Testing the backup time for a cheap (DC) UPS for a Plusnet Router and a Cisco ATA

[#1]

Ok, so there is theoretical discussions elsewhere about what UPS you need and so on, to provide power to run a router and an ATA (the VOIP telephone interface box).

I recently bought a simple DC UPS from AliExpress for under £30, it's a model "DC1036P". It is allegedly a 10400mAh device (I guess they are using 4 x 2600 mAh batteries... 🙂 ). It has a standard 2-pin mains inlet, and multiple power outlets: on a set of 3  5.5/2.5mm connectors there is 5v, 9v and 12v. There is also a USB outlet (5v), and mine also has a PoE port (selectable 15/24 volts). It comes with 2 DC power cables (not QUITE as useful as you might hope!)

(You can also buy these from eBay, maybe £40 or so)

Warning: there are 2 major versions of these devices: the "normal" one is only rated as 18 watts... PROBABLY NOT ENOUGH! I specifically bought the 36 watt version.

The BIG question: how long will it provide backup for a router and an ATA?

So, my long-term plan is to move to fibre / SOGEA, and use VOIP. To do this, I have bought a Cisco SPA122 cheaply on eBay: this allows the use of up to 2 telephones to connect via ethernet to VOIP services - I'll only need to use one of them. There's several of these devices available, for example Grandstream make suitable units.

This device runs from 5 volts, and it has a 5.5/2.1mm power socket: good news the 5.5/2.5mm cable supplied with the uPS works fine! In "standby" mode, it uses just over 1 watt, and a bit more if the phone is in use.

The ATA (Analogue Telephone Adapter) will allow me (using a suitable cable that I will make) to connect my home telephone wiring to a new VOIP service.

For the router, I'll use the Plusnet Hub2, but for testing, I am using one of several Hub 1's I have: I'm just looking for a "rough time before battery expires" at the moment, so the fact that the HUB probably takes a bit more power isn't a big issue. Both hubs use the same PSU, so can't be THAT different.

The first problem is that the Hub1 and the Hub2 both use a very non-standard size of power plug: my solution to that was to buy a 5.5/2.5mm plug and socket. I then cut the router power cable in half, inserting the pair of connectors in the middle... that way I can still use the PSU, but the router can also be plugged into the UPS!

Ok, so the test environment is very simple, but probably "close enough" to a real set-up for the results to be "close enough":

1) UPS has been fully charged, and running the ATA for a couple of weeks now.. so nicely tested with a small load

2) HUB1 is NOT connected to broadband, just sat in the desktop, lights flashing! 

3) The ATA is configured and connected by an external network connection to a live VOIP service

4) So, plug in the router & ATA to the UPS, let them boot up, then simply unplug the mains and wait!

Performance?

- I started the test over 2 hours ago, and the UPS is STILL showing 50% capacity

- The UPS is actually running COOLER than when on mains (makes sense, as it's only using HALF the electronics, it's not having to charge the batteries.

- Apparently NO issues caused by switching the mains on an off

I need to measure the power consumption of both the Hub1 and Hub2, to see what they REALLY use!

[#2]

Moderator's note:
Thread moved from Home Phone to Tech Help

[#3]

An update:

- After 3 hours it was at 25%... I went and did something else, by the time I returned, a couple of hours later, all was dead - no big surprise. So I'll guess at a run time of 3 to 4 hours, with both router and ATA running.

- I just measured the current used by the router - wifi enabled, broadband NOT connected - and it was just under 500mA, at 12 volts... which makes approx 6 watts. Add this to the 2 watts of the ATA, and my total is 8 watts: I could easily have got an 18 watt unit.

(So, clearly the mains power brick, rated at 1500mA @ 12v is well under-utilised!)

So, to answer the question: The BIG question: how long will it provide backup for a router and an ATA? Looks to be in excess of 3 hours, which I would say is very acceptable! And definitely the way to go, compared to using a mains UPS.

POE

One thing I ignored, as it is not relevant for me, was the POE port. My unit came with this, so this could be good for someone who needs POE for a camera. 

Clearly, the more you power from the unit (ups to it's 36 Watts maximum) the shorter it will last under battery, but it would definitely be useful for short power outages.

Central Equipment

Of course, all of this will only be of use if the "exchange equipment" continues to function during a power cut.

With FTTP, it will very much depend where they have the equipment, and what level of UPS protection they have. Traditionally, BT have had good backup capability.

For SOGEA, then the kit your router talks to is "out on the street", and even if it has a built-in UPS, it will be relatively small, maybe providing protection for a few minutes at most. 

The same discussion applies when you start saying "well, I can use my mobile phone"... how well are the masts protected against power outage?

[#4]

Interesting device thanks. 

Checked the maths using 'stored power' :

Taking your assumption of 4 x 2600mAh standard lithium Ion cells, those are 4.2V full

44Whr energy stored

So taking out 8W at 90% efficient gives you 4.8 hours.

Could be LiFePO4 (the very long life cells) at 3.6V (37Wh, so 4.2 hours).  I'd be a lot happier with those in the unit

[#5]

Whilst Ali Express sell naked PCB's for UPS use, not seeing any actual boxes without the cells. Mind you, at sub £30, you could just buy one with cells, and just replace them!