Protecting my home equipment with the APC Back-UPS 850VA


With more and more electronic devices present in the home you might be considering having a UPS (Uninterruptable Power Supply) to protect them from sudden power loss. Even when you have a reliable supply of power, there is always the chance of “brownouts” or momentary power loss where the voltage drops enough for devices to lose power even for a second. This is bad for devices like PCs, home servers and the like.

Most recently I experienced two low voltage power events that knocked out the power in my home very briefly, the second one I was just in the middle of pressing buy on a couple of APC Back-UPS 850VA units (irony!). If I ever needed a sign of should I purchase a UPS, that was it! It is a concern however for always on devices like home servers, routers, PCs etc, having the power removed suddenly isn’t healthy long term.

I chose two APC Back-UPS 850VA units from Schneider Electric. They are rated for a max of 520W load (converting 850VA to Watts), offering a total of 8 power outlets, 6 battery backed power outlets with the remaining two just surge protected. The battery is also serviceable so it can be replaced. The max load and battery power outlets were key for me as I’m protecting a fair bit of equipment. The 850VA model provides the balance on being able to handle a decent load with a good amount of battery backed power outlets available that’s affordable for consumer use.

Equipment running on my UPS

For the first UPS unit I am running the following:

  • 1x HP Microserver Gen8
  • 1x HP Microserver Gen10
  • 1x Linksys WRT3200ACM router (OpenWrt)
  • 1x Arris Modem for my DOCSIS cable internet line (Virgin Media)
  • 1x Draytek Vigor 130 VDSL modem (backup internet connection)
  • 1x TP-Link SG-1016 16 port switch

This covers my core networking gear in the event of power loss.

For the second UPS unit I am running the following:

  • 1x Custom desktop PC
  • 2x Dell Monitors
  • 1x Speakers/subwoofer
  • 1x TP Link unmanaged switch
  • 1x Mac Mini (Late 2012)

This covers my main home office equipment.

When protecting equipment like a desktop PC it is always important to remember the peripherals! I’ve read a few stories about those who have invested in a UPS but forgot to put their monitors on one! Oops.

Calculating the average load

The key factor around a UPS is the load you are putting on it. The main devices that will draw the most power are my HP Microservers for the first UPS and and my desktop PC for the other UPS everything else is fairly low on watts consumption. The HP Microserver Gen8 and Gen10 have a 200W power supply, my desktop PC has a 550W power supply. You might be thinking how is the UPS going to work with devices like this taking up most or even exceeding the max load already? Well, on average devices won’t be using their entire rated power supply capacity most of the time if ever. The best way to know what the actual average power draw is plugging your devices into a power metre and measuring for a period of time. Luckily in the case of HP Microservers, the community has done various benchmarks on this that provides an average and it’s no where near close to the max. Likewise with my desktop PC, the power supply will likely not be using 550W constantly unless perhaps the processor was pinned at 100% using all 6 cores from my Intel i5-9600K, but again unlikely. So the average load is going to be much lower.

Of course, the sustained load is still a factor and based on what I’m using, I would average that the UPS can only power everything for a perhaps 4–5 minutes on a healthy battery, but this is fine for my needs. The other main purpose of a UPS is designed to keep power going so it isn’t suddenly removed but to also shutdown equipment gracefully before the battery is depleted.

Automatic shutdown feature

Various APC UPS models support battery sensing this through a non standard RJ45 to USB data cable and the APC PowerChute software, but here comes a bit of catch with APC. Looking at various reviews and sources before purchasing, APC no longer supply this cable with some UPS units. You now have to go to and request one! This is a bit of strange move. In the provided instruction manual that comes with the unit, it is cited as a “environmental decision”, however this is a bit of con in my opinion. A pretty critical feature of this UPS is now not available out of the box because of the lack of this cable.

This cable also seems to have had a bit of stock issue from APC themselves a lot of the time and purchasing this cable from other sources isn’t exactly cheap either. Although there is a reasonable alternative from StarTech, possibly proof that APC are seriously overcharging on their data cable. However fortunately, APC sent out two cables to my address within one business day and they arrived through UPS (nice) just two days later.

I was also researching what the options are for shutting down multiple devices in the event of the UPS running on battery for more than a few minutes. The UPS itself only has one data port for this. Based on what I can find (because I don’t have the data cable to test yet!) it sounds like the business edition of the PowerChute software supports scripting and potentially means I can have a device that’s connected via the data cable send remote commands to other machines if needed. I haven’t verified this yet, as I can’t even run the software without the data cable, but I hope to be able to experiment with that soon. My goal is to run the PowerChute software on one of my servers, which can then issue remote commands accordingly to other systems if it is likely that mains power will not be restored within a few minutes.

The acid test… Pull the power!

Obviously a UPS can only really prove itself when there is no power. I could wait for a real power outage but that’s probably going to take a while, so we’ll simulate one instead by turning the power off at the socket (highly scientific right?!). You’ll want to make sure that the battery LED is showing a good status and full charge before doing this. Flick the mains switch off and… Nothing happens. That’s a good thing. Seeing things still powered on despite the mains off shouldn’t be surprising but it still kind of is. There is a click noise when the UPS switches to battery power with an LED notification and you do get an audible alarm on these APC units once the UPS is running on battery which thankfully can be silenced. I can imagine the situation if the power goes out at 2 AM and while your electronics are safe, your mood isn’t, being woken up by UPS alarms. Although to be fair, when the power does go out, a lot of neighbourhoods house alarms go off because the battery backup in those rarely ever gets serviced and can’t hold a charge anymore to keep the alarm system going. Fun fact, anyone’s house alarm that goes off during a power outage means they haven’t had their alarm serviced in a while or ever.

Overall the APC Back-UPS 850VA seems like a good UPS product for the home consumer that’s reasonably affordable. It protects my most critical equipment and I’m now protected from low voltage events that cause split second power loss with enough battery capacity available to automatically shutdown devices (when I can get the cable!). It is a bit of a let down regarding the availability of the data cable, but I hope there’s stock available so this can be sent out to me soon!

I'm a web developer, but also like writing about technical networking and security related topics, because I'm a massive nerd!