Batteries not holding charge

rubbertreesolarrubbertreesolar Posts: 8Registered Users ✭✭
Hi all,

I have four Trojan T105's set up for a 12 V system. My set up is less than three months old, installed after Hurricane Irma (and we still have no power, so technically we are off-grid  :).  Both my inverter (Xantrex) and charge controller (ProStar 30) have low voltage protection which, they both shut down at around 50%. I have gotten the batteries low, but never to the point where the system shut down.

For the last week or so I have noticed that the batteries appear to run down rather quickly. I checked with a hydrometer and this showed in the red. I have just gotten a new generator, so yesterday I charged the batteries using a Charge It 20Amp AC charger . This took a few hours, and according the charger the batteries were at 45% at the start, but it managed to charge up to 100% and automatically shut off. However, the batteries are not holding and are drawing down fairly quickly and the hydrometer is still in the red. We are not living in the house at the moment and all that is on are a few LED lights overnight, nothing else.

My ProStar solar charger supposedly does an equalization cycle every 25 days, and I don't think this can be overridden to perform a manual equalization charge.

Have my batteries gone bad already???

Thanks for any assistance!

Robert
Three 160 W Solar Innova Green Technology (Spain) solar panels, Xantrex Pro 1800XM inverter, ProStar 30 charge controller, four Trojan t105 batteries (12V system), back up 4,800 watt diesel generator (which has just died....). Located in the Caribbean (direct hit Irma survivor!!!).  Just added a new 7,000 watt dual fuel genertor (Dec 1, 2017)

Comments

  • EstragonEstragon Posts: 2,436Registered Users ✭✭✭✭
    The symptoms you describe sort of suggest sulfatation. There are three factors that can lead to this; deep discharge (50% is pretty deep), letting the battery stay discharged for long periods, and high temperatures. Could some or all of these factors apply?

    I would start by measuring SG in all cells, and voltages of each 6v battery. Try charging the best 2 batteries on their own. If sulfated, they're likely all sulfated, but it's possible bad connections or whatever only damaged one pair.

    Most controllers have a dip switch or other means of doing a manual EQ. If possible, I would give that a shot too.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mcgivormcgivor Posts: 1,881Solar Expert ✭✭✭✭
    Without total loads it's hard to determine if the system is over taxed, 30A charging is small for a 12V system, if loads include a refrigerator, it would not be supprising that the batteries are showing signs of fatigue, if I were you I would disconnect all loads and concentrate on battery recovery. With SG readings in the red, a vague indication, charging would be the focus, yes it is possible to kill the batteries in such a short time, especially if the loads exceed the capacity of both the battery and the charging source. The state of charge can only be accurately measured by the SG, if the SG is not 1.270, or thereabouts they are not fully charged, you want to be in the green level of your hydrometer. Please concentrate on recovery.before it's too late, include all loads if you reply, this will help all to determine if your system is ballanced.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • rubbertreesolarrubbertreesolar Posts: 8Registered Users ✭✭
    Thanks for the responses.  As we are not living in the house at the moment all we have on overnight are three LED lightbulbs. During the day when panels at max, I sometimes run a small waterpump (1.2 Amps) and the poolpump (small Intex pump), and some lights in the house. No heavy loads, nothing exceeding maybe 4 Amps at the time. During peak hours the panels will put out between 15 and 20 amps.
    Three 160 W Solar Innova Green Technology (Spain) solar panels, Xantrex Pro 1800XM inverter, ProStar 30 charge controller, four Trojan t105 batteries (12V system), back up 4,800 watt diesel generator (which has just died....). Located in the Caribbean (direct hit Irma survivor!!!).  Just added a new 7,000 watt dual fuel genertor (Dec 1, 2017)
  • MichaelKMichaelK Posts: 75Registered Users ✭✭
    edited December 2017 #5
    Because you're using a PMW controller, you're not really fully utilizing your solar panels.  Your 160W solar panels become 100W solar panels because the batteries drag the voltage down to 12V.  To maximize the charge on your T-105 you need (225 AH) X (.125 charging rate) X (12V system voltage) X (2 12V strings) X (1.2 panel derating) =810watts. 

    If you doubled the number of solar panels you'd be on the high side of good.  Your controller has a 30 amp limit, so you can't add an adequate number of panels to keep the bank charged.

