Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: 12V DC Mini-UPS  (Read 2035 times)

jack21

  • Reg Member
  • ***
  • Posts: 129
12V DC Mini-UPS
« on: March 11, 2016, 05:40:16 PM »

I've had a pre-owned Belkin Pro Gold 325 UPS for over a year now, powering my modem/router, Raspberry Pi and electricity monitor very satisfactorily.....it has seen the kit through several small electricity outages, including huge electrical storms, and I've never had a broadband connection loss due to power. I've not yet even had to put a new battery in it. It sits unobtrusively, humming away fairly quietly, and I'm very pleased with it.

But I've always thought that converting the battery-supplied 12V DC to 230V AC only to then have to use an  adapter to get it back to 12V DC is wasteful to some degree, so I've been keeping my eye open for a genuine 12V DC UPS - seemingly quite common in the US, but not so common (or cheap) in the UK. Anyway, this week I spotted a 52V DC UPS on eBay, very cheap (details below), and I happened to have a spare 12V battery to use for experiments. Bit diasappointed that it wasn't the 12V model, but hey-ho! So I ordered the UPS, and a step-down board to get from 52V to 12V.....altogether, 16 incl P&P. Today I set it all up (I had to do a bit of soldering connections to the step-down board, and got through that OK) and set it in action......works a treat.

It runs virtually silently, outputs 12V DC exactly (easily tuned) and does not waste much power/heat in doing the step-down. Overall, slowly charging the battery and running a (spare) router it uses 13W. I haven't yet put my 'live' modem/router on it - I don't want to drop connection at the moment - but I will switch my Billion onto it at the first appropriate chance.  It switches from mains to battery when appropriate, and no hiccups doing so.  OK, it doesn't have the alerts/alarms that are usual in modern UPS - just 3 LEDs - but it does have 'signal' outputs which could be utilised if needed. So a nice little mini-UPS capable of running a modem/router for several hours for just 16, an old battery, and a pleasant bit of practical work.

UPS     http://www.ebay.co.uk/itm/321499325710
Board  http://www.ebay.co.uk/itm/271998726229
« Last Edit: March 14, 2016, 10:52:43 AM by jack21 »
Logged

Starman

  • Reg Member
  • ***
  • Posts: 158
Re: 12V DC UPS
« Reply #1 on: March 13, 2016, 07:44:01 AM »

Interesting UPS - how do you connect the UPS to the router itself tho - I'm assuming it doesn't have a normal 3pin socket.
Logged

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC UPS
« Reply #2 on: March 13, 2016, 09:05:53 AM »

Re connecting UPS to router:

There's a connector block under the front battery-access panel, which includes 2 connections for its output. I attached 2 wires to feed the very small step-down board, then took the 2 outputs from the board to a new grub-screw-type connector.......to which the router power supply is then connected using an old adapter cable with its cut end exposed, tidied-up and its 2 wires solder-coated (the other end with barrel connector plugs directly into the router). There's plenty of room for all that under the front panel.

« Last Edit: March 13, 2016, 09:21:05 AM by jack21 »
Logged

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC Mini-UPS
« Reply #3 on: March 23, 2016, 10:48:22 AM »

Update:

I put my Billion 8800NL on the mini-UPS, connected directly to the UPS without the usual adapter. I was very pleased with the performance of the router.......the SNRM trace was much 'cleaner' (free of any up or down spikes at all), and the error rates decreased a little.

BUT after 5 days of perfect performance a worrying thing began to happen .....I found the Billion self-rebooted, at first roughly once a day, increasing to 2 or 3 times a day.  I suspected either the UPS or, perhaps more likely, the cheap voltage step-down board, not keeping to the intended voltages at all times,  and I've now got the Billion back on the regular Belkin UPS and with its 12v regulated adapter back in play. I hope that stops the self-reboots!

