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DC Pump Back EMF

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  • DC Pump Back EMF

    Connecting Shurflow 2088 12V and 5050 24V pumps to solar charge controller load terminals or across batteries connected to controller output. Worried about back EMF, but do now know how much Morningstar TriStar, SunSaver PWM and SunSaver MPPT controllers can handle, or how much the pump produces at turnoff. I would rather not use a snubber diode if not needed. Any experience/ideas?

  • #2
    It the pumps are simple brushed motors, they WILL generate back EMF. Electronic, brushless motors do not generate much back EMF
    However, what you must make doubly sure of, is the inrush starting current (it won't be nearly as bad as a AC motor) and if the
    amp rating on the LOAD output, can safely supply it, Most controller LOAD outputs are pretty small ratings.

    And there is no reason NOT to install a $2 snubber diode to protect a $80 controller, unless you install it backwards.
    Powerfab top of pole PV mount (2) | 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