    If you switched to a MPPT controller the numbers are better, but you are still under paneled.  In the short term, you can try splitting the two 12V strings and charging each individual string to full charge.  If you got another 3 panels AND a MPPT controller, you'd have a better balanced, better performing system.
    15 Renogy 300w panels,  Midnight 200 CC, 8 Trojan L16 batteries, Schneider XW6848 NA inverter, AC-Delco 6000w gen.
  • softdownsoftdown Posts: 1,824Solar Expert ✭✭✭✭
    Thanks for the responses.  As we are not living in the house at the moment all we have on overnight are three LED lightbulbs. During the day when panels at max, I sometimes run a small waterpump (1.2 Amps) and the poolpump (small Intex pump), and some lights in the house. No heavy loads, nothing exceeding maybe 4 Amps at the time. During peak hours the panels will put out between 15 and 20 amps.
    "Small poolpump"? That is a bit like saying small train engine. Pool pumps are comparatively large pumps as pumps go. Unless we are missing something here...which is usually the case when problems present I think.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • PhotowhitPhotowhit Posts: 4,597Solar Expert ✭✭✭✭
    edited December 2017 #7
    Okay, first I went and checked, it appears that those panels are true 24 volt nominal panels with a VMP of 34.4! IMP of 4.66 amps. They may make other panels that are true 12 volt nominal panels, but it the ones I found linked below are NOT!

    LINK

    You have a 12 volt battery bank 2x2 (2 in series and 2 in parallel) for a 460 amp 12 volt system.

    I have zero problems using a PWM charge controller with proper voltage panels, but these are designed to charge a 24 volt system. PWM can only pass through the amperage presented and moderate the voltage. even if you panels are properly position, facing south with an angle + your latitude, you can only expect a bit less than the IMP and you will lose some of that to heat (mostly you lose voltage with heat, but you will have some diminished amperage).

    You have a total load of load of 2-3 LED lights. You didn't tell use the size, but I'll assume 9 watt (60 watt equivalent in incandescent) bulbs + 2 watts of inverter inefficiency (could be more at a low power draw) + 9 watts to maintain the inverter. Call the total load 30 watts. Do you turn off the lights during the day? So you have 30 x 24 if you don't for a 720 watt load.

    LINK

    I'd make a blind guess you can average 6 hours to your system (energy used/charging)  at @4.5 amps on a 12 volt system for about 27 amps input per day.

    The load at 720 watts at 12 volts represents 720/12=60 amp draw from the system.

    Looks like you have a system problem. If you turn the lights off during the day through a timer. It will reduce your load by about 300 watts, but you still aren't in good shape.

    Since you have the panels you could switch to a MPPT type charge controller, They aren't cheap, but Renolgy makes one for $200 that will help, you should get roughly double the output from the panels.

    https://www.renogy.com/rover-40-amp-mppt-solar-charge-controller/?gclid=CjwKCAiAmb7RBRATEiwA7kS8VDVbEoaVbnfxv6kbHud1XwEswqjtgg3Kz3DSgj4cvNDTztUqOFKTuhoC-R0QAvD_BwE

    It's only 40 amps, and Trojan recommends a 10% charging rate for their batteries and you have a 460 amphour battery bank. You would still be a bit under their recommendations, but you have a lot of sun generally. 

    You currently have 480 watts of panels, if you switch to an MPPT type charge controller you could expect about 480x.75 (NOCT value)/14v (charging current for 12 volt system= @25 amps charging current. I don't know if the Renolgy can be 'over paneled' but I'd try to add enough panels to max it out at near 40 amps.

    The good news it the T105's are great batteries, If you can do a corrective equalizing charge on them they should be able to come back to life for you with minimal loss of capacity.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • MichaelKMichaelK Posts: 75Registered Users ✭✭
    A couple of problems.  As photowhit mentioned, the 160W panels Innova is selling right now are actually 34.4Vmp, I also found another similarly named panel with a Vmp of 18.5 and 8.5amp.  Robert, can you clarify what voltage the solar panels are outputting?  An open circuit voltage would be fine.  You'll need a voltmeter for that.  Do you have one?  Alternatively, is there a paper label on the back of the panel with those numbers printed on it?

    I'm not quite sure what would physically happen if panels putting out 34 volts were hooked to a 12V battery.  Are two strings of T-105 a big enough load to drag voltage down to 13-14V, or is too high voltage potentially why the batteries are in bad shape?  A while ago I tried hooking the raw output of a YingLi panel to a bank of four T-105s, but the batteries were wired for 24V and the panel's output when wired to the bank was 29.5V.

