Another case where batteries won't charge, but system has been in use for over a year

whisperingsage
whisperingsage Registered Users Posts: 2
There was one person getting info on her RV with 4 panels, and her batteries wouldn't charge. The first part showed that the folks that answered thought it was possible her batteries were not deep cycle but car starting type.
I have a very similar situation, and it will probably be a different answer. In my case, we have been running a 5 battery bank of Walmart marine batteries about 95 amp hours each. !2 volt parallel wired. Last summer we were able to run our 115 VAC deep well pump for about 2 hrs a day, We had the 5 battery bank, but of course only ran it while the sun shone. We have an Outback flex 60,at the time our PV consisted of 970 watts and peaked at 25 amps in according the the Outback readout. I turned all other fixtures off when running the pump. According to the paperwork, the pump surges at 3000 watts and the constant watt needs is 1800 watts. When I run it, the Outback shows the volts out to be .647 and thereabouts. It seems to be able to handle the 3000 watt surge. The inverter is a 3000-6000 watt 12 vdc to 120 watt AC, have tested its output with tester. It is a Harbor Freight cheapo, which has worked longer than the 5 inverters we had before it. (at least a year).
This week we added 950 watts, running 2 awg size copper wire, they should have added 25 more amps, (the goal being that we can run motly off current sun power rather than battery power, leaving the batteries for night use) but the Outback is still showing just 25 amps coming in. When i check the wires with a clamp tester, it looks like 50 amps coming in, and as the Outback is 60 amps, that should be fine, but it appears that the Outback may be preventing it all from coming in.
When we tried running the well pump on the new power, (total about 1950 watts) the first day it ran about 10 minutes and turned itself off- i let it rest 30 minutes, then I could run it again 30 more minutes- enough to fill the 350 gallon tank and then have a little over for pressure.I was able to run it in spurts like this a few times over the day.
The next day It would surge and stop, surge and stop, all day,.It would never run.(I turn it on with a simple manual switch) So we are back to the gas generator for pumping water. Boy is this ever frustrating!
For the rest of our usages, no stove, computers are about 200 watts max (laptops,) the TV is 280 watts, the lights are 100-200 watts max, with all on at the same time. *Usually about less than 100 watts at a time. We heat with wood. I would like to hook the fridge up someday. We have been fridgeless for at least a year now. I know it should be able to handle a washing machine.
Last year the batteries held enough of *charge to keep the lights working during the night- not that we kept them on but that we could use them at night when going to the restroom. And use them when getting up early for work.
We are completely off grid, have been for 16 years.
But now that we added the new panels, the batteries are acting like they aren't holding a charge at all. They run the 4 watt christmas lights that we use for light for only an hour or two after nightfall.

I was hoping to keep adding to the system and for higher usage items, like a fridge (also saw an article where a young man added extra insulation on the exterior of the fridge and above the compressor and reduced his compressor cycling by 30%) *getting a separate system with the miniinverters on them and maybe a separate battery bank- but until we can resolve this problem, I can't begin to seriously do that yet.
What am i doing wrong?
My husband is depending on me to figure it all out as this is "my thing" and not his area of interest.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Another case where batteires won't charge, but system has been in use for over a yea

    Welcome to the forum (officially). :D

    Well let's see. 12 Volt system with five batteries in parallel? There's the first problem. It is highly probable that the batteries are 'laddered' in their connections and so will not share current evenly. This means one or two do most of the work and the others just die slowly. Here's some wiring diagrams for batteries in parallel: http://www.smartgauge.co.uk/batt_con.html
    If the ones you have are wired like method #1 that's a problem. Method #2 is better, and #3 is best. Most people can't get #4 right so it isn't worth trying. This is why we advocate fewer, but higher capacity batteries to get the power.

    Second those Marine/RV batteries are a notorious compromise, which is a way of saying they don't work well at either deep cycle or starting (at least not for long). If they are not sealed type you can get a hydrometer and check the specific gravity of each cell in every battery. I would expect to see some significant differences.

