Small wind turbine. Charging battery with output?

RoverKRoverK Registered Users Posts: 4
Hi,

I'm new on these forums and I'm experimenting with a bit of an off-grid setup for my log cabin here in Ireland.

I have a 160W solar panel setup with an MPPT charge controller going into a 12v AGM battery. All working grand. Where i'm becoming a bit stuck is when I try to add a wind turbine into that mix.

I bought a Gudcraft / Aleko WGV45W not really knowing a lot about wind turbines and deciding to go for a vertical axis turbine as I have a lot of trees on site. I certainly wouldn't pay that much for this chinese made pile of rubbish again but we learn something everyday. Turbine wise, it's fine, picks up the wind and turns good, and the alternator generates between 8-19vdc on a good wind. The circuitry/controller (small rectifier and a 3A max buck booster to 12v straight, not even higher for charging!) that came with it was no good so I ditched that and put in a 35A rectifier (overkill I know). The turbine CAN produce usable current as when I hook it straight up to lighting with no batteries involved, it powers it easily.

I've tied it into the MPPT solar controller i have hoping it would do something with the output but while it produces volts, I don't think it produces current so won't charge. The problem is (i think) that when I read this voltage on the solar charge controller it's unloaded and it's generating no current.

I'm under the impression that connecting the rectifier straight to the battery would give the turbine a load, and possibly produce usable current? Basically what would be the cheapest/easiest way of getting this turbine to put usable current into the battery?

Comments

  • jcheiljcheil Solar Expert Posts: 719 ✭✭
    Re: Small wind turbine. Charging battery with output?

    Are you saying you tied it into the SAME MPTT controller as the solar panels? If so, that is a serious problem.
    Not only will it confuse the MPPT controller, it might end up damaging stuff.

    Wind needs it's own dedicated controller plus you need a dump load of some kind to get rid of the excess that the wind produces once the batteries are full otherwise you will damage the wind turbine itself.

    A neighbor here had one and foolishly connected it directly to the batteries. Well, sad story, but several weeks later his entire house burned down when the batteries overcharged, exploded and caught fire.

    Disconnect it now!
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Small wind turbine. Charging battery with output?

    Welcome to the forum.

    You've pretty much thrown away your money on that VAWT. For one thing, that style of turbine is less efficient than a horizontal one (HAWT). For another, your "open circuit" Voltage is barely reaching 19 in a good wind, which is about the minimum you'd need to achieve any charging.

    Connecting it to an MPPT controller won't do anything for you, because the Voltage is not high; the MPPT controller could down-convert higher Voltage into more charging current, but there just isn't anything for it to work with. And jcheil is correct; you do not want it on the same input as the solar panel.

    The standard method of connecting a wind turbine is directly to the batteries, then using a PWM type charge controller to a dump load: the batteries 'feed' the controller's input and its output is connected to the dump load. If the battery Voltage goes high the controller activates and sends the excess power to the load, keeping the Voltage regulated at the proper set point. You must use a controller designed for this function though.

    If I'm reading the spec right, that is a 45 Watt turbine? That will only be about 3 Amps maximum @ 12 Volts (hence the controller that came with it) and won't be very useful for charging most batteries as it is bound to be only enough current at most to maintain one 100 Amp hour unit.

    Like so many small wind turbines the thing is a toy, a joke, a useless "pile of rubbish" just as you say.
  • RoverKRoverK Registered Users Posts: 4
    Re: Small wind turbine. Charging battery with output?

    Thanks for that information jcheil, i'll disconnect the turbine from the solar MPPT. I wasn't aware it could damage it like that.

    So do wind controllers actually add a load onto the output as well? So that the turbine produces usable current?

    I'm stuck as to which type of controller to go for. I've had a browse on ebay but it's not too easy to pick a cheap one without looking like it's rubbish.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Small wind turbine. Charging battery with output?

    When charging the turbine will 'see' the battery as a load, because it should produce more Voltage than the battery is at: Voltage differential = current flow. When the battery reaches the set point determined by the dump load controller that will activate and become the load for the turbine's output at the battery Voltage.