    Robert, since your controller is 12/24V switchable, you might try rewiring your batteries for 24V and charging them with the 34.4V output if those are indeed 24V panels.  You'll have to disconnect your inverter and any other 12V load before you do that. 

    Still, the panels aren't putting out enough amps and you'll still need additional panels, but in the short term you can get them in a more appropriate charging position.
    (225 amphours) X (.125 high charging rate ) X (29.6V charging) X (1.25 panel derating)= 1040 watts
    (225 amphours) X (.08 low charging rate) X (29.6V charging) X (1.25 panel derating)= 660 watts
    Six of your panels are what's appropriate for your T-105s.

    One other note:  Trojan's recommended equilization charge for T105s is 16.2 volts, and the ProStar is set at 15.1, so the voltage is low for Trojans. 


    15 Renogy 300w panels,  Midnight 200 CC, 8 Trojan L16 batteries, Schneider XW6848 NA inverter, AC-Delco 6000w gen.
  • PhotowhitPhotowhit Posts: 4,597Solar Expert ✭✭✭✭
    I did finally make it to their site and they do make true 12 volt nominal solar panels. I would like to have it verified though as I couldn't find outside sources.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • rubbertreesolarrubbertreesolar Posts: 8Registered Users ✭✭
    Hi all thanks so much for the responses. I have to admit I bought this on a whim after having gone through a cat 5 super hurricane! The advise I received at the marine store probably was not very good.

    The panels are indeed 12 volt panels (vmpp 18.2 volts. ) I realize now that I should have gone with the mppt controller, which I will invest in and then start adding panels.

    I was not aware of the equalization voltage required for the Trojans. Is there any other way to manually equalize them?

    With regards to the pool pump, it is a small Intex pool pump which only draws 1.8 amps.

    Thanks!

    Robert
    Three 160 W Solar Innova Green Technology (Spain) solar panels, Xantrex Pro 1800XM inverter, ProStar 30 charge controller, four Trojan t105 batteries (12V system), back up 4,800 watt diesel generator (which has just died....). Located in the Caribbean (direct hit Irma survivor!!!).  Just added a new 7,000 watt dual fuel genertor (Dec 1, 2017)
  • MichaelKMichaelK Posts: 75Registered Users ✭✭

    I was not aware of the equalization voltage required for the Trojans. Is there any other way to manually equalize them?


    What you might try is bypassing the controller and wiring the panels directly to the batteries after they've been charged.  It's a bit risky, and you have to monitor the batteries in real time with a volt meter and hydrometer.  Here's the data sheet for your batteries.

    http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf

     I've never tried it myself but the neighbors have.  Maybe I could suggest connecting the batteries till the voltage reaches 16.2 or density gets to 1.275.  If you batteries are in bad shape, they may never reach those values.  I'm used to working with a more sophisticated controller, so I don't have any hands-on experience doing this.

    Good luck!



    15 Renogy 300w panels,  Midnight 200 CC, 8 Trojan L16 batteries, Schneider XW6848 NA inverter, AC-Delco 6000w gen.
  • PhotowhitPhotowhit Posts: 4,597Solar Expert ✭✭✭✭
    The panels are indeed 12 volt panels (vmpp 18.2 volts. ) I realize now that I should have gone with the mppt controller, which I will invest in and then start adding panels.
    This is a good thing, and you have an appropriate charger for your batteries. Would like to see one with a manual equalizing, but we can work with this and these panels.
    With regards to the pool pump, it is a small Intex pool pump which only draws 1.8 amps.
    That's is 1.8 amps at 120 volts! which is @216 watts, That is a very large load for a small system! Your 3 panels might make 16x3=480
    480 x .75= 360watts on a good day each hour within 2 hours of solar noon. 

    The 216 watt load + the inverter loses @30 watts = 250 watts will eat up about all of that! Running the pump at night? that is stored energy which costs another 15-20%.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • rubbertreesolarrubbertreesolar Posts: 8Registered Users ✭✭
    Thanks all! I know what to do.... this is a great site, you have all been very helpful. Keep it up! Will keep you posted.
    Three 160 W Solar Innova Green Technology (Spain) solar panels, Xantrex Pro 1800XM inverter, ProStar 30 charge controller, four Trojan t105 batteries (12V system), back up 4,800 watt diesel generator (which has just died....). Located in the Caribbean (direct hit Irma survivor!!!).  Just added a new 7,000 watt dual fuel genertor (Dec 1, 2017)
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