also new to windpower

[Stu Perry]

Hi there. I have just constructed a wind turbine having converted a smart drive motor. I have attached a rectifier and I thought I had wired turbine to generate maximum of 48 volts. In strong winds it belts out 60 volts DC plus. Is that normal?
Next question I have is I would like advice on controllers between rectifier and batteries and any other components I need.
I'm reasonably capable but need some expert advice. Being in rural New Zealand, I may have to source components from overseas. Anyone can help me?

Cheers. Stu

[Bill von]

>In strong winds it belts out 60 volts DC plus. Is that normal?

What sort of generator are you using? Brushed DC? Brushless DC? (they are similar) Alternator? (that's very different) AC induction motor?

Given your question I am going to assume that it is brushless DC; most drive motors are. In that case the rotor magnetic field does not change, so your voltage will be directly proportional to motor speed. Most systems use a dump load to keep the battery from overcharging (and keep the speed of the rotor limited.) You will need a very specific charge controller that can do that. The old Xantrex C40 can do a dump load, and there are several newer devices (like the Midnite Classic + Clipper) that can do that as well, at a much higher efficiency.

[Rob Beckers]

Stu, 60V DC is good! It takes that much to charge a 48V battery bank (the 'absorb' Voltage for flooded lead-acid batteries is normally right around 60.0V and that is before temperature compensation, 'equalize' is actually 63V DC, so you may still be on the low side!).

The type of controller Bill mentions is a "diversion controller" that can be set up to divert excess charging of a battery bank to a dump load (resistor), to avoid overcharging the batteries. Have a look at the Morningstar TriStar series, those are commonly used and work well, you will also need a dump load resistor of the right resistance value.

The 'other' type are MPPT charge controllers and only the MidNite Classics come to mind for wind. The turbine needs to produce more than the needed battery Voltage for those to work. They can be more efficient by loading up the turbine just right, so it spins at the optimal TSR, but at the cost of complexity and additional money.

-RoB-

[Stu Perry]

Thanks guys. Bill the motor I converted to a generator is a fixed magnet 36 pole Stator motor. 6x2 coils in series
Output is three phase and through a rectifier converting to DC. -
Obviously I'm new to this and am very cautious about fiddling with electricity.
Rob, Ill look at the controllers you mention - Ive also been reading up about dump loads and various ways of building one.
I'm not in a rush to build all this. Ive built the turbine, made my own blades and it works really efficiently. I decogged the poles so it starts up with relatively light winds. Currently its sitting up on the mast Ive built - without blades until I get the equipment and circuits in place.
Cheers

[Stu Perry]

Found these on the internet through ebay. Are they any good?

https://www.ebay.com/itm/LCD-Wind-Solar-Hybrid-Charge-Controller-MPPT-Boost-Charge-12-24V-Auto-900-1200W/362604015743?hash=item546ce2307f:m:mkTdH3dfl4uVBmt eBVOU9FQ

[Rob Beckers]

Stu, you're on your own when it comes to Chinese charge controllers. Some are decent, many are total junk. Proceed with caution.

For an MPPT wind charge controller the MidNite Classic is used (usually their 200V or 250V to give some margin in case of a runaway). MPPT controllers need a higher input Voltage, they can only convert downward to the battery Voltage. I don't know what load, RPM and TSR you are seeing the 60V DC at, you probably need a bit more to effectively use an MPPT controller. The idea behind MPPT controllers is that you put a table in the controller that tells it what load to put on the wind turbine (how much current to send into the batteries) vs. the input Voltage from the turbine. You can reason this backward to TSR and blade angle-of-attack, but it works out that with the right table the turbine will always run at its most efficient in converting kinetic energy of the wind into electrical power.

If you're new at this I would stick with a simple diversion controller. Get a MorningStar TriStar (the PWM version), and a resister of the right value/Wattage. It's a much safer way to go as well, because the batteries will always keep a load on the turbine, avoiding run away.

-RoB-

[Dave Lahar]

I agree 60V is a good thing; higher of you are using a Midnight Classic MPPT, as you need a bit of headroom for the the CC to work in.

You might also check out the Back Shed forum. Those guys are all about smartdrive alternators; particularly F& P models.

Best, d