Small off-grid system for power outages

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  • gonavy27501
    Junior Member
    • Sep 2018
    • 4
    #1

    Small off-grid system for power outages

    I've been looking into building a small solar generator for a while now, and with the approach of Hurricane Florence, I got busy and started putting it together based on some I found on the internet. I won't go into the details because it's a great example of what not to do (besides the 2 6v FLA golf cart batteries wired in series, 215 aH).

    Now I'm looking at doing it right. I'm just looking for the correct components to provide some power to a 24"LED tv (33w on the high end, 20w nominal), charger some AA/AAA batteries for flashlights and radio, charge cell phones, run a small fan if possible, and maybe run the wifi router and charge a laptop if possible. These loads won't all be on at the same time. I plan on getting a DC/DC charger for the AA/AAA batteries, and have the specs for everything but the small fan. I tried running a fan off of a modified sine wave inverter and it showed problems right away (slower speed, I didn't wait for anything to get hot).

    Some of these components are strictly AC, some I can run DC/DC, and some are run off of AC/DC adapters. So I'm looking at a 1000W inverter or smaller, but I'm not sure about pure sine wave or not.

    I also have a couple of charger questions:

    1) Can 2 6v 215aH golf cart batteries be charged while wired in series all the time by a 12v charger (including equalization charge)?

    2) I've read about needing a "good" charger as opposed to a cheap consumer grade charger. It appears that I need to charge my batteries at ~ c/10, or 21.5 amps. I'm having trouble finding any cost-effective chargers that can deliver that to a 12v battery, much less a 6v battery (hence question 1).

    Any input will be greatly appreciated!
    Mike
    Tags: None
    • Jafo
      Member
      • Aug 2014
      • 54
      #2
      I can't help you with #1 or #2, but I will say that I found the modified sine worked when I ran the power through a good power strip. I know many will say it makes no difference, but it did for me. That being said, I eventually went with a 1,500 watt pure sine and have had zero issues unless you consider the extra cost an issue (which I guess I did).

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        • Mike90250
          Moderator
          • May 2009
          • 16020
          #3
          The vast opinion is, that if it's a motor or transformer based item, it needs pure sine wave.

          Your list of gear indicates to me, that you could use a much smaller inverter - something in the 300w class. battery chargers are 5-10 watts, along with phones. Fan is 50 - 100w, stay at a slower speed, and your battery lasts longer. Laptops vary from 40w - 120w, look at the label of the power adapter for a ballpark number. What is your wifi router going to talk to, or is it a local network - if grid power is down, the cable internet has a 6 hour battery on the phone poles, then the TV goes off.

          Batteries - a pair of 6v wired in series will charge like any other 12v 215ah battery, needing about 20a of charge current to keep it happy. Would this be solar, or from a battery charger running off a generator, or float charged off your household outlet before the grid goes away ?
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

            Comment

            • gonavy27501
              Junior Member
              • Sep 2018
              • 4
              #4
              Jafo and Mike, thanks for the replies!

              Mike - I am already leaning toward the PSW inverter because of what I've read so far. As far as the size, I wave a Kill-a watt meter on the way so I can get some exact figures.

              For charging, I will be topping the batteries off and recharging them with with grid power as much as possible. If the outage lasts long enough, I'll be charging with solar.

              Since the batteries should be charged from C/12 to C/18, with C/10 being optimal (per Sunking's sticky on Batteries), I'm looking at 17.92a > 21.5a > 26.88a for charging.

              Chargers: I've found this charger from Potek. It is a smart charger that also allows manually selecting the charging amps. Anyone ever heard of this company?

              https://www.amazon.com/dp/B01KF7SLJO...v_ov_lig_dp_it

              Specification:
              Rated input voltage: 120V AC/60Hz
              Input current: 4A
              Rated output voltage:12V DC
              Output current: 2/10/20 A
              Maximum output current: 20+-2a
              Maximum Charging voltage:14.8+-0.2V
              Floating charge voltage:13.6+-0.2V
              Dimension(L*W*H):10.1*8.3*5.6in
              Weight:3.9LB
              Ambient temperature:0 ~ 40
              Last edited by gonavy27501; 09-21-2018, 01:20 PM.

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