    Supposedly you would have 5 * 95 Amps hours or 475 Amp hours total. A pump hitting 3kW on the 120 VAC side will pull about 140 Amps from 12 VDC. In theory that large a battery bank should be able to handle that sudden demand. If the batteries are low or wired incorrectly or the wiring is small there could be problems there.

    You would probably be better off with four 220 Amp hour 6 Volt GC2 type batteries wired as two parallel strings of two in series for 440 Amp hours @ 12 Volts.

    970 Watts should be more than adequate for such a battery bank, and in fact would 'max out' an MX60 or FM60 controller.

    If at all possible moving to a 24 Volt system would be a significant improvement.

    I'm not certain what you have for equipment exactly, but if you could provide specs for panels/controller/inverter/batteries we can be more precise in advice. For example added panels may not be compatible with previous panels.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: Another case where batteires won't charge, but system has been in use for over a yea

    Something is hinky with the math as well.

    970 watts of array(solar panels) should bring in around 40 amps on a warm sunny day, all things considered. They could bring in around 60 amps on a perfect day. 970watts/17.5volts=@55amps.

    Indeed with the additional panels you have a charging potential of @110 amps(at 12 volts) you would want a battery bank nearly 1000amphour or potentially have too high a charging rate.

    Looks like you have some substantial loads, I'd switch to a 24 volt system, or even a 48v system if you might end up having even larger demands. Save the money that you should spend now on an additional charge controller and spend it on a new inverter. Might as well look into a true sine wave inverter too, since the modified sine wave is stressing your pump, making the motor run hotter and shortening it's life span.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Another case where batteries won't charge, but system has been in use for over a yea

    Have you ever checked those batteries for balance? Was each one individually charged prior to wiring them up in your final configuration?

    If one is going bad, or the bank is out of balance, they are all suffering.
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    Re: Another case where batteires won't charge, but system has been in use for over a yea

    Sorry to have to say it, but youve got quite a bit of homework ahead of you, if you want to avoid hiring an installer to fix up that system. Im not really sure what it is about renewable energy, but while a person may not hesitate to hire a plumber, mechanic, or electrician, but when it comes to RE, so many people think that it ought to be easy... and give it a go. Well, RE systems are as dangerous, actually more dangerous than grid power.

    As mentioned above, the original system wasnt the best, and trying to add to it, somewhat willy nilly, isnt going to help at all. Time to do a stock take. Itemise everything you have, get all the gear brands and specs, type up your load budget, and come back to us. Then we'll try to sort you out!
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Another case where batteries won't charge, but system has been in use for over a yea
    .... saw an article where a young man added extra insulation on the exterior of the fridge and above the compressor and reduced his compressor cycling by 30%) .....

    Be very careful. While the fridge is running (compressor running, not merely plugged in) feel the outside casing of the fridge. If it all feels cool, great. If you feel any warm spots, your appliance has coils under the metal skin, and that's where it sends the heat, as it cools the food. If you insulate the heat exchanger (outside cabinet), you will shortly be cooking food in your new oven.
    Powerfab top of pole PV mount | 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 ,

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: Another case where batteries won't charge, but system has been in use for over a yea
    but the Outback is still showing just 25 amps coming in. When i check the wires with a clamp tester, it looks like 50 amps coming in, and as the Outback is 60 amps, that should be fine, but it appears that the Outback may be preventing it all from coming in.

    Charge controller current (amperage) ratings are based on the output, not the input. Your controller (same as mine) can output 60 amps. If your battery is at 12 volts when you start to charge it, the max power the flexmax can handle is 12 volts X 60 amps = 720 watts.

    Your controller could handle twice the wattage if you use it with a 24 volt battery (60 amps X 24 volts).

    You do have a number of issues, as have been mentioned. Probably the most serious issue is the batteries (as Cariboocoot has explained). Short discussion of parallel batteries: http://www.wind-sun.com/ForumVB/showthread.php?14674

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i