How to best wire multiple charge controllers to batteries

ChristineChristine Posts: 14Registered Users ✭✭
Last year I got 16 Sams Club 6 volt golf cart batteries, am off grid and don't have nearly enough panels.   Recently had a visitor who knows a lot about solar install a few more panels, increasing my solar by about 70%, but I didn't see the extra panels making much difference.  

My C40 was at capacity, so we used a cheapo 30 amp Morningstar controller I had around for the new panels.  My friend told me that I should attach all the wires to one neg and one pos at the batteries, but the battery studs aren't big enough.   He left yesterday and I came home last night and couldn't even run my water pump without unplugging the house.   I also had noticed that my batteries never got full, the generator ran forever and the inverter and the Morningstar controller showed totally different voltages, Morningstar full (green light) and C40 only one blink.

My friend also had hooked up to the batteries a pretty cool looking meter thing to monitor the system .   So I go out to check this morning because my power was totally off when I got up (inverter must have shut off) and thought I'd start by taking that gadget off and almost burned my fingers, it was so hot!  The insulation had melted off one of the wires.  And I removed the wires for the new solar panels because both were red, really old and had black tape on the end, very confusing. 

On a different system, a few months ago I had tried to add a second panel to a camper system with a separate charge controller and it never worked (no power would go in) until I wired the new panel to the existing panel, using only one charge controller.

Where can I find some info on how to best attach inverter and multiple charge controllers to the batteries?

Is it possible to extend the golf cart battery studs so you can attach more cables?

Been off grid with very small wind and solar system since 2007, but as I'm expanding my system I'm lost, appreciate some pointers!

Christine





Comments

  • ScoobyMikeScoobyMike Posts: 27Registered Users ✭✭
    Hello Christine,

    Something in the new system is not wired correctly, you should probably back up to your previous setup if you can.  If it was me I would probably bring in the battery charger first and make sure it is charging the batteries (use a volt meter with charger off, then on).  Then connect the inverter & test it, and finally bring in your original charge controller.

    To answer your specific question, most people use terminal blocks to wire up all of the different components.  You would have 1 terminal block for battery +, and 1 terminal block for battery -.  Terminal blocks come in various sizes, anything from 2 posts to 20 posts.  Make sure you get terminal blocks large enough for your wire gauge & connectors. You would use 1 large gauge wire from each terminal block to the battery +/-, then separate wires from the terminal blocks to your charge controller, battery charger, inverter, etc.

    The new meter should be connected through a shunt resister on the - side of the battery. Google shunt resister and you will see pictures of various shunts.  Is there a shunt?

    How are your 16 batteries connected together?  Can you take a picture?

    1.2KW off grid system; 2 strings of 2ea 305W 60 cell panels on a redneck ground mount;  MNPV3 combiner feeds a MN Classic 150 located 100' away;  12V 460AH FLA battery bank powers a cabin-wide 12V DC system as well as a Cotek 700W PSW inverter; Honda EU2000i  and IOTA 55A charger bridge cloudy days and a Champion 3800W generator for short duration, power hungry appliances.

  • BB.BB. Posts: 27,578Super Moderators admin
    It sounds like he put on a DC Watthour\amphour meter of some sort. They are frequently rated to 100 amps or more, but in reality, much more than 15 amps is the maximum continuous current I would use.

    http://www.rc-electronics-usa.com/ammeters/r102-amp-hour-specs.html

    People do not realise how tough an environment off grid solar is for wiring and stuff. Heating is P=I^2*R .... 2x more current is 4x more heating. AC inverters and charging\discharging batteries can be near maximum current for many hours.

    Even using NEC ratings, I highly recommend derailing the code by 0.80 (or 1/1.25) for solar. Example 15 amp rated 14 awg would be 15a*0.80=12a maximum continuous current).

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChristineChristine Posts: 14Registered Users ✭✭
    Thanks!  Here are a couple pictures.

    Yes, a shunt, it was HOT and melted the wire:



    And here are the batteries:



    So I took the gadget off and the wires to the new panels (OLD wires) and now everything is working fine -- but don't know yet whether it was the gadget or the 2nd solar charge controller causing the problem.

    I wish I had taken NOTES, but I think since we first put on the second controller we've had problems.  I've been incredibly busy, not home a lot and was glad to have someone to help with this, but now I regret not paying attention.

