An alternative look at UPS requirements.

[#1]

One for discussion/comment.:

I read of concern regarding the limited time that an UPS will keep a phone line alive during a power cut. General thinking concentrates on treating the symptoms, that is, addressing the battery capacity, rather than the cause, that is, the power requirements.

A single channel ONT consumes about 2.5 W. The average router 10W and an ATA 1.5W (Grandstream HT501), that’s typically a total of 14W on a FTTP supply using a corded phone. By far the biggest load (over 70%) is the router.

Starting with the ATA, this can be removed by having a mobile phone with a contract that supports WiFi calling.

The Hub 2 gobbles 10W. I have looked for lower power consuming simple routers and come across this: https://www.gl-inet.com/products/gl-mt300n-v2/, which consumes <2.75W. As far as I can see, this is compatible with the ONT, be the wireless performance restrictive. TP-Link also sell a low power device.

So, with this router and a mobile phone with WiFi calling the load on the UPS would be reduced from 14W to 5.25W. This would extend the life of the UPS battery nearly threefold.

The UPS approach is also worth a rethink. Current practice seems to be based on a 12V battery jacked up to power a 240V ac inverter. Into this is plugged a combination of switched more power bricks to bring the voltage back down to 5/12V dc. There has to be a more efficient way to do this.

[#2]

There are a number of devices like this one Konnected UPS  that provide a 12v or 5v USB output, where a 12V battery is charged and then provide power without the inefficient change to 240v and back again...  as you imply the standard 240v UPS don't seem to last that long in a power cut... 

[#3]

Something to consider......   you quote the base supply as a  "12v Battery"....  to most, this would assume to be a 12v car battery, which I suggest, is the wrong type of battery for this kind of application.  Where a "Leisure Battery" would be better employed.

The "normal" type of 12v car battery is designed to give a high output on demand... i.e. the starter motor and turning over of the engine. along with the ignition if fuelled by petrol. 

A "Leisure battery"... also 12v... is designed to give a longer supply of power at a lower output. such as 12v internal lighting, and other 12v equipment, as used in the caravan and boating world.

It is worthwhile, to consider looking at sites that sell Leisure batteries, and take advice from the supplier(s) regarding their useage in this application.

As for the internet and telephone calls....  have a look at 4G LTE wifi router(s).... such as the TP-Link MR6500V Telephony.... The ZTE MF286  ( some have facility to use a replaceable 3.7v 3000mAh LION battery )   or the Huawei B535-235 or B535-333

You do not need a VOIP supplier to run your "normal" BT type plug in phone with these routers... as you will be using the "mobile phone" number supplied with the SIM card of your choice.

Of course. your internet speed will be governed by the amount of "traffic" on any particular cell mast that you are connected to. but your calls will be free !. and no VOIP monthly charge.

[#4]

You do not need a VOIP supplier to run your "normal" BT type plug in phone with these routers... as you will be using the "mobile phone" number supplied with the SIM card of your choice.

Most of this concern is from people concerned about the impending (2025, possibly postponed to 2027) withdrawal of the '"normal" BR type plug in phone' service altogether. The only replacement for that, if you want to keep your landline number, will be VoIP - which has nothing to do with SIM cards.

(The basic point that routers with lower power consumption exist is, arguably, a good one.)

I can see a market arising for backup devices that have low-voltage outputs. I've seen ones that in effect replace the router power brick, but actually contain a battery; however, I think most routers require 12V, whereas most ATAs (and I suspect VoIP 'phones) seem to have a USB power input, which is 5V, so two such devices are required, which is a pain.

[#5]

@G6JPG-0 says:  I've seen ones that in effect replace the router power brick, but actually contain a battery 

Yes I say those a couple of years ago, there are a number of "UPS" devices on Amazon that work off a 12v supply (from a power brick) and plug in between the power supply and the device... some supply a number of different voltages (12v, 9v and 5v USB) I guess this Eaton  is fairly well known  or this Konnected seems to be sold by a US alarm manufacturer with an outlet in the UK.   Most of the rest appear to be far eastern companies, not sure what testing/certification they have been through and I'd be a bit wary of plugging those in permanently at home.

I agree these type of 12v/5v UPS devices ought to become much more common to protect the ONT/Router and any VOIP equipment... at least with FTTP the signal should remain during a power cut - which probably isn't the case with FTTC or ADSL.

[#6]

There used to be a device branded "Elmdene" that went between the DC "Brick" and the thing being powered and it would automatically determine what voltage to use, sadly that one's long been discontinued.

It would be useful if manufacturers gave clearer information on their input voltage specification. A lot of devices are nominally 12V, but some are designated as accepting 12-15V so they should run off of a nominally 12V lead acid battery without needing additional regulation. The ones marked 12V will probably accept the battery but there's no guarantee.

Incidentally I'm not certain of this but I seem to recall that at the cheaper end of UPS units the inverter is inadequately cooled so it is thermally time-limited and might be cutting out early even though there's still charge left in the battery.

[#7]

This document https://www.openreach.co.uk/cpportal/content/dam/cpportal/public/images-and-documents/home/help-and-... page 27 tells us that the ONT supply tolerance is 11-14 V. So by adding a 12V to USB 5V charging adapter as available for cars and a bit of wiring bodging it’s perfectly practicable to provide a low power wireless Internet connection using a mobile router powered by a float charged 12V battery with reasonable capacity. This could keep going during the day for days, not an hour or so. Options for keeping the battery topped up include using solar or piggy backing on a car battery.