Battery bank not holding charge--Please help!!

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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #32
    Re: Battery bank not holding charge--Please help!!

    Most likely would just blow an internal fuse, no new pants necessary. ;)
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #33
    Re: Battery bank not holding charge--Please help!!

    My cheap does not have a fuse on the 10 amp shunt input... Just trying to keep everyone safe.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #34
    Re: Battery bank not holding charge--Please help!!

    HAHAHAHAHA!!!! No new pants were needed, although that did provide a giggle or two:)
    No rings welded to hands or acid in the eyes either! Hot diggity!

    I feel like we're getting somewhere!!!!!! :D
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #35
    Re: Battery bank not holding charge--Please help!!
    meghammock wrote: »
    Of course, it's raining/sleeting/snowing so I proooobably shouldn't do that today..
    Are the batteries out there in the sleet and snow? That could be part of the problem.
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #36
    Re: Battery bank not holding charge--Please help!!

    Indeed, they're in a rubbermaid-style tote.. Though I read somewhere that they need to be spaced about 1/2 inch apart to help keep their temperature more consistent throughout, too.. They're not at the moment.. Wonder if that'd help?..
    How much do you fancy an insulated box would help them?
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #37
    Re: Battery bank not holding charge--Please help!!

    Depending on where you live, having batteries outside would be part of the problem. They loose some of their capacity as the temperature drops (see the quote below from Windsun's battery FAQ). On the other hand, their life is extended by being cold (and the life is reduced by being hot) so you have to balance your needs. My batteries are in my garage which keeps them about 20 F degrees above ambient.

    "The standard rating for batteries is at room temperature - 25 degrees C (about 77 F). At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher."
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #38
    Re: Battery bank not holding charge--Please help!!

    Unless it is extremely cold, that isn't going to explain why they are going dead so quickly.

    There are few places in the Continental US where -20F is very common very often. The obvious locations excepted.

    Tony
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #39
    Re: Battery bank not holding charge--Please help!!

    Phew.. We definitely don't get in the negatives.. 11's been the lowest, but it's been in the 20's and 30's at night lately.. Guessing a nice little insulated home for them wouldn't help too much then..

    Trying to figure out how to post a picture on here.. I showed the wiring to someone and they said it looked pretty wonky.. I'll have time to sit and read some of the info I've printed this weekend--Hopefully I can show this to ya'll.....
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #40
    Re: Battery bank not holding charge--Please help!!

    OK--Here's a photo of the battery bank wiring.... Yea or nay?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #41
    Re: Battery bank not holding charge--Please help!!

    An insulated battery box is a double edged sword. It might keep the batteries a bit warmer in the winter, but it would also keep them warmer in the summer,, not a good thing. If you are ~ freezing at night, too cold batteries are not your issue. The cooler batteries will give marginally less performance, but not like what you are seeing.

    Tony
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #42
    Re: Battery bank not holding charge--Please help!!

    From what I can see on a 7" screen - nay.

    It looks like the pair of batteries on the left have been "ladder" on to the pair on the right. The Negative connections for the inverter & charge controller should be on one bank, the Positive connections on the other. This is the "diagonal" wiring that keeps current flowing through all batteries fairly evenly. You don't have that, so one whole set of batteries may be being left out of the system or at least not fully utilized.

    Can't judge the wire gauge from a photo, which could be another problem.
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #43
    Re: Battery bank not holding charge--Please help!!

    Good--'Cause we don't have the dough to make a box. Hehe:) What does ~ mean?
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #44
    Re: Battery bank not holding charge--Please help!!

    Well, my my my.. Isn't this getting even more interesting?!

    I believe it's #2 between batteries, #2 to inverter, switched from #2 to #8 from controller to batteries.
    BB told me how to check the voltage (safely) and they all drained pretty evenly, but, uh... Still in 2 hours :P

    I've been told not to re-route the wiring on my own.. How can I learn to do it safely? I don't think the company is willing to try to help any more.. :( Their answer was "sell us the system back".. Seems like they tried to make US feel guilty, when it's definitely looking like wiring on their part now....
    Don't know if that info helps..
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #45
    Re: Battery bank not holding charge--Please help!!

    Megan sent me some voltage readings from the batteries under load--And it sounds like they are performing OK (at least, this not the major problem right now).

    I have asked her to post what charging voltage look like now over a few hour period. Both with the genset and the solar panels (one then the other--not at the same time).