    Am back to where I was a month ago, after huge amounts of gasoline for the generator and that reminds me, recently someone said the generator had current running on it too!   I checked it today and all was good, have no idea how that could happen.  
  • PhotowhitPhotowhit Posts: 4,606Solar Expert ✭✭✭✭
    8 strings of batteries at 12 volts will be difficult at any time. How old are your batteries?

    It sounds like you are committed to off grid, I'm guessing you don't have the grid available and got started with a 12 volt system and kept adding on? The problem is that it is nearly impossible to maintain even resistance through all the batteries.

    I'm going to make an ugly suggestion, and suggest figuring out your daily load and make the jump to a 24 or better a 48 volt system. This will likely mean scarping your Morningstar charge controller, but your C40 will handle up to 40 amps at 48 volts or about a 2000 watt array. If you have panels in compatible sets of 4 you could use the same array/panels. You may want/need to find some compatible panels to even out the array.If your batteries are still good they can be reconfigured into 2 string of 8 for a 48 volt battery bank. This would mean you would need to replace your inverter! Not sure what size/type you have.

    What type and voltage of panels do you have? Type and wattage inverter? Age of Batteries?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • PhotowhitPhotowhit Posts: 4,606Solar Expert ✭✭✭✭
    Things you know... You have a huge battery bank of roughly 20Kwhs, You have 1680 amp hour 12 volt battery bank and the max you could be charging it with is 70 amps if both charge controllers are maxed out. That's about 4%, before the possibility of the additional 30 amps, You had a max potential (not knowing your array) of 2.4%. We and battery manufacturers, typically recommend 10-13% charging for systems in daily use.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • PhotowhitPhotowhit Posts: 4,606Solar Expert ✭✭✭✭
    Okay, back you your question. How to best wire multiple charge controllers. most people with a system your size will have a breaker box. Single leads from the battery will come into the breaker box and the charge controller can be connected to a bus bar, either from the charge controller or from a breaker. Midnite solar makes DC Power Center boxes as well as E-Panels. The E panels handle Ac and DC breakers. They typically come with bus bars for + and - and a large breaker for your inverter.

    Image result for Mini DC Disconnect Power Center

    Here is my E-Panel wired pretty much as a DC power Center. The 2 things on the right are charge controllers. On the left is an inverter. Solar comes in from the back at the top center and + goes to breakers on the top left, then out to the charge controllers, back from the CC to the breakers on top right, then to the bus bar connected to the main breaker and the large single set of cables going to the battery. The solar negative goes to the bus bar next to the shunt where the other large battery cable is on the other side.




    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • BB.BB. Posts: 27,578Super Moderators admin
    It looks like a ground wire from the shunt (negative side of battery bank) to the meter\whatever device that was.

    When you have heavy and light ground wires in a system, you have to be very careful. You can have parallel current paths for ground, and if the small ground wire went elsewhere in the system (say a second ground from that controller}, you could have lots of current going through that small wire. Causing it to fry.

    Or, for example, if one of your heavy ground connections went open\high resistance, them the current would flow through the too small wire.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChristineChristine Posts: 14Registered Users ✭✭
    Thanks all, let's start with answering some questions.  

    When I started to build in 2006 I wanted to pay the power company to run the wires UNDERGROUND to not ruin my beautiful 270 degree NO POWER LINES view.  They said they couldn't run underground due to their system and I told them to take a hike.  Since then they've brought in power all over, but I still have some unobstructed view.  They actually put a pole right next to my property to entice me to hook up, I cried.  Then I bought the neighbor lot and thought I'd put power there, since it had the pole, but at the end of our onsite meeting they told me the building dept. would come to inspect their box -- no way.  I've been building with adobe and had several "illegal" storage buildings.

    I first started in 2007 with four 6v Interstate batteries, a 403 wind gen, one Unisolar 64 watt panel, the C40 and a battery charger.   I used to camp off grid a lot, was used to little consumption.  Just a few weeks ago my big side by side fridge started to run full time.  Had it on an appliance timer 3 times a day for half an hour and used the freezer as fridge and used the fridge side to store coffee, spices etc.  When I first got the fridge over 10 years ago I thought I could just turn it off at night, didn't realize that the auto defrost would never run and ended up with a thick sheet of ice in the back of the freezer and it wouldn't work anymore. You should have seen the repair guy!

