Controller

yeomanyeoman Registered Users Posts: 4
I have a new 5-45w controller. If I connect a known to be good 12v 7ah battery to the controller input side, the yellow charging light blinks, however, I get 0 voltage reading on the output side. Same when I connect my 20w panel to the controller. Panel is putting out 15-17v depending on sun angle, yellow charging light blinks, but 0 on output side of controller. Is this normal?

Comments

  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    You should always connect a battery on the output side of a controller first, let it boot up fully, and only then put pv voltage on the input side.  I wouldn't put a battery on the input side.

    Pv voltage on the input side first can make the controller boot in unexpected ways.  Also, the controller likely has a low battery cutoff voltage to protect itself, so with 0v on output terminals it's likely in LBCO.
    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
  • yeomanyeoman Registered Users Posts: 4
    I see. So if I first connect a battery to the controller output side, then panel to input side, should I expect a reading above say 13v at the battery? I was getting readings around 13.7 with this setup before corrosion ruined the previous identical controller.
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    The voltage at the battery will depend on its state of charge.  For example, at rest, a 50% SOC lead acid battery will have a resting voltage of ~12.1v.  When charging, this voltage will slowly rise until set absorb voltage (eg 14.x) is reached, about 85% SOC.  When absorb is completed, likely from a timer (~2-3hrs) expiring, it should go to set float voltage (13.x) for as long as there's sun on the panels.
    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
  • yeomanyeoman Registered Users Posts: 4
    Thanks, With 24 12 volt batteries in my life I'm pretty familiar with SOC. I'm just trying to prove the panel is functioning through the controller.
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    If you have a DC amp meter you should see ~1a current flowing to the battery when the controller starts bulk charging?
    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
  • yeomanyeoman Registered Users Posts: 4
    I have a multimeter so I can see if that works if the sun ever comes back out. Thanks
  • BB.BB. Super Moderators, Administrators Posts: 32,923 admin
    Longer term, you may want to look at a DC current clamp DMM (digital multimeter). Makes it dead easy to measure current, debug systems, understand what is happening (no disconnecting of cables, won't blow a meter fuse, much safer, etc.)... A couple of links to start with:

    https://www.amazon.com/gp/product/B019CY4FB4 ($100 medium price)
    https://www.amazon.com/gp/product/B07546L9RT ($50 "good enough")

    Note, there are AC only clamp DMMs, and AC+DC current clamp meters. Both are fine meters, but for our needs, the AC+DC current clamp DMMs are what work best.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Clamp meters are not very good at fine, small measurements, interference and drift are usually more than the measurement <1A
    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 ,

  • GrahamlenGrahamlen Registered Users, Users Awaiting Email Confirmation Posts: 1
    Would measuring more precise than around 1A in a case like this be important?
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Considering a 20w panel connected to a 12v battery isn't likely to produce much more than about 1amp, a +/-1a accuracy reading isn't too helpful. 

    Lots of multimeters can test ok in this amp range, but need to be properly set and put physically in the circuit.
    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
  • jonrjonr Solar Expert Posts: 1,386 ✭✭✭✭
    Get a volt meter with sufficiently low voltage range and any section of the wiring will be a fairly accurate current shunt.

    I am available for custom hardware/firmware development

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