    The missing part of the equation right now is that they have no way of measuring charging/discharging currents--So we don't know for sure that the batteries are 100% OK or if there is more load/less charging than expected/needed.

    From the initial and final battery voltages, the inverter appears to be working OK, and the battery to inverter cables are functional (if not pretty). And the batteries are simply not getting fully charged...

    Around 12.5-12.6 volts resting, down to 11.2 under load and inverter alarming, resting back to 12.33 volts. All voltages where measured at the posts. This is 4x 6 volt bank of 100AH (guess) wired for 12 volts for a total of 200 AH at 12 volts.

    This after ~2 hours and somewhere between a 125 and 225 watt load on the battery bank (again, just guessing from description of loads).

    Megan, "~" means approximately equal as opposed to "=" meaning exactly "equal"

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #46
    Re: Battery bank not holding charge--Please help!!

    revisit the original post as this was said,

    "o 4 batteries at 6 volts each
    o 20 amp hour capacity"

    now seeing that to mean 2 12v 20ah batteries series strung in parallel with another 2 12v 20ah batteries series strung for a total of 40ah at 12v. that's the problem if they are only 20ah batteries as the batteries would lack the capacity to operate the inverter. please confirm the battery capacity ratings.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #47
    Re: Battery bank not holding charge--Please help!!

    Niel,

    I clarified my last post--I think it is a 200 AH at 12 volt battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #48
    Re: Battery bank not holding charge--Please help!!

    that was what the op listed and from the sound of things it could be the batteries are under rated. it's hard to diagnose from a distance. if it isn't the batteries then there is a load not accounted for or is under rated. if the inverter is all that is present for the load then charge up the batteries and leave the inverter unconnected for the same time period and see if the drain is still severe.

    edit to add- did we ever establish if it was a pwm cc and did we ever establish how many pvs are in place? (i don't want to sift through the whole thread)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #49
    Re: Battery bank not holding charge--Please help!!

    Probably a TS-60 PWM Morning Star charge controller. And appears to be 3x173 watt panels with Vmp of 24 volts (possibly Voc--don't have model number).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #50
    Re: Battery bank not holding charge--Please help!!

    i looked the pvs up before, but didn't copy the model number.
    they deliver 25.1vmp and 6.9imp

    if pwm and 77% this is 6.9ax3x.77=15.94a

    if those batteries are 200ah then it would be a 400ah bank at 12v and the charge is insufficient as 15.94a/400ah=3.99%. even if it was charging the batteries it would take a long time to reach full charge.
    if the batteries are 200ah at 6v each then i'm guessing the batteries had a high discharge to near dead leading to the following.
    pvs insufficient to bring to full charge with loads still being applied.
    long term effect of deficit in charge leads to sulfation.
    result=batteries don't hold charge and are ruined.

    again-i don't know for sure.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #51
    Re: Battery bank not holding charge--Please help!!

    As far as I know--it is 4x 6v 100AH batteries wired up to 12v @ 200 AH rated.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #52
    Re: Battery bank not holding charge--Please help!!

    ok if 100ah that would be fine and if there is only the inverter as a load and assuming the batteries, cc, and pvs are fine then that would point to the inverter doing this and again it needs disconnected to see if the capacity slide still occurs.

    100ah for 6v batteries is not a common standard as most sit in the neighborhood of about 200ah each, but i'm sure they are probably available in that capacity.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #53
    Re: Battery bank not holding charge--Please help!!

    Just so everyone is on the same page:

    I looked up the battery model; they are 215 Amp hours @ the 20 hour rate. That's 430 Amp hours @ 12 Volts.

    By the OP's diagram we deduce there are four 173 Watt panels. That's 692 total, at 77% = 532W /14.2 Volts charging = 37.5 Amps. This agrees with his installers claim of "40 Amps going into the batteries".

    Apparently the charge controller is a 60 Amp PWM Tristar, which means he's losing potential power there because his panels have higher-than-normal Vmp (apparently 25.1). Could be losing ~30% of the charge power there. Should still be enough for the batteries - but marginal.

    We now know the batteries aren't connected "diagonally" as per the Smartgauge method 2. So two of them might be largely "left out of the loop".

    I can't tell from the pic if the batteries are sealed or not. If not, we're back to "charge them up fully, let them sit, check the SG and Voltage" to make sure the batteries are still okay.

