SB2000E problem

I ran into a SERIOUS problem with my new Blue Sky 2000E.

After several days of low sunlight, the bank discharged to the point that the refrigerator wouldn't start. Unfortunately, my Norcold refrigerator doesn't have an under voltage protection relay - so it tried, and tried, to start. Eventually draining the battery bank to zero volts.

If the fullness of time, the sun came out again. Unfortunately, even though there was lots of PV power available, my Blue Sky controller is powered from the battery bank - so it had stopped sensing PV voltage and just shut down.

After 2 days of bright sun, the bank should have recovered - but, instead, it remained at zero volts.

I jump started the controller with a backup battery and after about 2 days, the bank is back to nearly 13 volts.

I've ordered a under voltege relay (ELK-912) and corresponded with Blue Sky.

My conclusion is, the Blue Sky 2000E is not designed for unattended operation. It must be protected with under voltage protection on the load to function. The device is unacceptable for Marine use - lacking a dead start capability required for alternators (by the USCG).

I don't know about other brands - but all things being equal, you are better off with a diode than the Blue Sky 2000E in a marine application.



  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: morningstar or blue sky???


    This is not really the fault of the Blue Sky controller... Even if it had a LVD available and connected, your Lead Acid batteries would pretty much be toast anyway in overall life (discharging below 50% really shortens lead acid battery life, and discharging to zero really kills them).

    Some AGM's are spec'ed down to support State of Charge down to 20%--but really deep cycling still will take a toll on their life too.

    The LVD system you are installing will, at least, work around the issue that the solar controller not starting with a dead battery bank--but a battery monitor which actively monitors the battery banks SOC--would really extend the life of your battery bank--of course, at the expense of the food in your fridge (when it shuts off the power to your appliances).

    If you need true unattended operation, you will need a backup power source and protection against deep cycling the battery bank. A battery monitor would be a good way to go.

    New Battery Monitor from Xantrex (not quite shipping yet?):
    Defining the amount of energy available in a battery is a complex task since battery age, discharge current and temperature all influence the actual battery capacity. High performance measuring circuits, along with complex software algorithms, are used to exactly determine the remaining battery capacity. A new shunt selection feature enables the LinkLITE to measure currents up to 1,000Amps respectively.

    The LinkLITE selectively displays voltage, charge and discharge current, consumed amphours and remaining battery capacity. Using a clear backlit LCD Display and an intuitive user interface, all parameters can be recalled with just a button press. A second battery input is also provided to monitor voltage on a second battery.

    It is equipped with an internal programmable alarm relay, to run a generator when needed or to turn off devices when the battery voltage exceeds programmable boundaries.

    Also, it sounds like your battery bank (or solar panels?) might be undersized for the job. Normally, we here recommend a battery bank that is 6x your normal daily load (3 days of no sun and only discharge your bank to 50% level). If your system went flat in two days--either the battery bank is on the small size and/or the batteries will not fully charged (undersized solar panels?).

    Of course, on a boat, you have space and weight limitations (and can't always point panels at the sun)--so you are left with the limits set by the location.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: SB2000E problem

    most controllers do run from the battery with some exceptions of course, but the point at which the controller can't function is so low the battery(s) are probably toasted by then. as said by bb that when you discharge a battery too far it is your responcibility and not the fault of the controller. an lvd may help you if it is programable in it's lvd setpoint as many put that point at 10.5v and the battery is officially doa at that point making it useless.
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