    I just bought the batteries last August, don't know why they look so crappy.   My old batteries were shot and I about doubled my capacity.

    The inverter is a cheapo Chinese 3000 watts, barely enough to start my water pump and incredibly, it's still working after 9 or so years.

    And yes, I've considered going to 24 V, but then I need a new battery charger, inverter and the C40 is not enough for all the panels I now got.  And they're all different, I got some 64 watt Unisolar panels, a couple Kyocera 135 watt and some old gifted panels (all on the C40) and recently 3 cheapo 150 watt panels.  The wind gen is wired to my emergency backup system with old batteries.

    I'm sure eventually I'll go to 24 volt, whenever I paid down my debt.  My goal is to not have to run the generator all night anymore (I stay up late) and I'm thrilled to see 5 blinks on the C40 after only 1.5 hours (mostly cloudy today). 

    My friend and helper has been advocating for an MPPT controller and showed me a web page claiming that I'd immediately increase my power by 30%.   I'm not sure that the 30% is an average, maybe a max during certain daytime conditions when you produce and use power?   

    That breaker box looks nice and hopefully eventually I'll get there.   But I'm still wondering why I have these problems with the second solar charge controller.   Couldn't get it working on my camper with only two of these golf cart batteries and it's not working either on my main system.  Unless it was just that meter causing the issues, need more time at home to do more testing.
  • ChristineChristine Posts: 14Registered Users ✭✭
    And I just looked at terminal blocks at https://www.solar-electric.com/catalogsearch/result/?q=terminal+blocks

    What do I need?

  • ChristineChristine Posts: 14Registered Users ✭✭
    That's unless I get a breaker box.  My head is spinning.  But I'm happy because the batteries were actually FULL this eve and the generator is off.
  • PhotowhitPhotowhit Posts: 4,606Solar Expert ✭✭✭✭
    Christine said:
    My friend and helper has been advocating for an MPPT controller and showed me a web page claiming that I'd immediately increase my power by 30%.   I'm not sure that the 30% is an average, maybe a max during certain daytime conditions when you produce and use power?    
    With panels designed for the battery voltage of your system, there may be a 10% advantage with MPPT type charge controllers. We've actually had a major designer say that here.
    Christine said:
    and recently 3 cheapo 150 watt panels.  
    Are these the panels on the Morningstar controller? Are they 60 cell panels or 36 cell panels? Do they produce 17-19 volts or 26-31 volts VMP? The voltage may be too high  for the Morningstar controller.150 watt are usually in the 17-19 volt range, but worth checking, particularly if they are older panels (since they were gifted to you it's worth checking)
    Christine said:
    I just bought the batteries last August, don't know why they look so crappy.   My old batteries were shot and I about doubled my capacity.
    Usually you don't want to double your storage capacity without doubling your charging capacity, don't want your system to be out of balance. Looks like you will need frequent charging from your generator. Many/Most battery banks die from chronic under charging!

    I would have rather you be 'over paneled' than have too little charging capacity. As I've note 8 strings of batteries will create problem particularly as they age. This site talks about the reasoning and maintaining equal resistance through each string;

    http://www.smartgauge.co.uk/batt_con.html

    Christine said:
    The inverter is a cheapo Chinese 3000 watts, barely enough to start my water pump and incredibly, it's still working after 9 or so years.
    Cheap inverters can be expensive! LOL. They tend to be inefficient and if it is a Modified sine wave inverter, it will actually use more energy with things that have motors and shorten their lives due to the extra heat. Might be worth checking what the inverter uses while idling and it's efficiency in converting DC to AC.

    Christine said:
    My goal is to not have to run the generator all night anymore (I stay up late) and I'm thrilled to see 5 blinks on the C40 after only 1.5 hours (mostly cloudy today).  
    I don't know what your additional loads are, or where you are located in terms of how much sun you get, I suspect between the dust on the batteries, building with adobe and wide vistas, you live in an area with a good bit of sun. I suspect you have enough array to run a fridge as the major load without running a generator. I also suspect it's an older fridge, that uses a good bit of energy. I've run a fridge that uses about 800 watt hours a day on 4 golf cart batteries and 1000 watts of panels without any generator time. I'd know because I'd have to go out and buy a generator!  My current full sized fridge uses about 2Kwh's in the summer and around 1.2Kwhs in the winter/cooler months when it is typically in 60 degree room.

