Winter Battery Woes.....

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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #32
    Re: Winter Battery Woes.....

    Kamala, you rock. And I still liked your original avatar better. :D

    If that's correct, then the strings are certainly not properly balanced (equally paralleled).

    I see that Green X and Yellow X are both at the negative end of their respective strings, but Blue X isn't. Not sure if that means anything though...
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #33
    Re: Winter Battery Woes.....
    dwh wrote: »
    ... I still liked your original avatar better. :D ...

    Well... I suppose since winter is coming on.... and the camper is going inside :cry::grr ...

    I can revert. :cool:
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #34
    Re: Winter Battery Woes.....

    that seems to be how i interpret the original drawing as well. what is being done is that the strings are being piggy backed so that the farthest strings needs to pass its current through the next strings wires resulting in more current passing in some wires than others and the result is it is not balanced.
    to make it right, assuming each string has identical wire lengths, i would make both a common + and a common - for each string to tie to and tap the inverter and controller leads to those common points.
    you could also gain some balance by another means, but i won't go into it as it would not yield as good of a result.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #35
    Re: Winter Battery Woes.....

    OK, I see the original sketch has 2 wires on top of each other.....

    In other words, a fine example of how to do the wires wrong :(

    Makes sense, the first battery to go bad, pulls the first string down, and then the weakest battery in the other strings goes bad too.

    With the short charge times, and short run time, I'll bet capacity is way reduced, and all the batteries are pretty sulfated. That matches with the low charge voltage. Bummer.
    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
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #36
    Re: Winter Battery Woes.....
    Kamala wrote: »
    Well... I suppose since winter is coming on.... and the camper is going inside :cry::grr ...

    I can revert. :cool:

    Solar Aborigine! Bwuahaha!
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #37
    Re: Winter Battery Woes.....

    I might do the battery bank this way. I've left off the parallel connections. I would use the buss bar method.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #38
    Re: Winter Battery Woes.....

    Yea. Split the strings from each other and use equal length wires to parallel each string to a common point to balance everything out.

    Also make sure that the wiring of each string is the same.


    That still doesn't address the difference in ages/capacities of the batteries though. A couple are bad now, a couple were already replaced...that's a lot of mixing and matching.
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #39
    Re: Winter Battery Woes.....

    To Busby,

    The temp sense is there not so much to prevent catastrophic failure as it is to deliver correct charge. A cold battery needs a higher charge voltage, a warm one less of same.

    Good luck!
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #40
    Re: Winter Battery Woes.....

    To the OP,

    I have been away, and confess that I haven't read the entire thread, but here is my quick take. Too many batteries, too much loading, and not enough PV.

    While it seems like in the summer and fall you are getting fully charged, my guess with your loading each day you go into a bit a of a deficit charge, and have since the beginning. The result has been I think you have prematurely killed you batteries.

    From your original post you said that you had ~660 watts of panels, and you were using ~ 2.5 KWH day. My rule of thumb is on an ongoing, day in day out basis, if you take the STC rating , divide that number in half to account for all system loses, then multiply that number by 4 to represent the average number of hours of sun you car expect, day in and day out. So in your case, 660/2=330*4=1320 wh/day. So it would seem like you have been routinely drawing about twice as much power per day as you are producing.

    Add to that, you Pv will only put out a max of ~10amps. when you really need a minimum of ~15 amps, and ideally closer to 30 (48vdc).

    Sorry to duplicate anyone else's efforts, but I am traveling and only have a short time to be on line.

    T
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  • Busby573
    Busby573 Registered Users Posts: 11 ✭
    #41
    Re: Winter Battery Woes.....

    Kamala, your interpretation is right on, that's exactly how they are wired. So basically what you are saying is that the way they are wired they are not being charged/discharged equally which is causing some to fail and others to be fine.

    I also agree that at this point 3 banks of batteries is unnecessary. When we get our house refinanced we're getting 3 more similar watt panels so the system will be upgraded to around 1.3 KW, but during the winter we get so little sun anyways I don't think it's going to honestly matter that much. The difference is going to be .7KW instead of .35 KW solar per day, which doesn't solve the problem. I'm going to take the ones that are operating properly and use 2 strings, since 3 just isn't necessary.