    I'd recommend moving one of the inverter/controller connections (either + or -) to the other set of batteries. Also checking the wire gauge. 8 AWG should handle the charging all right, and 2 AWG should work for the batteries & inverter. I'd be suspicious of those cables being 4 AWG, though.

    And where are the fuses? Tell us there are fuses somewhere.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #54
    Re: Battery bank not holding charge--Please help!!

    if the tristar is a pwm then there's no way to get 40a from 4 of those pvs as 4x6.9a=27.6a. derated for inefficiencies at 77% is 21.25a. 21.25a is 4.94% and is still a viable rate to charge the system given time. if 40a was seen then it has to be an mppt controller.

    if all this is so and all the batteries and cc are ok then it still points to the load source as possibly drawing too much or there is a possible partial short someplace.

    we're shooting in the dark with hypotheses, but we're trying.
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #55
    Re: Battery bank not holding charge--Please help!!

    I believe the AH capacity is actually 215.. The guy from the company said it's 430 AH total, and the battery label said AH 20, then had the number "215" under it. Trying to look it up online to decipher what number means what! Can't seem to find the daggone thing though...
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #56
    Re: Battery bank not holding charge--Please help!!

    good enough for me as i'll take them to be 215ah each then. in any case if you have 4 of those 173w pvs that the controller regardless if pwm or mppt would fall in line to be able to charge the batteries.
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  • SteveK
    SteveK Solar Expert Posts: 387 ✭✭
    #57
    Re: Battery bank not holding charge--Please help!!

    Why aren't we doing the easy thing again?

    Something like disconnect the inverter wires and the controller wires from the battery bank, then charge the batteries and let rest overnight? Take voltage and or SG readings and report back here?

    I don't see how an undersized charge circuit is going to lead to discharging fully charged batteries in 2 hours.......

    We need to know if the batteries are toast or tea.
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #58
    Re: Battery bank not holding charge--Please help!!

    Ya'll are so far ahead of me.. Haha!

    Cariboocoot is correct with the batteries & panels :) (sorry.. I must suck at surfing the 'net to find battery info!)

    "I'd recommend moving one of the inverter/controller connections (either + or -) to the other set of batteries. Also checking the wire gauge. 8 AWG should handle the charging all right, and 2 AWG should work for the batteries & inverter. I'd be suspicious of those cables being 4 AWG, though."
    --is this something I can safely do on my own? With no acid baths? I don't know when the next time the company could come out would be.. And which cables are you suspecting of being 4 AWG? I think I remember them saying everything but the cc to bb cable being 2 AWG.. Cc to bb was said to be 8 (switched from 2 AWG to 8 AWG in an attempt to make things work...)
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #59
    Re: Battery bank not holding charge--Please help!!

    optimal wire or optimal wire placements are not going to drain your system like this and can be addressed after the source of the real problem is found.

    i suggest pulling one of the inverter cables off of the battery bank and leaving it off being careful of course not to short things out and then proceed to get a full charge into the batteries from the pvs. this could rule out the inverter if they still lose capacity.

    now if you don't feel at ease doing this then i would approach the people you got the system from and tell them to take their stuff back and either give you all new or a refund as it is not working somehow.
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  • meghammock
    meghammock Solar Expert Posts: 43 ✭
    #60
    Re: Battery bank not holding charge--Please help!!

    Never done it before, but provided I'm not a clumsy goof, taking the inverter cables off should be easy enough, yes? :) I will do that tonight and let the batteries charge tomorrow.. Should be pretty sunny!

    How could taking the cables off cause a short? (I ask so I can be careful not to let that happen)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #61
    Re: Battery bank not holding charge--Please help!!

    The problem is you will be using metal wrenches to loosen the hardware...

    The "proper" safety protocol is to wrap the wrench(es) with electrical tape except for the end on the bolt. That way if you do touch other metal--you will not get a short circuit.

    You will not get a shock on a 12 volt battery bank (unless possibly your hands are covered with salty water)...

    It is not hard, but you cannot turn of batteries. If you are a klutz with tools or don't have any experiences with wrenches--Learning on a 430 AH 12 volt battery bank is probably not the best place too learn.

    If you have used wrenches before and feel comfortable with them--It is not difficult to do. Just make sure the wire end does not touch elsewhere.

    Placing plastic/plywood on the bank where you are working to protect battery terminals from accidental contact can help too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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