I've no means of checking the sustained voltage stability of the mini-UPS plus step-down board, so I've abandoned the experiment.
Logged

Ronski

  • Helpful
  • Kitizen
  • *
  • Posts: 2015
Re: 12V DC Mini-UPS
« Reply #4 on: March 25, 2016, 10:19:24 AM »

I noticed the step down board had quite a low power rating of a maximum 15W, it's quite possible it simply couldn't handle the sustained load.
Logged

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC Mini-UPS
« Reply #5 on: March 25, 2016, 11:29:30 AM »

Yes, Ronski, that was my conclusion too. Most of the time the router/step-down/ups ticked along at around 9 watts measured at the mains socket, but I did see briefish increases to 13/15W when watching iPlayer, so I've speculated that at times, the board did an overload cut-off. Since moving away from that board, the Billion has not misbehaved.

I have ordered a  50W step-down board (rated at 38V max input), but this time I'll be using it with a  high-quality 15 or 19V laptop adapter to get it down to 12V.......expected arrival 3 weeks. Obtaining a 52V>12V step down of 15W+ rating is a bit pricey for experimentation purposes, but I will keep a weather eye on possibilities, because I would like to return to the mini-UPS in the future, if possible.
[later update: I've now spotted a higher-rated board of  75W at acceptable price and will give that a try]

In the meantime, I'm powering my Billion with a largish (laptop-style)  230V>12V  5A regulated power supply that I have used to power one of my 12V mini-ITX computers very happily over several days via my normal UPS without issue. When I swapped the Billion away from its wall-wart 12V 2A adapter I immediately noticed a  'cleaner', minispike-free SNRM trace and somewhat lower error rates on up/down stream. I guess the psu is of higher quality than the wall-wart type.
« Last Edit: March 26, 2016, 08:37:39 AM by jack21 »
Logged

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC Mini-UPS
« Reply #6 on: April 20, 2016, 08:49:45 PM »

Update:

The 12V 5A switching-type adapter mentioned in my previous post powered my router for 2 weeks very satisfactorily.....a 'clean' SNRM trace, minimal errors (compared to old wall-wart type), and router behaved perfectly.

I then powered my router with a 19v dc non-switching laptop adapter feeding a voltage-adjustable board with a 50+ watt rating (cost 1), and that too worked as well as the 12V 5A adapter; very acceptable and better than wall-warts.

The higher-rated 52V>12V buck converter (100+ watts) eventually arrived.....cost was 8
http://www.ebay.co.uk/itm/DC-8v-55v-to-DC1v-35v-12v15A-Adjustable-Buck-Module-Step-Down-Voltage-Regulator-/231769262129?hash=item35f6864831:g:vLMAAOSw8-tWWs6F
........and I set the router to be powered by the mini-UPS linked via the buck converter.  The SNRM trace was clean, as per the 2 methods above, and the CRC and ES error rates were even lower than previous methods.   That's how I'm now settled with running the router from now on.

All these tests did show, at least in this case, that the SMPS wall-warts (I tried 2 different ones) did not produce as favourable results as the other methods I tried.

And the mini-UPS project cost me just 24 for parts for a very useful bit of kit to power and protect my router (and broadband connection) against voltage instability/spikes and mains drop-outs.


« Last Edit: April 21, 2016, 11:09:52 AM by jack21 »
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 18567
  • Over the Rainbow
    • The ELRepo Project
Re: 12V DC Mini-UPS
« Reply #7 on: April 20, 2016, 09:31:41 PM »

Thank you for that update. Interesting results.

As you have not made any mention, I presume you do not have access to an oscilloscope. It would have been rather interesting if you could have obtained a trace for each different source's 12V DC output.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC Mini-UPS
« Reply #8 on: April 21, 2016, 07:26:14 AM »

@burakkucat
Yes, just basic kit here I'm afraid; simple Draper multimeter (dc volts/ohms) and a mains socket power meter (ac volts/amps/watts/freq).
Very limited soldering capability too!
Logged

jack21

  • Reg Member
  • ***
  • Posts: 129
Re: 12V DC Mini-UPS
« Reply #9 on: June 16, 2016, 01:55:49 PM »

I see that the kit is still available on eBay, and it has been working very well indeed for me; I've used it to power several different routers, and during this last week's thunderstorms and power blips, it has saved the day for my broadband several times.
« Last Edit: June 16, 2016, 03:59:44 PM by jack21 »
Logged