4 Kw system with dual 6600 magnum battery back up low battery fault

michael99
michael99 Registered Users Posts: 1
in Grid Tie and Grid Interactive Systems #1
Hello, my 4 kw system with dual 6600 magnum battery back up system keeps showing a low battery fault when I run an grid power loss test. The entire system is less than one year old. We had a recent power loss and the battery backup failed. I contacted a tech at magnum, we went through and reset the settings on the router. Everything is working normal until a grid power loss. then the inverter comes on for about 3 minutes and faults out on a low battery shut down. This morning I isolated the sub panel and cut the grid power, the inverter came on but showed a constant battery drain. I then turned on one breaker in the sub panel and volts went below 48 and the inverter shut down. When I brought grid power back on the router went to surge charge for 2 hours and then to float. Any ideas what could be the problem. How far is away from the inverter can you place the battery cabinet? mine is about 20 feet.
thank you
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #2
    Re: 4 Kw system with dual 6600 magnum battery back up low battery fault

    This looks like a battery problem. One of the cells might have gone bad. If you have a multimeter, I would measure voltage on every battery to see if they're all the same. If you have flooded batteries, it would be a good idea to measure specific gravity of every cell with a hydrometer.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #3
    Re: 4 Kw system with dual 6600 magnum battery back up low battery fault

    Welcome to the forum Michael!

    Sorry you are hear with problems. It can be difficult to get yourself dug out of the hole--There are many parts of the system we need to talk about to figure out what is wrong.

    First, can you give us the details about your battery bank? Flooded cell / AGM / GEL / Brand / Model # / etc... AmpHour rating (per battery @ xx volt, series/parallel connections, etc.).

    If these are flooded cell batteries, can you give us the temperature corrected specific gravity readings of each cell?

    And do you have a DC Current Clamp type DMM (digital multi-meter)? If not, I would suggest this one from Sears as pretty cheap and "good enough" for our needs. Being able to make quick/simple/safe current readings (especially if you have parallel battery strings) is really nice.

    With a good/accurate volt meter, can you measure the voltage across each cell (or battery) too. And tell us what state the system is in (charger is floating at 52 volts or what).

    Basically, trying to figure out what the state of charge of your battery bank is. Also, to see if there are any bad cells/electrical connections.

    Next, I would like to know about the other parts of your system. I think what you are calling the "router" is really an AC Inverter+Battery charger. Can you tell us the brand and model number (Magnum is a big inverter/charger mfg...But I do not recognize the dual 6600 model number).

    Do you have any solar arrays/charge controllers connected to the battery Bank?

    Do you have a backup AC generator?

    And can you tell us about the DC cabling side of your system... Wire AWG (American Wire Gauge--assuming you are in California?) and length of cables from battery bank to AC inverter+charger?

    Your first task will be to figure out the battery bank State of Charge (SOC) and if it is low (what I suspect), we need to get it quickly charged back to near 100% SOC (and understand how to get your system to do that). Batteries that set at less than 75% SOC for weeks/months will sulfate and eventually fail (sulfation is when the soft/fluffy lead sulfate turns into hard/black crystals--This removes the lead from future battery chemical reactions and will quickly kill a battery bank--And there is no known "good" way to recover a sulfated battery).

    Unfortunately, you are about to become an expert in off grid/backup power systems. Your first reading material is to learn the details about batteries (read at least the first FAQ):

    http://www.windsun.com/Batteries/Battery_FAQ.htm
    http://www.batteryfaq.org/
    http://batteryuniversity.com/

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: 4 Kw system with dual 6600 magnum battery back up low battery fault

    Welcome to the forum.

    Twenty feet between batteries and inverters could be a problem depending on the size of the wire. This can hurt you both in trying to power the inverters and in trying to charge the batteries.

    Check the battery Voltage at the batteries and at the inverters with the grid off and see what it says.

    If you could give us some more detailed specifications on the system that would help (battery bank size in Amp hours, wire gauge, et cetera).
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  • jaggedben
    jaggedben Solar Expert Posts: 230 ✭✭
    #5
    Re: 4 Kw system with dual 6600 magnum battery back up low battery fault
    michael99 wrote: »
    ... How far is away from the inverter can you place the battery cabinet? mine is about 20 feet.
    thank you

    We also need to know the size of your battery cables to answer whether this is a problem or not.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #6
    Re: 4 Kw system with dual 6600 magnum battery back up low battery fault

    Is this the system you have ?? Using a mini grid with AC coupling to charge the batteries or the Grid ??

    http://www.bluepacificsolar.com/power-center/ac-coupling-6600.html
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