Xantrex C controller uses panel as dump?

KC-watts
KC-watts Solar Expert Posts: 37 ✭
in Solar Beginners Corner #1
Solar power is 60 W panel to Xantrex C-40 controller to 12 V batteries. Solar barely keeps up my cell phone charging /night light hobbyist station, so I plug in a 12 V charger once a week to stir electrolyte at 14.4 V.

Question is, when the bank is charging from the 100 A charger, the C-40 charger starts flashing like it is going to start diverting a load to the solar panels (the diodes?). When the C-40 and 120 V charger are both set to 14.4 V, I can only expect the C-40 to hold off diverting for one hour (as per manual)

Anybody else using the Xantrex C series with a generator/etc and solar panels? For the once a week 120V charge event, I disconnect the C-40 so I don't damage either diodes or solar panel. Thanks
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Xantrex C controller uses panel as dump?

    So are you running your generator out put through the C40?
    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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  • KC-watts
    KC-watts Solar Expert Posts: 37 ✭
    #3
    Re: Xantrex C controller uses panel as dump?

    No the 100 A charger is on a separate circuit to the battery bank (300 A fused).
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #4
    Re: Xantrex C controller uses panel as dump?

    The C-40 cannot be used as both a Charge Controller and a Diversion Controller at the same time. If you have the jumpers set as a Charge Controller the reason the lights are blinking, it is sensing the battery voltage and saying it is seeing Bulk / Absorb Voltage at the battery because of the charger's input to the batteries.
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  • KC-watts
    KC-watts Solar Expert Posts: 37 ✭
    #5
    Re: Xantrex C controller uses panel as dump?

    The setting for Charge/Dump is the same, load control is another setting. When you first connect the battery to the C40 with a resistor bridged across the PV/Dump connections, from an ammeter I see the controller does a quick test to verify a dump load is connected. I hope that is what internally sets the C40 to not start reverse biasing solar panels. Order: connect the battery, wait, then connect the PV. For dump, connect the dump load, then connect the battery. I'm sure it's in the manual, but I just got scared watching charge indicator LED flash faster when a PV was connected.
    I finally tackled the question on this sunny day when I woke to 16.5 V on my PV-battery direct connect. Glad they are flooded cells :)
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  • KC-watts
    KC-watts Solar Expert Posts: 37 ✭
    #6
    Re: Xantrex C controller uses panel as dump?

    I still don't have the two battery chargers, a charger/inverter and the Xantrex C40 + solar panel, connected together. I re-read the Xantrex C35-C60 manual and multiple chargers should have diodes between them.

    Load control and charge control are the two settings. Forget load control as that is a whole 'nuther function. When set on charge control, the internal connections are either RE pos, battery pos, and common. Dump control is similar (same charge circuit setting): dump resistor, battery pos and common, with the RE source connected directly to the battery.

    The question is, and I think I'm getting closer to an answer with use of diodes, will a second battery charger connected cause the C40 to start dumping the current into the solar panel, especially if the absorption stage is miss-matched.
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