    Kamala, according to your diagram of the way you think they should be wired, how and where would they be connected to the Inv/Ch based on a 48V system? The drawing explains how they should be wired in each individual string, but I'm just not sure how you get them to the Inv/Ch. Would you run a wire from each individual string and connect them all to the Posi/Nega coming from the Inv/Ch?

    Thanks for the help guys, it's hard to get the right info on specific cases just from reading FAQ's. One last question though. Is there a way to "repair" the sulfated batteries? Honestly I think if I can get 2 strings of the batteries I have ATM working properly and efficiently I'll just get some bigger AH rated batteries when these die of natural causes, but I'm just curious since these suckers are expensive.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #42
    Re: Winter Battery Woes.....

    The general answer is there is no way to repair sulfated batteries.

    However, some people/battery mfg. recommend lots of equalization and discharge/charge cycling (equalize at 15-15.5 volts at ~5% of battery capacity for multiple hours).

    If you choose to try and "overcharge" your batteries--watch their temperature and electrolyte levels (plates need to be covered before charging, too full and the electrolyte may expand from heat/gas content and flow out onto the top of the batteries).

    Note that over equalizing can be dangerous... Overheated batteries, lots of hydrogen gas production, and acid overflow/spray. Only perform in a well ventilated area, avoid sparks, wear safety equipment, do not leave unattended.

    Also, there are "desulfators" that, some folks believe, will repair sulfation (or at least delay its onset).

    Solar Converters Battery Desulfator

    The results of such "desulfating" is probably "mixed" at best (with low chances of any improvement)...

    And there are known issues with desulfators with some MPPT type solar charge controllers (the electrical "noise" from desulfators cause charge controller to reduce its output by quite a bit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Busby573
    Busby573 Registered Users Posts: 11 ✭
    #43
    Re: Winter Battery Woes.....

    Got it, sounds like de-sulfating is somewhat risky with non-optimal results. I've heard of a guy in Spokane, WA who has a setup that can de-sulfate batteries, but it sounds like it's not really worth it.

    Just waiting on Kamala's reply on the right system wiring, and then I think I will reduce the system to 2 Banks and rewire them.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #44
    Re: Winter Battery Woes.....

    Busby573,

    Just to re-iterate... I have no idea if your batteries can or cannot be restored by various charging/chemical/electrical devices or not...

    This is just my personal opinion that your chances for results are not high--And I would not spend much (of my) money on trying to restore the battery's condition.

    In any case--proper monitoring (and operation) of your batteries while in service (and in storage) will do a lot to extend their service life.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #45
    Re: Winter Battery Woes.....
    Busby573 wrote: »
    Just waiting on Kamala's reply on the right system wiring,

    The proper way would be to run equal length +/- wires from each string to a common point, then from there to the inverter.

    EDIT: You also connect your solar charge controller at that common point.

    Busbars are the best way, just have to find the right size/capacity:

    http://www.midnitesolar.com/productPhoto.php?product_ID=207&productCatName=Busbars&productCat_ID=17

    Also note that each string should have a "BigAss"(tm) fuse in the positive line.
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #46
    Re: Winter Battery Woes.....

    The drawing now includes the bus bars. The yellow batteries have been moved to show the cables with equal length. The two open terminals on each bus bar are for the charge controller and inverter connections.

    K
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  • Busby573
    Busby573 Registered Users Posts: 11 ✭
    #47
    Re: Winter Battery Woes.....

    Thanks man! Just gotta buy two busbars and hook it all up, then hopefully no more winter battery woes!
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #48
    Re: Winter Battery Woes.....

    Which reminds me, I meant to post this link I found the other day...

    http://www.electrical-insulators-and-copper-ground-bars.com/index.html


    (Winner of the "Helluva Domain Name" Award.)
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #49
    Re: Winter Battery Woes.....

    Don't forget the fuses. I left them out of the diagram.
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