Need some help... off grid... may have finally killed my first set of batteries?

couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
I have two questions I'm trying to figure out and am hoping you might lend thoughts / opinions:
1)  Anything I should test or try in the current system
2)  Assuming the batteries need replacing, any recommendations?

My current setup is as follows:
4x270w panels, to Midnite Classic 200.
4x Trojan 1275 batteries (12 volt batteries, wired together such that it is equal length between all batteries so that there is not substantially more draw in the "first" battery)
12v system (with a little 110v AC to run the electronics in a propane on-demand hot water heater

For 4+ years now the system has worked great; usually max draw down to 80% (and 90% typically) as per my trimetric.

This winter I tried something different - leaving the heat on rather than draining things each time I leave.  I suspect that the on-demand water heater (which has an anti- freeze circuitry) has been kicking on at times with an electric heating element and draining the batteries down; this, coupled with the cloudiest fall / winter we've seen in a few years brought the battery bank much lower than I've ever seen.

It was 55% (and I know the Trimetric isn't perfect), so I purchased an Iota 55 am charger from this forums fine hosts, and finally installed it yesterday.  My hope was to bring the batteries back up (they had come back up as per the trimetric from that low, back to 100%, but last night were again at 65%; More worrying the voltage was around 12.2 volts (temp was 40 degrees).  I ran the generator and Iota for an hour; at first it appeared to be charging at 12.9 volts, but dropped within a few minutes to 12.6 and then 12.4.  If I understood it correctly it should have been at 13.4+ (flashing twice a second, so in "bulk" mode).  Admittedly I was testing across the full battery bank and not at the output leads of the charger.

An hour didn't seem to bring the voltage up much, BUT when I went back over to the Midnite for charging (cloudy, so not much coming in) the voltage worked up to 12.6 fairly quickly (when charging, but again, wasn't much power coming in, only a few (up to 8) amps.)


Right now I"m assuming the batteries are finally "cooked" (likely sulfated), and the charger is fine, though I know it could also be the charger (really I should try it on another, known good battery).

I'm curious what else I should check, folks thoughts on the situation, and if it appears they ARE cooked them I'm battery shopping again.  I don't recall hearing any new latest and greatest, so I'm assuming I'll be sticking with lead acid now that I have my watering habits down better, as well as the auxiliary charger.

I have a dealer that can get me Deka batteries easily, so I may look in to them as well as the T1275's again.  I may look at some of the more expensive options as well (Surrette) if it would mean simplifying the cabling I have now (2 batteries with 600ah capacity rather than 4x150?).

Sorry about the long windedness, but hopefully there is enough information there!

Oh, and lastly, yes, I DO know it would be helpful if I provided hydrometer readings, however with he batteries not fully charged my assumption is they wouldn't be much help.

Thank you for any and all thoughts and ideas!! :)

P.S.  I also installed a Whiz bang jr, and am trying to figure out how to remotely monitor the entire system (limited cell coverage in the area now, no land line (or power line) obviously.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    Your batteries may still have useful life.

    Your charging voltage set point, assuming flooded cell, should be around 14.75 volts. And held there for 2-6 hours (4-6 when deeply discharged).

    I am not quite sure what your charging profile is (bad charge controller or charging system wiring?).

    Very happy to hear your system is working well otherwise.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    From what I can tell the Midnite Classic is still working great.

    There wasn't much to wire up for the Iota charge controller; but you have me wondering if I still managed to not set it up properly.

    I'll be up there Friday and I'll check the wiring (the only item I could have reversed would be the circuit breaker on the + side, and I don't see how that could matter, but I'll double check as well as re-cleaning all the terminal connections).

    I also plan on updating my Midnite to the latest firm ware; it will be interesting to compare the Whiz Bang Jr. readings to the Trimetric.


    Thank you for your quick response Bill, and all of your great help in the past!!
  • Marc KurthMarc Kurth Solar Expert Posts: 476 ✭✭✭✭
    The dropping voltage may have been your batteries trying to draw more than 55 amps from the charger. A discharged battery will naturally try to draw a lot of current. A healthy battery does it immediately. But if the battery is way, way low on charge, the current draw can come slowly as the battery "wakes up." 

    If the charger cannot meet the demand, the voltage will be low until the batteries become more charged and reduce their demand

    BUT - if the batteries are in fact heavily sulfated, you may have a partial short(s) which is simply turning the charging energy into heat. Look for hot spots while charging.

    Marc


    I always have more questions than answers. That's the nature of life.
  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    The basic Iota has a jumper on the side of the unit. Jumper in, roughly 14.5 volts. Jumper out is float around 13.6 volts.

    Details matter (exact model number, wire awg from charger to battery back, etc.

