MPPT MT-5 Meter and Amps Input?

timsim00timsim00 Registered Users Posts: 15 ✭✭
in Solar Beginners Corner #1
Hello.  I have a Renogy 40A MPPT CC with an MT-5 tracer to reach different inputs/output of the charge controller.  I have 4 100W 12V panels in parallel to my charge controller.

My question is the amps IN from the panels being read by the meter.  At peak sun time I am pulling in roughly 20+ Amps.  As my batteries fill, and need less current from my panels, would this meter reading change as the draw from the CC changes to accommodate my batteries need?

EXAMPLE:

Batteries at 80%, AMPS @ CC input is 20 amps
Batteries at 99%, AMPS @ CC input decreases?

Any ideas?
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Comments

  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    That's the way my batteries work, about half way through Absorb, the amps start declining.
    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 ,

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  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited March 2017 #3
    You kind of answered your own question in a way, as the battery approaches it's maximum capacity, the current will drop as it becomes saturated, if the CC has an end amp programmable feature, at approximately 2% of the battery Ah capacity, is where you would want to end the absorption and transition to float as there is no benifit  of further charging, other than producing gas, consuming water and possibly damaging the battery, assuming they are FLA, sealed batteries would suffer even more.

    One observation is you have all your panels in parallel, which kind of defeats the purpose of having a MPPT CC in the first place, ideally you would want the input voltage to be double the battery voltage to take advantage of MPPT, so wiring 2 panels series  and 2 strings parallel would be benificial in low temperature and low sunlight conditions, such as overcast days.

    @timsim00 said
    Batteries at 80%, AMPS @ CC input is 20 amps
    Batteries at 99%, AMPS @ CC input decreases?

    I'm assuming the input to the CC is in proportion to the output of the CC .

    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • jonrjonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited March 2017 #4
    >  benificial in low temperature

    Isn't the series wiring of the panels most likely to help when the panels are hot?

    I am available for custom hardware/firmware development

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  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #5
    jonr said:
    Isn't the series wiring of the panels most likely to help when the panels are hot?
    If the panels were hot and the VMP was to drop below the requirement to charge the battery, having them in series would also be benificial. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • softdownsoftdown Solar Expert Posts: 3,689 ✭✭✭✭
    #6
    I suspect that Mcgivor probably nails it with his explanation.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • PhotowhitPhotowhit Solar Expert Posts: 5,989 ✭✭✭✭✭
    #7
    timsim00 said:
    Hello.  I have a Renogy 40A MPPT CC with an MT-5 tracer to reach different inputs/output of the charge controller.  I have 4 100W 12V panels in parallel to my charge controller.

    Any ideas?
    This would be improper wiring for a MPPT charge controller. They need to have higher voltage to work with.

    Panels should be 2 in series, with 2 strings parallel, to work effectively and most efficiently.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • jonrjonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited March 2017 #8
    As Mcgivor says, only if the VMP drops below the charge controller/battery requirement.  If not, then the lower voltage of parallel wiring usually very slightly improves efficiency (ignoring wiring losses).    But I agree that for most "12V" panels, hot panel MPP can drop to 16V, which may be too low for peak efficiency, especially with cool batteries.  2 in series makes sense here.

    I am available for custom hardware/firmware development

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  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #9

    I can help with this  I have used this controler for 2 years . 
     400watts getting 20 amps is good power . 
     My amps drop off earlier then I would like and I go into float at 13.6 volts . 
     My amps hover at 1.5 to 2 amps at 13.6 volts .
     The amps don't seam to tapper off much I go from 8/9.5 amps 
    in full sun  laying all most flat facing south west . 
     I have 220 watts . 
    To 4/5 amps to the 1.5 to 2 amps float 
      Don't worry about the mt5 it doesn't really read  accurately .
      I seam to go into float early controler reads 99/100% full but 
     my SOC reads 12.6  95% ?
     I am always useing power so that seems to fug the controler up a little .
     If you put a good load on the battery,the charger will leave float and  the amps rise up to power it . 
     The temp  sensor on the charge controler really messes with the charging if the battery's and controler aren't at the same temp . My battery are in a vented box to the out side 
     the controler is in a un heated area in my trailer the battery wouldent really charge up good 
     I had to run a genarator and charger .
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #10
    I see 17 v in good sun and the battery's get from 13.6 to 14.5/14.6 most of the time . 
    If you don't dran down the battery  10% the charger just floats all day . 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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