    You have a somewhat unbalanced system, consider that you have a 20Kwh battery bank, and perhaps as much as 1000 watt array. I currently have a 16 kwh battery bank and a 4000 watt array. 




    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • EstragonEstragon Posts: 2,456Registered Users ✭✭✭✭
    Just a thought on the second controller, is it booting fully on battery power alone before seeing pv power? Some CCs can get into wierd states if booted seeing panel voltage.

    It aint pretty, but you could make buss bars by flattening copper pipe, drilling holes, and bolting wires.
    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
  • mcgivormcgivor Posts: 1,903Solar Expert ✭✭✭✭
    edited March 16 #14
    @Christine said,  My friend and helper has been advocating for an MPPT controller and showed me a web page claiming that I'd immediately increase my power by 30%.   I'm not sure that the 30% is an average, maybe a max during certain daytime conditions when you produce and use power?    

    When using MPPT, the panels should be closely matched or ideally identical, unlike PWM where panels of various wattage can be paralleled as long as the voltage is close, MPPT need to be in series to achieve a voltage higher than the nominal, generally about double, with wattage/current very close, so having various different panels can complicate things, It's not a simple exchange is what I'm attempting to circumlocute, 30% increase is a bit of a stretch.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • ChristineChristine Posts: 14Registered Users ✭✭
    Estragon said:
    Just a thought on the second controller, is it booting fully on battery power alone before seeing pv power? Some CCs can get into wierd states if booted seeing panel voltage.
    It's still disconnected, but I will make sure to boot on pv power only.
    It aint pretty, but you could make buss bars by flattening copper pipe, drilling holes, and bolting wires.
    I'll keep that in mind.   Thanks for your tips!
  • ChristineChristine Posts: 14Registered Users ✭✭

    mcgivor said:

    When using MPPT, the panels should be closely matched or ideally identical, unlike PWM where panels of various wattage can be paralleled as long as the voltage is close, MPPT need to be in series to achieve a voltage higher than the nominal, generally about double, with wattage/current very close, so having various different panels can complicate things, It's not a simple exchange is what I'm attempting to circumlocute, 30% increase is a bit of a stretch.
    That's really important to know since I have all different panels.    When my friend gets back we'll test all the individual panels.  Eventually all the old panels will go on camper / greenhouse systems, but until then it's PWM.  Thanks for the info!
  • ChristineChristine Posts: 14Registered Users ✭✭
    edited March 17 #17
    Photowhit said:
    With panels designed for the battery voltage of your system, there may be a 10% advantage with MPPT type charge controllers. We've actually had a major designer say that here.
    That's about what I expected.
    and recently 3 cheapo 150 watt panels. 

    Are these the panels on the Morningstar controller?  Do they produce 17-19 volts or 26-31 volts VMP? The voltage may be too high  for the Morningstar controller.150 watt are usually in the 17-19 volt range, but worth checking, particularly if they are older panels (since they were gifted to you it's worth checking)

    They were not gifted, I just bought the first two recently because they were so cheap (before the tariffs) and a 3rd one I just got a couple weeks ago.  And yes, they were on the Morningstar and we'll check the voltage next week.

    "Are they 60 cell panels or 36 cell panels?"  How do I find out?

    Usually you don't want to double your storage capacity without doubling your charging capacity, don't want your system to be out of balance. Looks like you will need frequent charging from your generator. Many/Most battery banks die from chronic under charging!

    I would have rather you be 'over paneled' than have too little charging capacity. As I've note 8 strings of batteries will create problem particularly as they age. This site talks about the reasoning and maintaining equal resistance through each string;

    http://www.smartgauge.co.uk/batt_con.html

    I got that many batteries because I didn't want them to "die from chronic under charging" and I wanted them to be all the same age instead of adding more later.

    So now I'm working on getting more panels, can buy them one at a time.

    I don't really like having the power on all night.  Until I started running the fridge all the time I pushed a button by my bed to turn off the inverter and it was so nice to know that nothing was running down the batteries (like a broken garden hose causing the pump to run).  I still try to unplug the water pump at night so avoid water disasters, but don't always remember.