    A sulfated battery tends to charge and discharge very quickly (looks like a smaller battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    have you tried isolating 1 battery at a time and charging it by itself first?  And the SG's would tell you if one cell is hooped... the more info you have the better...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    I'll check SG Friday and try and post up.  I used the recommended sized wire for the charger to battery connection (either 4 or 6 AWG, 4 IIRC) - 5' length (5' straight negative to negative, 3.5' charger to circuit breaker, 18" from there to + battery).  The "line" vs "load" vs "aux" terms didn't exactly match with the (60 amp) circuit breaker, but I think I got it right.  I'm not sure how that being wired backward would impact voltage anyway.

    Charger is the Iota 55 with IQ4 built in.  As noted it was flashing quickly (2 times a second), which indicates a higher voltage charge state at that point.

    https://www.solar-electric.com/ioten55amp12.html

    25' 20 amp rated heavy duty extension cord from the generator (which is a 6500w unit... overkill for this, and ridiculously noisy, but it's what I have access to until I purchase a Honda Eu2000i (likely soon!)).

    I guess for now I'll hope that since not much changed in an hour it is just a highly discharged state vs. sulfation (it didn't charge much in an hour...).

    I have another (smaller) battery I can test if I bring some terminal converters... that way at least I can identify if the charger is working correctly.
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Glad you are checking the SG. FLA batteries are very resilient, I suspect you may be okay.

    I wonder if you've do equalizing charges on your battery bank? After an even like this it's important to full charge the battery bank, then do an equalizing charge to regain any possible capacity.

    Also important to get a handle on what the load is, The continual load of the water heater's anti freeze circuitry, may well be an issue. If it's simple to drain your lines, it would be preferable. Knowing the nature/amount of this load would also be critical. Remember there is also the additional load of having to leave your inverter on and the smallest ghost loads will not let that 'sleep' if it has that type of idling.

    Also might mention that Rolls/Surrette have a different charging profile than other FLA batteries. And that there is some problem with the equalizing mode in some/most Midnite Classics.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    I most definitely need to do an equalizing charge at this point - my hope with the (generator) charger was to bring them back up, then run an equalizing charge with the Midnite (which I have programmed with the specs from Trojan for the 1275).

    Load wise I have already started just draining the hot water heater so I can leave it off.  I know it has a high load when it comes on for it's freeze protection, but I don't know how long it stays on.

    I do have a few loads on all the time, unfortunately:  the MorningStar Suresine inverter (low, but still a draw) and the fridge (SunDanzer chest fridge... uses very little, especially when the building inside temp is 40 anyway!), and lastly (and the big one) the solar thermal pumps; generally only running when it is sunny of course, and I'm using the El Cid DC pumps which don't draw a lot.  My goal has been to spend the $ up front for low-usage appliances and therefore have a smaller system overall.  Typical (total) draw at night is 1-3 amps (12v, DC).

    What I'm assuming has happened is the combination of a much cloudier than normal year (evidenced in my grid-tie solar at my primary house lower production vs. past 3 years) and the heater has allowed the batteries to be drawn down.


  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    I think you have a good handle on it (...and life buying low energy use products!)

    I'd suggest that this will likely be a corrective equalizing, checking the SG after each hour and continuing until there isn't a SG gain for 2 hours running. Rather than a maintenance EQ just checking the water level and pushing a button and walking away...

    I think you know this. Of course, if you find your SG is good after a full charge, pushing the button and walking away is fine...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    Photowhit - thanks for the reminder.  So far my spot checks of SG have been fine (though not done enough likely), and most of my maintenance has been added distilled water every few months (I check more frequently than that, but don't always need to top them off)
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    So you did not have a charger to go with your generator and batteries until recently?

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    I've never had a need:)  The first few winters weren't a problem - as posted above I'm assuming keeping the on-demand (propane) hot water heater on (with it's freeze protection) and a very cloudy winter so far are the difference.  This is a part time place mind you; though we lived there for 6 weeks this fall usually it is just 3-5 days at a time, particularly in winter when it is 1+ miles from where the road is plowed (we ski or snowmobile in).
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    This just proves every one needs a backup charger even if you don't think you need one.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    I'm not going to argue that point... though I"m happy I've not needed one until now:).  I"m heading there shortly to check a few things, hopefully charge the batteries as needed, and update the Midnite Classic for the Whiz Bang Jr

  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    I appeared to a mostly fully charged battery bank. SG from 1.245 to 1.265 depending on battery. Not much difference between cells. I'll check again after a good equalization.

    Question - with the whiz bang jr I can go to float based on end amps. With 4 t 1275s (150 at 20ah rate each) what would the recommended end amps be? I can't find the info on my 1275 tech sheet... and I'm hoping someone with a real internet connection knows:)

    If the sun doesn't come back out again I'll be trying the generator again. I'm fairly sure I found the problem and fixed it, but should test that assumption anyway before I leave Monday.

