85 V solar panel to 12 V Deep Cycle Battery via 150V max MPPT unit

Geo_OcnGeo_Ocn Registered Users Posts: 2
To start, I must admit I know very little about working with electrical current and batteries, less about using a multimeter and even less about solar panels.  Now that I've gotten that confession out of the way, can anyone help me with my issue?  I purchased a MPTT that has a 150V max rating.  I checked the output of the solar panel using a multimeter (hopefully correctly) and believe it was giving me a reading of 85V which met the rated output on the solar panel. When I connected the solar panel to the MPTT and took a reading from the terminals that are supposed to go to the battery, I was not able to get a voltage reading.  Any ideas as to my issue and what I was doing incorrectly?


  • mike95490mike95490 Solar Expert Posts: 8,067 ✭✭✭✭✭
    A MPPT controller has a small computer internally, and is powered by the battery.

      You connect the battery first, let it boot up for a minute, and then connect the solar, and you will shortly see the battery voltage start to rise.
    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 ,

  • Geo_OcnGeo_Ocn Registered Users Posts: 2

    Thanks. When I didn't get the reading I expected out of the MPPT, I didn't want to take a chance on damaging the battery so I never connected the MPPT to the battery. Now with your input, it makes sense that the MPPT needs a power source to activate.

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