Re: [Apcupsd-users] apcupsd not showing any UPS load

[Ted M. <te...@mi...>]

The older SMC model UPSes used the UPSLink protocol that was compatible 
with apcupsd

The newer SMC model UPSes use the Microlink protocol that is not.

I think a lot of people were hoping that with the reverse-engineering of 
the microlink protocol that someone would write support into either NUT 
or apcupsd.

The NUT project eventually copied the MODBUS driver out of apcupsd and 
use it with their project now.

The Smartcard slot in the SMT models allow you to install a web card 
with an ethernet port that does NOT require access to APC's website

The green ethernet ports on their newer UPSes require a yearly fee to be 
paid to their website to "monitor"


 From experience, I can tell you with purchasing for an enterprise today 
for the US market, these are the models of UPSes that I buy - all are 
compatible with apcupsd:

The first 2 are for workstations - we don't often get much call for 
these and I have pretty strict requirements on a user who wants a UPS - 
almost always, we will swap out their desktop with a laptop long before 
we give them a UPS.  Sometimes I will use these for remote switches in 
cabinets.   These work fine with apcupsd and a USB cable - they use the 
USB-UPSHID protocol:

APC UPS Battery Backup, 1050VA UPS with 6 Backup Battery Outlets, Type C 
USB Charging, BE1050G3 Back-UPS

APC BACK-UPS 850VA part # BE850G2

Tjese 3 are for larger server rooms, remote domain controllers and the like

APC 1500VA Smart UPS with SmartConnect, SMT1500C Sinewave UPS Battery 
Backup, AVR, 120V, Line Interactive Uninterruptible Power Supply


APC 2200VA Smart UPS with SmartConnect, SMT2200RM2UC Rack Mount UPS 
Battery Backup, Sinewave, AVR, 120V, Line Interactive Uninterruptible 
Power Supply


APC 1500VA Smart UPS with SmartConnect, SMT1500RM2UC Rack Mount UPS 
Battery Backup, Sinewave, AVR, 120V, Line Interactive Uninterruptible 
Power Supply

In the US new and modern commercial construction dictates 20A 120V.   I 
have experimented with 30A 125V circuits but ultimately I have found 
with modern server gear the power requirements are not high enough to 
justify the extra cost of specialty connectors and so on for 3000VA UPSes.

I use the 1500VA units in older buildings where the power is 
questionable - the outlet isn't on a dedicated circuit, or something 
like that.

It's imperative to properly size UPSes and NOT to oversize them!!!!   
You want the load no less than 20%.  Otherwise what happens is when the 
UPS self-tests, there's not enough load on the batteries to get proper 
calculation of battery discharge curve and over time the UPS will 
display inaccurate battery life.  If you don't get 20% load then use a 
smaller UPS

Ted

On 11/27/2025 9:45 AM, Jeffery Small wrote:
> Trev via Apcupsdusers<apc...@li...>  writes:
>
>> Jeffery Small wrote on 27/11/25 10:56 am:
>>> Xubuntu:    24.04.3
>>> apcupsd:    3.14.143.1build2  (standard Ubuntu package)
>>> UPS:	    New APC SMC1500C with USB connection
>>>
>>> I just built a new Linux workstation with a new APC UPS.  Everything is
>>> running fine except that the monitor is showing no load despite all of
>>> my equipment plugged into the UPS.  Here is a link to a screenshot:
>>>
>>> http://cjsa.com/misc/apcupsd_01.png
>>>
>>> Any reason that this is happening?  On my previous system with the same UPS
>>> which was more than five years old, all of this worked fine.  Could this
>>> be a configuration issue?
>> It is unclear to me whether you are using the same UPS. You say it's a
>> new APC UPS and later the same UPS. I'd hazard a  guess that it is a new
>> UPS and very probably has a different firmware. APC's USB firmware
>> versions have been notoriously buggy. Is there a firmware update for the
>> new UPS? If so, apply it and hope.
>> Alternatively:
>> 1) try the modbus protocol as someone has already helpfully suggested; or
>> 2) try a USB->RS232 converter if you have a serial port on your new
>> computer.
> It is a new UPS but when I said it was the same, I meant identical model:
> SMC1500C hooked up the same using USB.
>
> Thanks for the suggestions, both from you and other.  I'll report if I
> have success.  I'll see if there is new firmware and load it.  I have been
> loath to connect the UPS to the network because it looks like Schneider
> has go the route of Microsoft and others and wants to own and control your
> equipment.  I don't want them on my LAN. :-(
>
> Do people think that the self-test option should work through the apcupsd,
> or is this failure to be expected?  I guess I can run self test from the
> front panel and see if apcupsd then recognizes it.
>
> Regards,