    Thank you all again for your words of wisdom, and our fine hosts for making this great resource available!
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Check the manual for your charge controller, I believe it's normally 2-3% of your battery bank capacity. So a 12 volt 600ah system would finish at 12-18 amps... Sounds high to me, but likely it's just the 12 volt system throwing me off.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    Midnite says check with the battery manufacturer;)

    I'd read 1 to 2% of battery bank, but again a reference to checking with the manufacturer
  • EstragonEstragon Registered Users Posts: 3,967 ✭✭✭✭✭
    I think it depends a bit on battery age - older take more current at float?

    Mine are set to ~1%. I'm not too worried about it though as the sun pretty reliably fails daily and ends absorb.
    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
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    edited February 2017 #20
    Midnite says check with the battery manufacturer;)

    I'd read 1 to 2% of battery bank, but again a reference to checking with the manufacturer


    Hi couch..,

    Would recommend starting with an EA of about 1.75% or 2% of 20-hour total Capacity of the bank.

    Target SG readings for a full charge is about 1.277,   and temperature compensate readings if the battery temperature is very far from the Reference Temperature of 80 degrees F,  about 27 C.

    As you know temperature compensation value is -- 5 mV/Cell/C.  Place the BTS near the center of the battery bank.

    Recommend Temp compensating the EQ voltage  --  there is a setting for this in the Classic Charge menu,  under Temp Comp.

    The Trojan batteries need relatively high charge and Float voltages.

    From what you have said of the SG readings,   the battery could use an EQ,  IMO.

    As you also know,   the EQ should not be begun until after the batteries have had a full charge,  or close to it.   A battery that has not been damaged,   can often require quite a long time to reach Veq,  if it is badly in need of an EQ.  EQing can take place over a number of days.

    And,  YES  most systems DO need a way to charge batteries from a genset (or Grid).   Lead Acid batteries have their own needs,   and often do not like to wait for the weather to cooperate in allowing charging only from Solar,   as you know.

    The Flooded batteries here have required a battery EA of just under 1% of actual rated Capacity when they were young.   Have needed to increase Vabs to achieve full charge in the past 18 months or so.   Now,  with the higher Vabs,  the required EA value is about 1.5% of C,   with a Vabs somewhat lower than the Trojans require.   These Surrettes have a lower SG for full charge,   so this,  if for no other reason will probably dictate a somewhat higher Shunt EA,  than Surrette FLAs IMO.

    FWIW,   Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    Vic, you are very right on needing a good long EQ. I do have temp correction programmed. Thank you for confirming what I've done so far with the helpful suggestion for end amps. I'd set it at 6, I'll likely raise to 10.

    I'm going to temp correct the SG readings I took the other night tonight. I'll fire up the generator tomorrow for a bit ( not sure the iota does equalize though), and hope for a sunny day.

    The system seems to be back working well now that I'm keeping the propane on demand hot water heater off and drained when I'm not around.
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    For the curious.... the charging problem was my own error. I had it in my head I'd ordered a iota 55, and purchased a 60 amp breaker.

    I'd ordered an iota 75....

    80 amp breaker and all is working correctly at the moment.

    I have the charger wired directly to the batteries (through noted breaker), but wonder if I should have wired it to the far side of my shunt; right now the shunt is of course not reading the amps I'm putting in to the battery bank.

    Lastly, a newbie question that I'm second guessing myself on and can't find the answer on line or in the midnite manual, triggered by Vic's comment above - I have the temp offset entered as -5 mv/cell/ C - is that correct (I know the "5" is I'm questioning the + vs -). I know it should be (-) above 25c and positive below in terms of offset but the midnite simple asks for offset and it can be either way....

    Thank you all again for your time and expertise - it is greatly appreciated!!!
  • EstragonEstragon Registered Users Posts: 3,967 ✭✭✭✭✭
    Only battery should normally go on the battery side of the shunt. All loads and charging sources go on the other side.

    I don't recall if the minus sign is needed entering temp comp on the classic. I can't think of a situation where you would want to reverse (increase voltage with temp) so maybe just the value.

    Are you using local app for programming? It should show you the target temp compensated absorb so you can tell pretty easily if it's going the wrong way.
    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
  • couchsachragacouchsachraga Solar Expert Posts: 78 ✭✭
    Interesting... I went in to make it "5" and the maximum value is "0"... so it looks like -5 has been correct all along.

    Right now the (generator) charger is connected to the battery as per the iota instructions. I'm going to get a longer negative lead so I can connect it to the (load and midnite charging) side of the shunt.

    Thank you:)
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