Solar Wind Help Plz

sbassman
sbassman Registered Users Posts: 4
Hi:
Why does my 12v turbine not charge any higher than 14v? It puts out 12-30v with no load. Mppt solar controller charges 3-12v Deep Cycle batts to 13.2v . Pma connects thru a diversion controller at 14.5v then directly to batts or 900w dump load. Batteries voltage increases 1-2v when spinning avg speed but days of wind dont add to them much. No ampmeter available that will measure up to 30a. !0 ga. Wire througout and diodes on pv's. Should I buy a inline ampmeter?



Greenenergy controller, 2-50w pv's, 3000w inverter, 3-marine deep cycle, grid pwr II 250w, 900wdump load

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Solar Wind Help Plz

    Welcome to the forum sbassman.

    I will try to help with your questions--but I am a bit confused.
    sbassman wrote: »
    Why does my 12v turbine not charge any higher than 14v?

    A turbine is typically a permanent magnet alternator (PMA)--Which is pretty similar to your car's alternator (a car alternator uses an electric coil instead of permanent magnets--PMA alternators are more efficient, but cannot be regulated by varying the field current).

    The usual HAWT (horizontal axis wind turbine) has a rectifier (AC to DC diode bank) which then connects directly to the battery bank. The output voltage of the PMA is then fixed by the battery bank voltage (state of charge, how much load/charging current/temperature of battery bank, etc.).

    The battery bank is what "regulates" alternator's output voltage. The standard method is to use a "dump" or "shunt" controller that takes the excess current (if the battery is >14.5 volts, it turns on and dumps the current into a resistor/heater bank until the voltage falls to 13.8 volts, then the dump controller turns off until the voltage rises over 14.5 volts again).

    HAWT's need to be "loaded" all the time to limit the maximum RPM of the turbine... If the turbine is "unloaded" (no electrical loading), it can over-speed and self destruct.
    It puts out 12-30v with no load.

    Yes, the open circuit voltage of an alternator is proportional to the RPM (and design of the alternator). And at very high RPM's, alternators can output much higher voltages (even over 100 volts in some cases). But because there is no current flow--there is no "load" on the turbine (and it can over-speed). And, even if the turbine outputs 30 VDC open circuit, it really does not mean anything--What current the alternator outputs at XXX RPM at ~12-14.5 volts is the important part.
    Mppt solar controller charges 3-12v Deep Cycle batts to 13.2v .

    Battery voltage is a function of charging/discharging current and state of charge (temperature also plays an effect too).

    Nominally, a "resting battery" will read somewhere between 11.5 and 12.7 volts (from ~20% to 100% state of charge). A battery will be charged (Bulk charge is maximum available current) until the battery reaches ~14.5 volts (Absorb voltage), then held there by the charge controller for 2-6 hours. Then the charge controller will drop down to ~13.6 volts (Float voltage) until the battery is discharged again.

    New poster "leaf" has a really nice set of charts that compare battery voltage against different rates of discharging and charging (as well as resting voltage readings).
    leaf wrote: »
    Am trying to upload the charts I am using...

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    attachment.php?attachmentid=3655

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    If the battery does not reach ~14.5 volts and is held there for a few hours at least a couple times a week, then the battery bank runs the risk of "deficit" charging (too much load, not enough charging energy) and can eventually cause the battery to have early life failure.
    Pma connects thru a diversion controller at 14.5v then directly to batts or 900w dump load.

    Usually, the turbine connect directly to the battery bank (through rectifier and fuse/circuit breaker). The "diversion controller" is simply connected to the battery bus--and turns "on" when the battery is fully charged and the "excess current" from the wind turbine (or other charging source) needs to be diverted to the waste load (electric heater).

    The Watt rating of the load/diversion controller should be enough to take >100% of the wind turbine's maximum output to (safely) prevent the battery bank from over charging.
    Batteries voltage increases 1-2v when spinning avg speed but days of wind dont add to them much.