    And you're right about buying cheap equipment: you can spend the same money buying the good stuff once or the cheap stuff over and over. Look at Morningstar controllers for quality dump load control. But frankly it's probably not worth throwing more money at that turbine. You could connect it directly without a controller (temporarily) and see how it performs, providing you watch it all the time (Voltage and current levels).
  • RoverKRoverK Registered Users Posts: 4
    Re: Small wind turbine. Charging battery with output?

    Hi Cariboocoot, thank you for the information.

    Unfortunately my site isn't ideal for a HAWT, i'd have had to chop a few trees or go up into the trees above the canopy. They're too tall for me to do that with.

    You're right, it's a 45 Watt turbine. I'm not expecting any more than a few amps out of it, and if it's only enough to keep my battery from discharging on not-so-sunny days I'd be happy. On very dim days when my solar panels only output a few watts, it's still enough for me.
  • RoverKRoverK Registered Users Posts: 4
    Re: Small wind turbine. Charging battery with output?
    You could connect it directly without a controller (temporarily) and see how it performs, providing you watch it all the time (Voltage and current levels).

    If i was to connect it temporarily like this, would the permament resistance of the battery make the turbine produce voltage equal to or higher than the battery? Or am I confused with the way alternators work?

    If i were to connect the rectifier direct to the battery, might there be the possibility of the turbine putting 15+v into the battery on a good windy day when the turbine exeeds say 14.4v? Or would I need a voltage converter (step up/step down maybe?) to keep it at 14.4v for charging?
  • BB.BB. Super Moderators Posts: 26,872 admin
    Re: Small wind turbine. Charging battery with output?

    The "simple" method:

    Turbine => Rectifier => fuse/breaker (protect wiring) => battery bank

    On the battery bank, you would need a "dump load" (i.e., if battery is >14.7 volts charging, turn on a 45-100watt or larger load/electric heater to "dump" excess charging current, when battery voltage falls below 13.6 volts or so, turn off dump load, repeat cycle).

    If your battery bank is >~400 Amp@Hour at 12 volts (assuming 4 amp charging current is less than 1% of battery capacity), you can get away without a dump controller (small amounts of charging current will not over charge a lead acid battery bank--Should still have a dump controller for safety/long battery life... usual safety warnings).

    In the end, unless the turbine is >30' (or 10 meters) higher than the neighboring trees, you will not get a useful amount of power from a HAWT or VAWT--The wind energy has been turned into turbulence and there is simply not harvest-able energy present in the wind.

    That is why everyone is warning you not to dump a lot of money into the wind system. VAWTa (vertical axis wind turbines) are pretty much all marketing hype. There is no area that they are "better" than HAWT (with the possible exception that VAWTs are so inefficient that they cannot overspend in high winds).

    If you cannot get a HAWT above the tree line (20 meter or higher tower, 10 meters above any obstructions in area), your site is not suitable for wind power.

    You need high sustained winds (trees in area should show "flagging" from prevailing winds). And for elevation of turbine, go fly a kite. The minimum level at which the kite will be stable (no turbulence), that is the minimum height for the turbine.

    Some reading from one of our FAQ's:

    Wind Power Links
    www.otherpower.com (good forum for DIY Wind Power)
    Hugh Piggott - Scoraig Wind Electric site for tons of info (from mike90045)
    Scoraig Wind "Recipe Book" for DYI Turbines (from Chris Olson... From his 4/11/2013 post)
    www.greenpowertalk.org (added from "russ"--Like here but more wind/less solar)
    Small windpower a scam ? Survey says SO
    Truth About Skystream & SWWP
    Windmax HY-2000 2kW Wind Turbine

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • starackerstaracker Registered Users Posts: 2
    i have one of those turbines too, even when its spinning like crazy in 27 to 35mph wind, the volt meter says 0 volts, guess i got a lemon
  • BB.BB. Super Moderators Posts: 26,872 admin
    edited May 7 #10
    It could be a wiring issue... If you want, start a new discussion (thread) and we can see if there is anything that can be done.

    Note--As above--Just getting the turbine "working" does not mean that it will output a lot of current (power=voltage*current) into your battery bank because of location/installation and typical turbine design issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LumisolLumisol Registered Users Posts: 374 ✭✭✭
    There are some solar and wind PWM controllers that could do the job.
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