    Cheap inverters can be expensive! LOL. They tend to be inefficient and if it is a Modified sine wave inverter, it will actually use more energy with things that have motors and shorten their lives due to the extra heat. Might be worth checking what the inverter uses while idling and it's efficiency in converting DC to AC.
    When I bought my 3000 watt inverter it was under $150.   The lowest priced pure sine wave inverter was around $2k and only 2000 watts, not enough to start the water pump.  Even at 3000 watts it'll trip when someone puts too much pressure on the miter saw, especially if the fridge or washer are running too and I always recommend unplugging the water pump if we saw a lot.

    "Fortunately" my tools are more likely to die from sitting outside unprotected than bad power.    And my computers have been doing well, maybe because the notebooks have the transformers.  The fridge and freezer worry me most.   I saw a $500 pure sine wave inverter last year and was surprised how prices came down, but even that isn't in my budget, and only 2000 watts too.

    I don't know what your additional loads are, or where you are located in terms of how much sun you get, I suspect between the dust on the batteries, building with adobe and wide vistas, you live in an area with a good bit of sun. I suspect you have enough array to run a fridge as the major load without running a generator. I also suspect it's an older fridge, that uses a good bit of energy. I've run a fridge that uses about 800 watt hours a day on 4 golf cart batteries and 1000 watts of panels without any generator time. I'd know because I'd have to go out and buy a generator!  My current full sized fridge uses about 2Kwh's in the summer and around 1.2Kwhs in the winter/cooler months when it is typically in 60 degree room.

    You have a somewhat unbalanced system, consider that you have a 20Kwh battery bank, and perhaps as much as 1000 watt array. I currently have a 16 kwh battery bank and a 4000 watt array. 

    I'm north of Kingman in the desert and haven't seen as much sun as I'd like to this last month!   Had an interesting discussion last summer with a local whose system production greatly improved when he oriented his panels east, it's just so hot here during the day.

    My side by side fridge is 10 years old and a few months ago I was eyeing a new fridge that had 2 freezer drawers below the fridge, MUCH more efficient.   If I saw it again for under $800 I'd put it on my Home Depot card with no interest for a year.

    Been using the Kill-a-watt gadget because I'd really like to know what the fridge uses, but the power has been off so many times lately, wish that thing had a BATTERY so I didn't always lose the totals.

    My first priority is to get the 3 new panels on the Morningstar going again, was way too windy today, hate that wind!  Maybe tomorrow.  

    Then I'll see how the system does.  Ideally my batteries are full by noon and then we do laundry, saw, etc.

    I know one thing for sure, anything I'll buy has to be able to go to 24 v, as that's definitely my next big solar project. 

    Sure appreciate all the help here!
  • mcgivormcgivor Posts: 1,903Solar Expert ✭✭✭✭
    edited March 17 #18

    @Christine said "Are they 60 cell panels or 36 cell panels?"  How do I find out?

    The cell count is actually the square/retangular cells when looking at the panel 6 ×10 would be 60 cell or 6 ×12 =72 and so on, with PWM the optimum would be 36 cell or 72 depending on nominal voltage, 36 for 12V, 72 for 24V , 60 cell are GT (grid tied) panels, which can be used with MPPT charge controllers but are not recommended with PWM due to the voltage maximum power (VMP) being too low a voltage, applicable to 24V nominal systems and too high a voltage for use with a 12V nominal PWM  system. It dose sound a little confusing at first I understand, but wattage wise, a 150W panel could be a 36 cell, the rated wattage will differ between mono and poly crystalline, mono are identified by cut off corners of the cells, but essentially they both perform well. Hope you understand the explanation, feel free to ask questions if in doubt, there are many here willing to share information gathered from many years of experience and it's all free.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • mike95490mike95490 Posts: 7,713Solar Expert ✭✭✭✭
    You misunderstood regarding connecting the Controller.
    Connect the Controller to the Battery first (even many old PWM controllers need to boot) and after a minute, connect to the PV

    Batteries, 2 of them or 20 of them, if not fully recharged at least 2x a week, sulfation sets in and you ruin the batteries.  You must keep them charged to prevent sulfation, 
    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
    gen: http://tinyurl.com/LMR-Lister ,

  • ChristineChristine Posts: 14Registered Users ✭✭
    @mcgivor, they're mono, and it was windy and cold all day again, I'll have a look hopefully tomorrow.

    @mike95490, I understood about the Morningstar connection, but thanks for the reminder.  Will definitely connect the batteries first.