    Batteries are very sensitive to operating voltage. If you do not fully recharge them with the proper voltage (and current), they will not last long. You need to get a battery bank to ~14.5 volts for a few hours to fully recharge the battery bank. If you have a battery at 12.3 volts and raise its voltage to 13.3 volts--the battery is really not even being charged--It is just being "floated" or prevented from further discharging.
    No ampmeter available that will measure up to 30a. !0 ga. Wire throughout and diodes on pv's. Should I buy a inline ampmeter?

    There are many different instruments for measuring energy flow through a battery based power system. Yes, you can purchase a in-line current meter, or get a current shunt and meter, or a Battery Monitor (which is designed to tell you the battery bank State of Charge and other measurements.

    For debugging a DC power system, a DC Current Clamp Meter (like this ~$60 one from Sears) is really handy (this really a digital multi meter). Note that DC Current clamp meters are much easier to use and much safer than the usual in-line current meter (like a DMM) where you have to "cut" the wire and insert the meter.
    Greenenergy controller, 2-50w pv's, 3000w inverter, 3-marine deep cycle, grid pwr II 250w, 900wdump load[/QUOTE]

    Don't know the size of your turbine--But this looks to be an "unbalanced" system. Very large AC inverter, hardly any solar panels for charging, and "marine" batteries which are not really designed for deep cycling (they may not last very long if deep cycled often).

    Also, it can be a bit tricky mixing Solar Panels plus solar charge controller plus a shunt controller. Things can get a bit confused (i.e., the solar charge controller is trying to recharge the battery bank while the shunt controller is trying to drop battery bank voltage/shunt charging current to load).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Solar Wind Help Plz

    One very likely reason is that you're turbine, as usual with small scale wind, is not putting out anywhere near the hyped (dare I say lies) and promoted power outputs claimed by the manufacturers and promoters of small scale wind turbines. Been there, learned the hard way.
    As I've so often said before - - very few and far between were the days when my turbine produced any usable power at all, but on the other hand, very few and far between were the days when I don't receive at least some usable power from solar.
    Almost without exception, truth be known, small scale wind is a SCAM!
    I know that sounds pretty blunt, but it's the unfortunate stark truth :cry:
    Beyond that, like "BB" says, you're system does sound quite unbalanced, with a relative monster 3000 watt inverter, and only two 50 watt PV. These panels will be hard pressed to even supply enough power to keep that big inverter running, not to mention any loads being run by it. And of course, like "BB" mentioned - - the batteries.
    All that said, you have come to the right form for good, honest, experienced, been there help and advice, and we welcome you to the form. There is much information here, much reading here, that will point you in the right direction.
    Peace
    Wayne
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Solar Wind Help Plz

    Besides which, it's not supposed to.
    The "free speed" Voltage of a turbine (no load) is like the Voltage open circuit on a solar panel; much higher than what you get when a load is applied. With a load connected you will not see this high Voltage but rather the battery Voltage up to and no higher than Absorb level (when the dump load connects to 'syphon off' surplus power).
    The correct charging (Absorb) Voltage for a 12 Volt system is 14 to 15 Volts.

    If you're not getting much charge from the wind turbine it isn't surprising. As Wayne said, they rarely perform as advertised. In your case you have three batteries in parallel (bad idea) which is probably around 270 Amp hours @ 12 Volts. The most your turbine can put out (if I'm reading the specs right) is 250 Watts. SO if it was working perfectly you might see 17 Amps, or enough 'ideal' charging power for 170 Amp hours of battery. At that rate you would still have a viable charge for your batteries of about 6% rate. In all likelihood, though, it's working at about 50% capacity or possibly less. That puts it in the "under 5% minimum rate" category so it would not actually do much for your battery bank.

    I think getting an Ammeter on its output would provide you with some valuable information as to just how useful your turbine really is.
  • sbassman
    sbassman Registered Users Posts: 4
    Re: Solar Wind Help Plz

    Thanks for detailed help. I know I need to rethink my setup. I am going to read more on the site then I hope to talk to you all later.