Sun Saver 10 Question and DC gate opener

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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #32
    Re: Sun Saver 10 Question and DC gate opener

    what are the specs for those panels? I suspect they are too small for the usage

    If you do not have at least (@24 v rating) 3amps, better at 5amps, best at 6.5 (5 - 13% of batteries Ahr rating)
    And at least 1.2 times the number of watthours used by the motor, put back into the batteries it is going to fail in the fall/winter times.
    Please advise of the watt rating fr the motor... THEN there is the surge load to start the motor that can be3 to 5 times the watt rating of the motor.

    add: during the day the panels were probably powering the loads, and maybe some from the batteries too
    Hope this starts to explain your problem.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #33
    Re: Sun Saver 10 Question and DC gate opener

    Welcome to the forum.

    Let's see, the panels couldn't keep 25 Amp hours @ 24 Volts charged in Winter so they switched the batteries for 18 Amp hours @ 24 Volts and now that doesn't work.

    The two 25 Watt panels are probably 12 Volts, meaning a total of 1.4 Amps of current @ 24 Volts. Not really enough to recharge either battery set once Winter comes. When the sun is up the panels can keep the Voltage high enough to run the gate but there's no longer any battery reserve.

    The missing part of the formula is the unknown amount of power used between charge times that the panels have to replace. But it sure sounds like your still getting chronic deficit charging.

    Were it me, I'd switch back to the 25 Amp hour batteries and get some more panel on them. Like about 50 - 60 Watts worth. Then, hopefully, there's be enough reserve capacity in the batteries to handle a couple of cloudy days and enough panel to recharge afterwards.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #34
    Re: Sun Saver 10 Question and DC gate opener

    It sounds like "deficit charging"... Basically, full batteries lots of sun, system gets back to near 100% charge every day...

    As the seasons progress, the load takes 5% of the battery charge and the solar panels return 4% of charge. As this goes on the average state of charge of the battery bank slowly falls, down below 75% SoC, to 50%, to 20% and so on.

    There are several "risks here"... One is the longer the batteries sit at less than (full charge), they slowly sulfate. The deeper they sit at less than full charge (below ~75% SoC, the faster they sulfate).

    The other issue is when the batteries go below ~20% SoC, the battery runs the risk of one cell "going reverse charged" (5 cells still have power, one cell is dead, and effectively is "reversed charged" by the other 5 cells). All (almost all?) battery chemistries "die" when reversed charged.

    So--Your solution is not (necessarily) a larger AH battery bank, but a larger set of solar panels (and they have to be the "right voltage" for the setup--With a charge controller, that is usually Vmp around 17.5 to 18.6 volts or so for a 12 volt battery; and 35 to 38 volts for a 24 volt battery bank).

    Another failure mode is Over Charging which "boils" the batteries dry (and erodes plates, causes positive grid corrosion, etc.)... This can happen from a failed charge controller (too high of charging voltage). Or some system designs don't use a charge controller and "over charge" the battery bank with just the solar array.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #35
    Re: Sun Saver 10 Question and DC gate opener

    To Wildchilli

    Perhaps the system you purchased is too small for your needs? Gate systems are priced according to the average number of full cycles they can perform with the 'weight' of the gate. Our Apollo Opener is designed for gates that weigh between 200-600 pounds, and is rated to push that weight on an average day, between 25-30 times. We don't have alot of traffic going when the sun is down, so our light-duty system was cheaper. Even so, the installer doesn't have a clue about batteries-he just shoves the largest Ah he can squeeze in the box, and pairs it with a 10 Watt panel. Because of this, our last 185Ah battery lasted almost 3 years before it fully failed.

    Your sytem seems to be alot more efficient, but underpowered.
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