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Chilling_Silence
14-04-2014, 06:21 PM
So hypothetical situation here (Coz I don't understand power-math).

If I had this:
http://www.pbtech.co.nz/index.php?z=p&p=UPSBLZ00650

Power dies. It's only powering this:
http://pbtech.co.nz/index.php?z=p&p=NETTPL1043

How long would you expect it to run for before it dies?

Cheers


Chill.

Terry Porritt
14-04-2014, 07:32 PM
It isn't at all efficient (or cost effective) to use a UPS to power a router. It is using 12 v batteries and inverter to produce 230v, only for that voltage to be reduced down to 12v again via a power supply.

Consider using one or more 12v SLA batteries to power the router directly, and use a small multistage smart trickle charger to keep the batteries topped up.

Chilling_Silence
14-04-2014, 08:48 PM
I know it's not efficient but I don't have the time or know-how to build that kind of a rig. This is also multi-purpose :)

linw
14-04-2014, 08:55 PM
It's time that these devices were designed for standardised DC input. For UFB sites there is the ONT power as well. You really can't mess with that so that means a UPS.

Agreed that a UPS is ridiculous. Mine is so darned inefficient. Batteries are such a good idea.

decibel
14-04-2014, 09:33 PM
It's hard to tell exactly how much power is needed bythat router as the wi-fi will vary in its requirements but if you assume the worst possible case, allow 1.5A (which is what the external power supply is rated at)
The UPS - if you buy the cheap 240W unit which has a 4.5Ah battery and allow for only 50% inverter efficiency (it's a light load) then you should be good for at least 90 minutes.

As usual with these things, there's only one way to really tell - suck it and see.

Terry Porritt
14-04-2014, 09:40 PM
The 650VA UPS used one 12v 7AH battery. So the battery could deliver 0.35 amps for 20 hours (that what the AH rating is based on). The router power supply is rated at 1.5 amps, but the router will only take a fraction of this, so if we assume it consumes 0.35 amps, the battery will last around 20 hours x UPS efficiency x 12v power supply efficiency
The overall efficiency cannot be really be more than ~ 50%, so you could get up to 10 hours running time.

I use 3 x 12v 7AH SLAs to run an Orcon Genius router which gives me around 3 days of phones if there is an extended power cut.

Slankydudl
14-04-2014, 09:48 PM
Charge your batteries through the power coming on the phone line = free backup power.

ronyville
14-04-2014, 10:25 PM
I have this

http://www.pbtech.co.nz/index.php?z=p&p=UPSCPR01200&name=CyberPower-Value-1200ELCD-AU-1200VA-720W-Line-Inte

powering only my TP-Link TD-W8960N and cordless phone, just tested it in the weekend and the UPS lasted around 7 hrs.

Hope this helps.

dugimodo
14-04-2014, 11:29 PM
Charge your batteries through the power coming on the phone line = free backup power.

There's 50V across the line when it leaves the exchange, but there's very little current. It might be possible to use a very efficient charging circuit to trickle charge a small battery but it would never be a very good source of power.
You could use a small solar panel and a battery though if you want a free(ish) power source.

I'd use a watt meter to measure the actual power consumption of the router at the wall and then use that to figure out the run time myself. Just as a guess I'd expect it to run several hours. Many UPS's have a very annoying warning alarm when the power is off that can't always be disabled though, might be worse than losing the net for a few hours :)

I'd agree a 12V battery is a better option in many ways, but it doesn't come pre-built and ready to go. Jaycar do sell SLA batteries and chargers though, all you'd need to add is the appropriate power cable and make sure the charger supplies more current than the router uses.

My emergency power supply is somewhat cruder, I have one of those car Jump starters with a cigarette lighter and usb charging outlet and a cheap 350W invertor. If the power is off for any length of Time I can run one or two things off that. I find a household lamp with a 8-10W LED bulb is better emergency lighting than any candle or torch as well :)

Chilling_Silence
15-04-2014, 02:28 AM
Very interesting food for thought!

Thanks all :-)

Terry Porritt
15-04-2014, 08:53 AM
It is very easy to knock up a simple UPS to power a modem, all you need is a crimping tool and some connectors and some wire, and a lead to connect to the router. Anyone used to working around computers could do it.

Connect SLA batteries in parallel, get a proprietary smart charger. connect up...done. I also added a diode in the supply to the router to drop the voltage a tad, but not absolutely necessary. The second photo shows the charger, the grey thing with an orange light showing.

Chilling_Silence
15-04-2014, 12:20 PM
Nifty! :D

Cato
15-04-2014, 01:19 PM
So hypothetical situation here (Coz I don't understand power-math).

If I had this:
http://www.pbtech.co.nz/index.php?z=p&p=UPSBLZ00650

Power dies. It's only powering this:
http://pbtech.co.nz/index.php?z=p&p=NETTPL1043

How long would you expect it to run for before it dies?

Cheers


Chill.

You might run into another issue: some routers will turn themselves off on a very small load, like a router.

Chilling_Silence
15-04-2014, 01:23 PM
Some UPS's you mean ?

Cato
15-04-2014, 01:28 PM
Yes :)