Outback fleximax 80

gavgav Registered Users Posts: 10 ✭✭
 Hi again can u lower the target voltage down for the bulk charging on the outback 80?


  • petertearaipetertearai Solar Expert Posts: 446 ✭✭✭✭
    yep  .. its  called the absorb voltage 
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
  • gavgav Registered Users Posts: 10 ✭✭
    Thanks so it won’t go above absorb voltage point when in bulk charge?
  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    When it gets to the absorb voltage setpoint (temp compensated), it will transition out of bulk to absorb. In absorb, voltage is held constant at the setpoint, and current drops off as the battery get closer to fill.

    The bulk part of the cycle is defined as a constant current (limited by available solar or a controller setting) with voltage rising up to the absorb setting, so no, voltage shouldn't go above that in bulk.
    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
  • BB.BB. Super Moderators, Administrators Posts: 31,153 admin
    Note that some controllers have a "bulk" and an "absorb" setting... I would presume that it could working something like--Charge to Bulk (current limited) to 14.9 volts. When Bulk is reached, to to absorb setting and charge at 14.7 amps for X hours (or until ~1-2% rate of charge is reached---Tail of charging current). Others just have an Absorb setpoint (battery is "bulk" charged to setpoint, and then held for X hours, or other like 2% rate of charge, etc.).

    You will sometimes see separate Bulk and Absorb set points and current/voltage setpoints for batteries (there is a whole industry and tech speak for battery (DIN Euro Standards) charging that I am not familiar with at all). For example:


    In general, most battery Mfg. and tech talk assumes you have 24/7  (24 hours a day, 7 days a week) AC mains (and backup AC gensets) so that you can charge according to their "optimum" requirements.

    With Solar Energy, the mapping of solar energy to batteries with a side of loads--The charging is rarely "optimum". And we fall back to "the way it has always been done" with solar...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SurfpathSurfpath Solar Expert Posts: 400 ✭✭✭
    Hi Gav,
    I also have a Outback FM80.  Basically (as has been said in different ways* in this thread) there is no "bulk" voltage to set.  The controller will use MPPT to efficiently bulk charge your batteries in the morning, starting when the sun rises.  It depends on the insolation, but typically I see bulk voltage appreciatively rise around 10:30am, a half hour or so before my system goes into absorb.

    * eg: The bulk part of the cycle is defined as a constant current (limited by available solar or a controller setting) with voltage rising up to the absorb setting
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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