Just got my system up and running

somepriestssomepriests Registered Users Posts: 7
Hello folks,

I just got my system up and running, but now I need some advice as to how to tighten up the charging of the batteries. First, here is the system:

1. 2 Hyundai 260 panels (260 Watt making 520 Watts total)
2. MC4 connections
3. 4 Walmart group 29 Marine batteries/126 AH for 504 AH total
4. FlexxMax 80 Charge controller
5. Cen-Tech 2000/4000W Inverter
6. 63 Amp DC breaker from the Batteries/Inverter
7. 15 Amp DC breakers between the PV arrays/Charge Controller and the Charge Controller/Batteries

I am trying to determine how to get the most out of these batteries. First off, I know that the Walmart batteries are not completely Deep Cycle, but a lot of users have have great success if they take care of them. So:

1. What do I set the Charge Controller to for its Bulk charge? 13.8V, 14.4V, I just don't know since I don't have that much experience with these batteries. I don't want them to overheat or become damaged.
2. What do these batteries "top-out" at. Should I be seeing something like 13.8, or much lower? I read that 12.2V is 50%, and that I should not take them below that without damaging them, not true?
3. Should I be "boiling" these lead-acid batteries during equalization every month at 15 Volts? I have heard two different things.

In any case, I will start there with these questions, and I am sure I will have more.

Thanks in advance

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just got my system up and running

    Welcome to the forum.

    You've got a few problems.

    Let's start with the fact that much panel can put out over 30 Amps of charge current on a 12 Volt system. This means your 15 Amp breaker between the controller and batteries is going to trip all the time.

    The four batteries in parallel are going to have a good potential for current sharing problems unless they are wired just right. Take a look at these diagrams at Smart Gauge: http://www.smartgauge.co.uk/batt_con.html

    Now about that 2kW inverter. If you were to actually run it at its peak continuous output it would pull roughly 167 Amps +/-. Your 63 Amp breaker on the inverter will limit power output to about 750 Watts.

    As for the battery charge set points, well the batteries are going to die sooner rather than later. Know this. As such, the Absorb Voltage should be at least 14.4. If it doesn't reach proper Specific Gravity increase the Voltage. Possibly 14.6, but not likely 14.8. You will have to experiment a bit to get the proper SG with minimal water loss. Equalize (higher Voltage charging) only if necessary due to uneven SG between cells. Float at 13.8 is fine, as that is a standard for automotive applications.
  • somepriestssomepriests Registered Users Posts: 7
    Re: Just got my system up and running

    Thank you! Everything you stated happened. The 15 Amp breaker worked for a while but tripped during the Absorption phase. The Inverter tripped the 63 Amp Breaker after it buzzed for about 5 seconds. The freezer it was hooked up to never started up. I most likely will go with the 63s on the PVs and batteries, and pick up a higher breaker for the Inverter.

    As for charge current, the FlexMax defaulted to 14.4 and 13.8, so it is apparently trying to teach me the correct way to do this as well. I will have to reset it.

    Second set of questions:

    1. The Group 29 Marine batteries are Lead Acid, so I don't figure I can check the SG. Can I still use 14.4 and 13.8 for my limits? 15 for Equalization?
    2. The batteries will die sooner than later if I keep it wired the way it is, or is it the battery quality that you are addressing here?
    3. Sounds like Equalization is not a rule. How often shall I do it, if at all?
    4. PV arrays are in Series, for a 24 volt system. The Charge Controller is stepping down the voltage to the batteries at 12V. I guess I need to ask, what breakers go where. PV to the Charge controller, Charge Controller to the Batteries, etc.

    Thanks
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Just got my system up and running
    The four batteries in parallel are going to have a good potential for current sharing problems unless they are wired just right.
    Welcome to the forum,
    I would put it this way: The four batteries in parallel are going to have current sharing problems even if they are wired just right.
    read this to learn why: http://forum.solar-electric.com/showthread.php?14674

    As to your questions about charging and maintenance, everything depends on whether you can check the specific gravity (SG). If you have unsealed batteries, you can adjust your charging parameters to hold the voltage as low as possible while achieving your SG goals. If you measure SG and get yourself a DC current clamp meter, you might get a few years from those batteries.

    If those are sealed batteries, the best you can do is follow the manufacturer's charging recommendations, but that is often impossible because the manufacturer's recommendations are likely to be for a charging protocol that your equipment cannot deliver. Grid connected battery chargers use different charging protocols than solar battery chargers. Use your remaining time with these batteries to learn about real deep cycle batteries in anticipation of buying your next set of batteries.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Just got my system up and running
    Sounds like Equalization is not a rule. How often shall I do it, if at all?

    if your batteries are sealed, equalization is probably not a good idea... you might overheat the catalyst in the battery and you can't replace the water that is consumed. If they are not sealed, checking SG will tell you when to equalize. When you do equalize, you might want to do it one string at a time. Equalization is hard on batteries and you only want to do it to the one battery that needs it.
    PV arrays are in Series, for a 24 volt system. The Charge Controller is stepping down the voltage to the batteries at 12V. I guess I need to ask, what breakers go where. PV to the Charge controller, Charge Controller to the Batteries, etc.

    You need a circuit breaker between the battery and anything and everything that is connected to the battery.

    Additionally, you should have a combiner box near the panels that has a breaker for each panel. Technically, you don't need this with only two panels, but it is smarter and safer to have the combiner box. The combiner box is a good place to put a lightning arrester, and the circuit breakers are also switches that allow you to disconnect the panels and de-energize the cable to the solar charge controller. The only way to safely work on that cable is to de-energize it by flipping the breakers, or to throw a heavy blanket over the panels. The breakers also are a convenient way to check on your panels... you can easily turn on one panel at a time and confirm that they are all performing equally.

    btw, it's good that you are asking questions here... Your system is large enough to electrocute someone, burn down your house (or RV or boat or whatever), or serve as a path for lightning to enter your structure.

