning I noticed something in the logs (filtered down):

2026-01-09T01:10:10-08:00 OpenWrt kernel: [1093467.348077] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T01:10:16-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T01:17:56-08:00 OpenWrt kernel: [1093933.664669] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T01:18:03-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T01:40:01-08:00 OpenWrt kernel: [1095258.237603] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T01:40:07-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T02:08:52-08:00 OpenWrt kernel: [1096988.715695] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T02:08:58-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T02:37:46-08:00 OpenWrt kernel: [1098722.492039] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T02:37:53-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T02:51:49-08:00 OpenWrt kernel: [1099564.639229] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T02:51:55-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T03:12:26-08:00 OpenWrt kernel: [1100801.516434] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T03:12:32-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T03:46:47-08:00 OpenWrt kernel: [1102862.175283] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T03:46:53-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T03:59:46-08:00 OpenWrt kernel: [1103641.273801] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T03:59:52-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T04:16:01-08:00 OpenWrt kernel: [1104615.267931] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T04:16:07-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T04:51:16-08:00 OpenWrt kernel: [1106730.577491] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T04:51:23-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T05:26:43-08:00 OpenWrt kernel: [1108856.332511] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T05:26:49-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T05:43:15-08:00 OpenWrt kernel: [1109847.963352] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T05:43:21-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T06:15:43-08:00 OpenWrt kernel: [1111795.750650] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T06:15:49-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T06:34:55-08:00 OpenWrt kernel: [1112947.783478] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T06:35:01-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.
2026-01-09T06:44:17-08:00 OpenWrt kernel: [1113509.575861] usb usb1-port1: disabled by hub (EMI?), re-enabling...
2026-01-09T06:44:23-08:00 OpenWrt apcupsd[2194]: Communications with UPS restored.

AFAIK this has never happened before, either on the One or on the Raspberry Pi where I had apcupsd running in the past. I assume EMI means "electromagnetic interference"? What could be the source? Nothing in the room changed, to my knowledge. Except ... it was the coldest night this season, so far --- it dropped to 6 deg C if I should believe the sensor on my Pi. And those are the only times it happened, so it overlaps exactly with the coldest stretch ...

2

So temp dropped inder 0C?

3

Time for a battery refresh on your UPS maybe?

4

@brada4 : No, 6 C as I wrote. For me, that's plenty cold :coat:

@RuralRoots : The UPS itself thinks it's fine (when it's online):

APC      : 001,035,0882
DATE     : 2026-01-09 14:55:18 -0800
HOSTNAME : OpenWrt
VERSION  : 3.14.14 (31 May 2016) unknown
UPSNAME  : ups1
CABLE    : USB Cable
DRIVER   : USB UPS Driver
UPSMODE  : Stand Alone
STARTTIME: 2025-12-27 09:21:42 -0800
MODEL    : Back-UPS ES 550G
STATUS   : ONLINE
LINEV    : 123.0 Volts
LOADPCT  : 0.0 Percent
BCHARGE  : 100.0 Percent
TIMELEFT : 450.0 Minutes
MBATTCHG : 5 Percent
MINTIMEL : 3 Minutes
MAXTIME  : 0 Seconds
SENSE    : Medium
LOTRANS  : 92.0 Volts
HITRANS  : 139.0 Volts
ALARMDEL : 30 Seconds
BATTV    : 13.7 Volts
LASTXFER : Low line voltage
NUMXFERS : 1
XONBATT  : 2026-01-03 10:44:43 -0800
TONBATT  : 0 Seconds
CUMONBATT: 9 Seconds
XOFFBATT : 2026-01-03 10:44:52 -0800
STATFLAG : 0x05000008
SERIALNO : 0B2321N01624
BATTDATE : 2023-05-24
NOMINV   : 120 Volts
NOMBATTV : 12.0 Volts
FIRMWARE : 904.W1 .D USB FW:W1
END APC  : 2026-01-09 21:45:16 -0800
5

Looks like I was right to suspect the weather --- kind of. It was mostly my electrical blanket :tongue: It's still freezing here but I used lower tech warming means last night, and it didn't happen even once.

Then today it happened once at 2 PM. I don't know what to blame that on, some people on stack overflow write that passing motorbikes (!) can be source of EMI. Anyway, I find a frequency of once per day acceptable.