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Are You Killing Your Batteries Part 2.

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  • Mike90250
    replied
    Sorry.
    Electronics is not an easy subject to grasp. The dummies book is pretty comprehensive. And then real life never matches the textbook examples. And when you do figure out a shopping list, the local shop does not carry that model, so you have to go to the internet and hope they don't ship a brick in a box.


    You can use your existing panels, but you have to put 2 in series for about 100V, and then use an expensive charge controller like I mentioned that has a 150V input.
    Or you can change the panels to either lower voltage in the 35V Voc range, and use 2 in series with your existing controller. Or select a panel in the 80V Voc range and use your existing controllers.
    Either way, more than 2 strings in parallel, requires a OCP device in a combiner box



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  • Wiscy
    replied
    I have the wrong panels AND the wrong controller? How can that be? Surely only ONE element needs altering, not both.

    Make sure the components are compatible with each other? How? When I came here 9 months ago and 6 months ago you ran me off the comments board both times telling me to go read Solar for Dummies twice. Didn't answer my question either time. Now, I know I am asking for help, nobody HAS to provide it to me....and I appreciate any good faith attempt to set me straight. Since it was basically the same screed from you both times, I thought maybe it was a canned rant you used to shame people. Not sure why you want to do that, but hey. Whatever turns your crank. When you are Senior on a board, it is pretty easy I guess.

    I had already read Solar for Dummies once. It was the least helpful of thousands of things I read. Some help from you then would have gone a long way in me ordering the proper stuff. Instead I just had to wade into the confusion once again and do the best I could. I don't know if you are the only live body left on this forum, but I have run into you like a brick wall all the 3 times I have tried. This last time I had finally got all the parts, pieces, and wiring together and now I am trying to make what I have work. I did my best. For some reason you didn't just attack me on this 3rd attempt....so I was hoping to learn something. You did avoid the humiliation stage this time, not sure why.
    Did you just march into your solar and alternative energy projects and hit home runs everytime?

    I tried doing the research, spent 2 yrs trying to fix a place and planned it out. Spent just over $3000. Just because I am not a wizard in this realm doesn't mean I am an idiot. I fix all my own cars, computers, networking, plumbing, and everything else that ever sprang up around a modern house. This particular field of endeavor happens to be the MOST COMPLICATED thing I have ever tackled and I am proud of what I got accomplished.

    If there is an Achilles heel in my system or my knowledge....so be it. I tried hard and put in countless hours. I don't need chastising and ridicule. When I bought the panels nobody said there were all these limitations or compatibility issues. When I bought the controllers, I told them what panels I had and they told me what controller(s) would work. When I came here asking for help I was humiliated. You told me to give up and get a Pro.
    No Pro installer nearby (I quoted 3 of them) wanted anything to do with a battery system. Grid Tie only. They don't understand batteries, don't want to be on the hook for them or answer user's ongoing questions about them. They want to be done and never hear from you again. I am a complete DIY er, but I dropped my guard and was willing to hire and pay a pro. I realized this wasn't something I was going to be able to learn about completely before embarking....like many of my DIY conquests. But all I got was the runaround due to batteries and not being Grid Tied.

    So, I will go forth and make sure all my components are compatible with each other....using an abacus and a divining rod. I see people here on these forums trying to run 24v systems with 12v equipment or having a jumper cable between 2 controllers and they didn't get treated like that. If you think this site should only have Pros batting around ideas, then maybe there should be a banner saying that.

    You quoted my 24v charging requirements above, but didn't answer it. I asked some pointed questions and you didn't answer them. Just told me everything I have is wrong.
    I will be trying a different forum.
    Last edited by Wiscy; 12-19-2018, 12:27 PM.

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  • Mike90250
    replied
    Originally posted by Wiscy View Post
    Thanks for the links and info. Mike I appreciate your time and coaching.
    .......If you say my panels need 50V to 60V to charge my 24V battery bank, and my 3 panels in parallel to one controller produce 39V - How am I to reconcile that with the quote above?
    You got the wrong controllers [B]and [/B]the wrong panels. Figure out which is easier to replace. Can you return them ? Make sure the components are compatible with each other.

    With one panel 39.6v, on a hot day, you cannot expect to generate enough voltage to charge the batteries through a MPPT controller. A PWM controller would work with your panels in parallel, you would loose some system power

    39.6v - 29V = [B]10.6[/B]v x 9.35A = 99.11 watts loss [B]per panel[/B] due to voltage mismatch. You will still get 9A per panel, but the difference of panel voltage and battery charge voltage, you loose some power.


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  • Wiscy
    replied
    I still would like some opinions on how much panel/battery I have. Is my battery bank likely to be able to store most of the power I can create? Or am I way over on one or the other?

    Also, you can see my two attachments - 2 real-time screengrabs of my two controllers via the proprietary software. You can see my Solar Volts are up in the 40s which seems odd from a 39V array. Perhaps cold or cloud flare? OR the software isn't reading things right or I have something wired wrong.
    Attached Files

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  • Wiscy
    replied
    Thanks for the links and info. Mike I appreciate your time and coaching.
    I thought I DID go the 2 cheap controllers route.

    I found this on another thread Sunking said:
    For a 24 volt system the panel at max power rating needs to be 32 to 36 volts.
    Roughly 16 to 18 volts for every 12 volts of battery.

    However that rule only applies if you are using a standard PWM or shunt regulator. Using that type of regulator you will loose 30% minimum of the power from the panels.

    However with a MPPT controller those voltage rules do not apply. They still need to be at least 36 volts, but you can go as high as around 120 volts to take advantage of wiring loss efficiency at the higher voltages. At higher voltage you use less current for a given power.
    If you say my panels need 50V to 60V to charge my 24V battery bank, and my 3 panels in parallel to one controller produce 39V - How am I to reconcile that with the quote above?

    Leave a comment:


  • Mike90250
    replied
    Your solar is 2,220 watts and through a MPPT controller at 24V roughly 80A. So you will need 2 cheap 40A controllers or one expensive controller.

    There are 2 expensive, high amp controllers I can recommend :
    Midnight Classic 150
    Magnum Energy PT-100

    Use a sizing tool from the Controller Mfg to determine the optimum array configuration

    http://www.midnitesolar.com/sizingTool/index.php
    https://www.magnum-dimensions.com/re...rge-controller


    Note that at cold temps, 2 panels in series produces:
    VOC Open Circuit Voltage at -30

    Another good 60A controller that would occasionally limit your charge amps to 60A
    Morningstar MPPT-60

    Leave a comment:


  • Wiscy
    replied
    so maybe a different controller would be the simplest or cheapest change. If I go to a 36v battery I have to get a different inverter. If 50-60V are needed for a 24V bank, does a 36v batt bank require fewer or more volts than a 24V bank? And a 48v bank? I could add some batteries or reconfigure them.

    Leave a comment:


  • Mike90250
    replied
    sadly, your panels are high voltage, and cannot be wired in series, which will be very close to the kill voltage of the controllers. At 39.6V, the controller may have a hard time charging the batteries fully.

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  • Wiscy
    replied
    I believe each CC has 100V max.
    They told me I had to parallel 3 panels to each CC.
    Would have been nice if they had said something about 50-60V input needed. I tried and tried to buy the right stuff and not make such a mistake, but that simple sentence you just said....you need 50-60V to impact a 24V bank ....I never came across that info and I spent months planning.

    Electrical Specifications SILFAB SLG M 370

    Module Power (Pmax) Wp 370

    Maximum power voltage (Vpmax) V 39.6

    Maximum power current (Ipmax) A 9.35

    Open circuit voltage (Voc) V 48.2

    Short circuit current (Isc) A 9.93

    Module efficiency % 19.0

    Maximum system voltage (VDC) V 1000

    Series fuse rating
    A 15
    Power Tolerance Wp -0/+5
    Measurement conditions: STC 1000 W/m2
    Attached Files

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  • Mike90250
    replied
    Originally posted by Wiscy View Post
    Yes I think I am learning a lot we will see. I have 6 x 370W Silfab panels. 2 x EPEVER 4210 AN 40A CC's. 3 panels paralleled to each CC. CC's paralleled to the battery bank. Bank is 8 flooded lead acid golf-cart batts - 24v x 400ah.
    Battery Bank:
    4 x 6v batteries 200ah series strings (24v x 200ah) then paralleled the 2 strings for 24v x 400ah.......
    I think you don't have enough voltage for the controller to properly work.
    What is the Vmp of your panels ??
    What is the max save input voltage of your charge controllers ?
    What is the Voc of your panels ??

    Generally to charge a 24V battery, you need about 50 -60V from the panels into a MPPT controller, and will have to put 2 panels in series, if that voltage does not exceed the Max volt of the controller.

    Leave a comment:


  • Wiscy
    replied
    Thank you Mike. I will try to process what your take on the stages are. Absorb is the most mysterious, I can't tell from Sunking or your description what decreases the amps or how that is set or performed. Certainly my CC software and manual don't explain how to do that. Setting my own points and turning off the defaults on my CC will definitely put me off all the automatic things it does to keep CC and Battery safe. And I have to get it right or I will do more damage.

    The CC software and owners manual seem to use slightly different terminology and have Boost and Constant thrown into the mix. Then just when you need it to make sense, the Language Barrier pops up and their point is murky. "At this time The Same will be the same" for example. I can never tell when I am entering configuration info if it wants one battery measurement or the entire bank.

    It seems very hard to think my batteries are sulfated. They are "brand new" with 2018 born on dates. I bought them in july. I was delayed in getting them hooked up to anything because my panels and CCs and other wiring didn't come together as fast as I hoped. I bought a very cheap 24v charger in September but it did almost nothing to charge the whole bank....but my voltage readings were good and all the batteries singly tested at 6v + . The CHarger was too small, but it never read below 52% and got up to 65%. I got three panels hooked up a month ago and charging...then the last 3 panels about a week ago. I guess the waiting could have ruined them. I am clueless but they do have a 1 yr "replace for any reason" warranty.
    Last edited by Wiscy; 12-17-2018, 05:38 PM.

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  • Mike90250
    replied
    I'm not Sunking, but I'll reply to you Wiscy.
    First most of what is sold as "state of charge meters" are bogus. The ones that work, require you to install a shunt, program the size of the battery and it's efficency, and then after a couple fulll charges to calibrate it, it can come pretty close, measuring inflow and outflow.

    As to the SCO % dropping overnight, it's likely batteries are sulfated. Winter hours, you need to use a generator in the mornings a couple times a week, to bulk the batteries up, and then let the solar top them off from 10am-2pm

    Charging is in 3 stage (not phases) Bulk, where you set a voltage, and allow the battery to take as much power as it can safely inhale. Absorb, where the battery reaches the Bulk voltage, and then over the course of at least 2 hours, the amps decrease, finally FLOAT, where the last 10% of charge happens, slowly putting power in till the battery is full

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  • Wiscy
    replied
    Yes I think I am learning a lot we will see. I have 6 x 370W Silfab panels. 2 x EPEVER 4210 AN 40A CC's. 3 panels paralleled to each CC. CC's paralleled to the battery bank. Bank is 8 flooded lead acid golf-cart batts - 24v x 400ah.
    Battery Bank:
    4 x 6v batteries 200ah series strings (24v x 200ah) then paralleled the 2 strings for 24v x 400ah.

    Sunking you said most of us were undersized system. As a novice I did my best to size my system but most of that was based on what appliances I was running, not on how best to match panels with batteries. Does my system shortchange itself? I don't know what you meant by UNDERSIZE...too few panels, too few batteries?

    I barely understand what the CC's are doing with 3-phase charging (I was hoping they would be a much better battery minder than ME) but you are saying it is probably best if I override the controls and chart my own course. I just got my system installed and running just in time for shortest days of the year - December in Wisconsin. On Sunny days it seems to charge to 100% SOC in just a couple hours... then goes to float...but by the time the sun goes down (with hardly any draw on the inverter) the SOC % drops precipitously and is back to 50% or less by morning.
    Last edited by Wiscy; 12-17-2018, 03:59 PM.

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  • Mikenreurs
    replied
    Glad I came across this thread. Definitely learning a lot from here.

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  • Sunking
    replied
    Sensij Absorb phase is determined by three variables.

    1. Resistance of the battery, which you have no control, it is what it is.
    2. Charge Current which is determined by the panel wattage and battery SOC OCV
    3. Voltage you select.

    If you use a higher charge rate say from C/10 to C/5 or 10 amps to 20 amps on a 100 AH battery. you arrive at the Absorb voltage sooner, but will significantly increase the Absorb time if you charge at the higher rate. That is just the function of higher current flowing through the battery fixed resistance.

    What I am saying is you move the Set Point Voltage higher so when you reach the set point, the OCV voltage of the battery is at 100% SOC rather than 60 to 80% SOC. Just work th emath a couple of times and you will see what I am talking about.

    A fully charged 12 volt battery is saturated at 14.4 volts when both charger and battery OCV are equal which means no current. If you have say a 10 amp charger and battery resistance = .01 Ohms, Absorb starts when the battery OCV = 14.3 volts and charge current starts to taper of as the battery voltage slowing goes up to 14.4. That is a painfully slow process. If I set the voltage to 14.5 volts, now the charger will not taper until the battery OCV is 14.4 volts OCV which is fully saturated and 100% SOC in a much faster time.

    The difference is significant. Example using the 100 AH battery with a .01 Ohm resistance charged with a 10 amp charger from fully discharged. One set to 14.4 volts and one set to 14.5 volts. The battery with the charger set to 14.5 volts will be fully charged in 12 hours. The battery with the charger set to 14.4 volts will take 20 hours. Both batteries will have had the same 120 AH pumped in.
    Last edited by Sunking; 05-30-2017, 07:43 PM.

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