    Tell us more about how and where this system will be used...

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Just got my system up and running

    Since you never mentioned how you have your Batteries cabled, you should have at least 2/0 and 4/0 would be better. The amp draw capability of that Inverter requires at least a 200-250 amp fuse / breaker from the inverter to the batteries. Your battery interconnects should be 2/0.

    You might get away with less if you keep the amp draw down. You mentioned a Refrigerator, it could easy draw 800 w ac starting or defrosting.

    If you don't do it right in the beginning, you'll just keep throwing more money at it over and over, because it will fail. It's hard for people to build a system on here a paragraph at a time.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just got my system up and running
    Second set of questions:

    1. The Group 29 Marine batteries are Lead Acid, so I don't figure I can check the SG. Can I still use 14.4 and 13.8 for my limits? 15 for Equalization?

    I believe you mean they are sealed. Most batteries are lead-acid, whether sealed, capped, AGM, or even gel. If you can't open the caps and see the electrolyte inside you can't check SG nor should you equalize (unless the manufacturer says otherwise).
    2. The batteries will die sooner than later if I keep it wired the way it is, or is it the battery quality that you are addressing here?

    A bit of both. The RV/Marine type batteries don't stand up well to repeated deep cycle, despite the name. And without being able to get just the right charging regime they won't last as long as they could.
    3. Sounds like Equalization is not a rule. How often shall I do it, if at all?

    As above: if you can't check the SG you really can't do an EQ cycle because you won't know if one is needed and can't tell if it's had any benefit if you do.
    4. PV arrays are in Series, for a 24 volt system. The Charge Controller is stepping down the voltage to the batteries at 12V. I guess I need to ask, what breakers go where. PV to the Charge controller, Charge Controller to the Batteries, etc.

    You have only two panels and they are in series. As such the panels themselves do not require any over-current protection. Putting a breaker on the output would serve only as a disconnect. I think you'll find those panel spec are something like Vmp 30 Imp 8 and would normally call for a 15 Amp "series fuse" (breaker). The output from the two will be around 60 Volts @ 8 Amps peak.

    From the controller to the batteries is another matter. The FM80 will down-convert the higher Voltage to greater current so the output could be 34 Amps. The breaker/fuse on the wire (and the wire itself) from the controller to batteries must be able to handle more current than that. Typically you put in the largest wire the controller will handle physically and circuit protection accordingly to allow for expansion in future (better to wire it once than twice). The danger here comes not from the panel output, which is self-limiting, but from the batteries' ability to dump hundreds of Amps through the circuit should a fault develop in the controller. As such you limit the current in the circuit to the maximum the controller was designed to handle, or the maximum you expect to use. The manual with the FM80 has recommendations for this, but you'd be looking at 6 AWG and a 100 Amp breaker/fuse at most.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Just got my system up and running
    You have only two panels and they are in series.

    I'm not so sure they are in series. The OP wrote: "PV arrays are in Series, for a 24 volt system." I'm guessing that he has two "24 volt" panels in parallel, down converted to a 12 volt battery bank.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just got my system up and running
    vtmaps wrote: »
    I'm not so sure they are in series. The OP wrote: "PV arrays are in Series, for a 24 volt system." I'm guessing that he has two "24 volt" panels in parallel, down converted to a 12 volt battery bank.

    --vtMaps

    Either way they would not require circuit protection.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Just got my system up and running

    yup, specs are:

    255 260 265
    Nominal output (Pmpp) W 255 260 265
    Voltage at Pmax (Vmpp) V 30.8 31.0 31.2
    Current at Pmax (Impp) A 8.3 8.4 8.4
    Open circuit voltage (Voc) V 37.7 37.8 37.9
    Short circuit current (Isc) A 8.8 8.9 9.0
    Output tolerance % +3/-0
    No. of cells & connections pcs 60 in series
    Cell type - 6” Mono-crystalline silicon (Hyundai cell, Made in Korea)
    Module efficiency % 15.8 16.1 16.4
    Temperature coefficient of Pmpp %/K -0.45 -0.45 -0.45
    Temperature coefficient of Voc %/K -0.33 -0.33 -0.33
    Temperature coefficient of Isc %/K 0.032 0.032 0.032
     
    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
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just got my system up and running

    One of the reasons I do not like Blue Sky controllers.

    I think this is one of the ones where if the input Voltage to output Voltage is a high ratio it limits the maximum output current.

    So if these panels actually are in series @ 60-ish Vmp on a 12 Volt system you're losing a lot of power potential through this controller.
  • somepriestssomepriests Registered Users Posts: 7
    Re: Just got my system up and running

    Great advice!

    I am running 4 AWG wiring from the charge controller to the batteries, broken by a 63 Amp, then connected in parallel by 4 AWG wiring per the guidance you guys provided below. I then plan on constructing the 4 or 2 AWG link via a 200 to 250 AMP breaker to the inverter. I can experiement with these batteries and see how long I can get them working, or perhaps I will be in the market to return the batteries and just pick up some actual Deep Cycle and do it right. My inverter is limited to a 12 Volt Capacitance, so that is why they are in parallel. It works well at this point, but I am sure that I am losing efficiency.

    In answer to the question below, I am running a refrigerator on the system in my home, so far...
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Just got my system up and running

    #4 from the controller to the batteries is ok, but for the battery connections they recommended 4/0 and 2/0 wire, not #2 and #4. There is a BIG difference in the size (and cost).
    If you use #2 and #4 it will not handle the amount of current you could draw with that inverter. You need to use 2/0 (00) and 4/0 (0000) wire.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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