    And regarding the batteries, that's why I'm running the generator so much, and they never got full last night.   I don't get it. The day before it was cloudy and they were full after a few hours and I was so happy.  Then sunshine, no laundry or sawing, and they're stuck at 3 blinks.  Have to figure out what's wrong.
  • BB.BB. Posts: 27,578Super Moderators admin
    Do you have a DC Current Clamp DMM (digital multi meter)?:

    http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P (~$60 and "good enough" for our needs)
    https://www.amazon.com/gp/product/B019CY4FB4 (better meter)

    Current Clamp Meters are very easy and safe to measure current anywhere/anytime in your system. When trying to figure out charging current (solar panels, genset, etc.) questions... It is very nice to have an independent method to confirm everything is working correctly (remember to have good batteries in your DMM... Many will give "weird" readings when the batteries are going dead--Sort of repeatable but readings don't make sense).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChristineChristine Posts: 14Registered Users ✭✭
    @BB.   I don't have one of those, have a cheapo DMM somewhere, but will see what my friend has when he comes back this week.    Something just isn't right somewhere in my system.  The 450 watts new panels are not connected, 5 blinks at noon, but the generator can run for 8 hours and not get above 3 blinks, even WITH the new panels -- except the other day when they were full after a few hours.   

    Hope we'll have some nice days soon. 
  • westbranchwestbranch Posts: 5,048Solar Expert ✭✭✭✭
    re read your initial post and when I read it the first time, I did not see any mention of a combiner box and to do the job right you should have a C-box for each of the  controllers. the "joining of 'ALL' the negatives would first be done in the respective C-boxes leaving only 2, 1 from each C-box , to be connected to the battery neg post....the benefit of a C-box is that each panel or string of panels would have a Circuit Breaker for safety and , if a string of panels, when one panel goes bad it does not damage the rest of the string.
    Here are some choices  (they sell for less at this Forum's  Sponsors store)   http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=9&productCatName=Combiners

     
    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, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MichaelKMichaelK Posts: 75Registered Users ✭✭
    It is so hard to diagnose what's going on in part because you just don't have the right tools to see what's really going on.  I'm going to give you three suggestions that you can pick up inexpensively.  I'll list them in order of priority.

    1) A multimeter:  Nothing fancy, just get something off ebay for 5-10$.  Something like this.
    https://www.ebay.com/itm/Digital-Voltmeter-Ammeter-Ohmmeter-Multimeter-Volt-AC-DC-Tester-Meter-Backlight/152950739997?epid=25006634248&hash=item239c93141d:g:xxIAAOSwUN9ar2ob

    2) Battery Hydrometer:  Judging battery charge by the number of blinks is just sad.  The gold standard for determining the state of your batteries is with a hydrometer.  You simply suck of some of the battery fluid with the bulb and see where it lines up.  A healthy,  fully charged battery should have a reading around 1.290.  The BEST way to determine state of charge is with one that compensates for the temperature of the battery, like this one.
    https://www.ebay.com/itm/Temperature-Correcting-Battery-Hydrometer/253473883908?hash=item3b04388704:g:SIYAAOSwho1an~h7
    A multimeter can be used to determine the state of charge of a RESTING battery, but it's a poor second choice.

    3) Clamp meter:  Quickly determines the amps flowing through a wire.  Cheapest ones read AC current only.  Don't get that.  The next step up is a DC/AC meter.  This is the one I have.
    https://www.ebay.com/itm/UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-Tester-Meter-DMM-CE-AC-DC-Volt-Amp/252445352747?hash=item3ac6ea632b:g:fCQAAOSwHjNV99RG

    A more expensive model from the same company can determine "in-rush" current.  That's the amount of electricity a motor pulls the first half second or so when it's just starting.  That number is typically far higher than the "running amperage".  I have this one.
    https://www.ebay.com/itm/UNI-T-UT216-Series-True-RMS-Digital-Clamp-Meter-Multimeter-AC-DC-Current/391909032552?hash=item5b3f994268:m:mn6k7UV4UQ0mOKu0rsjoyyg
    I've compared this model side by side with a very expensive Fluke meter and they are accurate to within 1% of each other.

    At the very least, get the multimeter, and the hydrometer, and people here can much better guide you through the troubleshooting process.


    15 Renogy 300w panels,  Midnight 200 CC, 8 Trojan L16 batteries, Schneider XW6848 NA inverter, AC-Delco 6000w gen.
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