Image Map Image Map
Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: UPS (power backup) schemes.

  1. #1
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    35,109
    Blog Entries
    18

    Default UPS (power backup) schemes.

    My current home setup for internet uses, on the front end, a VDSL2 modem, a router to distribute the bits that also implements a Wifi AP. I have a VoIP adapter connected to one of the ports on the router and mail service is furnished by an Orange Pi PC (Chinese RPi).

    I've been powering the things alternately through a bit Elgar (1500W) UPS or a smaller NSSI 450W UPS. Both are overkill for the job and floating AGM SLA cells on the thing eventually causes them to sulfate up or dehydrate.

    Now, I could probably power the rig directly from 12VDC, dropping the 12V as needed to 5VDC using a small buck converter. But what would be my ultimate power source?

    How do Li-ion batteries perform if they're floated for years? The number of discharge cycles could be counted on the fingers of one hand per year.

    LiFePO₄ might be a great solution, but they are very pricey.

    Suggestions? Maybe a wet-cell car battery on float?

  2. #2
    Join Date
    Apr 2010
    Location
    Albany, OR USA
    Posts
    980
    Blog Entries
    1

    Default

    Two golf cart batteries in series is what the serious RVers like for dry camping. They last a long time and have lots of space for water. You need a good quality float charger like a battery tender to maintain 'em. Check the water level every month or two and that's probably more frequent than needed.

  3. #3
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    35,109
    Blog Entries
    18

    Default

    Why in series? 12V should be sufficient for my needs. I do have a pair of garden tractor batteries sitting on my front porch that are charged off a couple of PV panels. I keep them filled and after 4 years, they still seem to be holding their own.

  4. #4
    Join Date
    Apr 2010
    Location
    Albany, OR USA
    Posts
    980
    Blog Entries
    1

    Default

    Quote Originally Posted by Chuck(G) View Post
    Why in series? 12V should be sufficient for my needs.
    'Cause there 6V! And they are HEAVY! Lots of lead and acid in those.

  5. #5
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    35,109
    Blog Entries
    18

    Default

    To supply <30W on demand? Seems like serious overkill.

  6. #6

    Default

    I run most of my house (sans air conditioning, 240v deep well pump, and washer and dryer) off a bank of 8 T-105 golf cart batteries (wired as two parallel banks of 24v), charged by a Noco G26000 bulk/float charger, and 120v supplied by a 2000w Samlex inverter. The idea was to eventually install solar panels on the roof and only use the Noco when it was too cloudy for too long, but I haven't gotten 'round to that phase of the project yet.

    Anyway, the batteries are around 6 years old now and still doing fine, though they very seldom get cycled very deeply at all.

    You could probably build something scaled back with two batteries and a smaller inverter. I think the most important thing is to have a good bulk/float charger. But yeah, I've been quite happy with the golf cart batteries, and they were far cheaper than batteries specifically designed for these sorts of uses. They don't surge as well as the giant UPS batteries we used to use in the great big outdoor fiber cabinets, but they've been more than sufficient for my purposes.

    Edit: As with any wet cell, they release hydrogen when charging, so you want adequate ventilation.
    Last edited by bladamson; September 16th, 2020 at 05:30 PM.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  7. #7
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    35,109
    Blog Entries
    18

    Default

    We tend to get power outages here during winter storms--maybe about one every 2 years. Fortunately, the substation is only about a half-mile up the road, so we generally get pretty prompt service.

    The past week and a half has been an exception--no outages because of stuff taking the lines down, but rather a proactive shutdown to avoid starting fires. You'd think that the folks with solar would be sitting fat and happy, but you'd be wrong. The heavy smoke in the air caused the whole day to look like twilight--no sun. So they were just as desperate. On a few days, we were getting only about 5 hours of power. Caught me in the shower twice.

    My good old NSSI UPS ran for a bit, but gave up the ghost only about a half-hour in. Batteries were sulfated and not taking a charge--and they were only 2 years old--all of the UPS SLA AGM batteries come from China nowadays and you get what you'd expect.

    I keep a set of garden tractor 12V batteries on the front porch with a solar charger--puts out about 100 ma on most days, which is enough to keep the batteries charged. Next time, I'm going just haul that battery box inside and hook up my inverter.

    Those T-105 cart batteries seem to be about $200 the each, which is more than I want to spend on this. It'd be cheaper to go down to Hazard Fright and buy a gas-powered generator.

  8. #8

    Default

    Forget lead acid batteries. I went through 3 sets of them every 2 years in my tornado shelter. They don't last. What did last? A guy was selling some car sized 12V sealed AGM cells that were cycled out of a cell tower for $75 each. A pair of them has been down there for 10+ years and are still going.

    I've got a similar issue as you - wiring panel with modem, router, switch. I've been running it on a small UPS using a 12V 8AH SLA and just replace it every few years.

    If you go with a small generator, get an inverter based one. They can slow the RPM and burn less fuel when the load is light.

  9. #9
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    35,109
    Blog Entries
    18

    Default

    My suspicion is that my UPS is over-charging the 3x6v AGMs, leading to their shortened lifetime. That's what's odd--it takes an 18V battery configuration. My 1.5KW Elgar uses a 48V battery setup and is entirely too large for the application. It's a beast. If I could get 5-7 years out of some AGMs, I'd consider it.

    There's a guy selling the CyberPower 1500 UPS for $60 the each. I suspect that I'd be replacing the batteries in those things every couple of years too.

  10. #10
    Join Date
    Sep 2003
    Location
    Ohio/USA
    Posts
    8,092
    Blog Entries
    2

    Default

    I would say get a generator if you are going to be having blackouts that last for hours or days (good luck finding one now). UPS generally are only needed when you have shitty power coming in (voltages vary widely and/or spike) and for momentary power loss from circuit breakers going off.

    Modern car batteries seem to be junk these days as they will go bad sitting around a year or two. UPS batteries seem to be even worse.
    What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
    Nubus/ISA/VLB/MCA/EISA cards of all types
    Boxed apps and games for the above systems
    Analog video capture cards/software and complete systems

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •