# Wind Turbine Charge Controller

#### labhelp

Joined Jan 28, 2010
28
I have a small turbine which is connected to a battery bank and a load. I am looking to add a simple charge controller to charge the battery until full, supply the load, and divert the power to a dump if needed. Most of all I want this to be a simple circuit that can hopefully be implemented on a breadboard. Have an of you done this before or have any ideas?

Also, I have the system relaying information to labview so one possibility that I thought of is to have labview make the decision and control the power flow.

#### SgtWookie

Joined Jul 17, 2007
22,230
Define turbine; is it a wind turbine, water turbine, jet turbine?

Does it output a relatively constant voltage/current?
What is the minimum and maximum voltages and currents?

How many batteries in your bank, what is their individual AH rating, and what voltage is the bank wired up to be?

#### labhelp

Joined Jan 28, 2010
28
Sorry about leaving out that information. It is a wind turbine. I have two 12 Volt batteries connected in series in my bank so there is a total battery voltage of 24V. The wind turbine outputs a relatively constant current. The turbine has a max of 400W so max current is around 16.5 A. This turbine is going to be mainly used for educational purposes so it is connected to a 300W load consisting of two 150W light bulbs. There is also pug ins to increase the load size.

#### wmodavis

Joined Oct 23, 2010
739
How can the output current be relatively constant. Doesn't it vary with wind speed?

#### thatoneguy

Joined Feb 19, 2009
6,359
For home small energy projects, I suggest commercial charge control units. They take a good deal into account, can balance multiple batteries, and have protection against fire.

At your power outputs, they can usually be purchased cheaper than built.

#### wayneh

Joined Sep 9, 2010
17,475
...I want this to be a simple circuit that can hopefully be implemented on a breadboard.
You're amperage is too high for a breadboard. You could have low current, control circuitry on a breadboard but you'll need to route the power circuits off-board.

I agree that on the make-or-buy scale of things, it'd be easier to just buy what you need.

#### wmodavis

Joined Oct 23, 2010
739
Some wind turbines such as the Southwest Windpower Air Breeze or Air-X 400 watt units have an adjustable charging regulation circuit built in the turbine. The manual states

"As the AIR wind turbine produces power and the battery voltage rises to the regulation set point voltage, the AIR wind turbine will go into "regulation." At that point it stops producing power and the blade rpm will lower dramatically (almost stopping). The AIR wind turbine will remain in regulation until the battery voltage drops slightly below the regulation set point – this is often referred to as the cut-in voltage. When the cut-in voltage is reached, the blades will resume spinning in response to the available wind."

http://windenergy.com/sites/all/files/3-CMLT-1333_REV_A_Air_Breeze_Manual_0.pdf

A company CirKits http://www.cirkits.com/ has a solar charge controller kit that may help you with some ideas. It is rated at 20 Amps. Though it is specified as a PV charge controller I have used it on the Air-X with good success.

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#### labhelp

Joined Jan 28, 2010
28
Thanks for the input everyone. Sorry forr the misunderstanding wmodavis, I meant that output curent is relatively constant at a constant wind speed.

I am working on this for a school project so that is why I would rather create the circuitry than purchase somehing already put together. I have done a lot of searching on the web and have found some complicated circuits that act as charge controllers but I was looking for something a bit more simple and was wondering if any of you had any ideas.

#### labhelp

Joined Jan 28, 2010
28
Some wind turbines such as the Southwest Windpower Air Breeze or Air-X 400 watt units have an adjustable charging regulation circuit built in the turbine. The manual states

"As the AIR wind turbine produces power and the battery voltage rises to the regulation set point voltage, the AIR wind turbine will go into "regulation." At that point it stops producing power and the blade rpm will lower dramatically (almost stopping). The AIR wind turbine will remain in regulation until the battery voltage drops slightly below the regulation set point  this is often referred to as the cut-in voltage. When the cut-in voltage is reached, the blades will resume spinning in response to the available wind."

http://windenergy.com/sites/all/files/3-CMLT-1333_REV_A_Air_Breeze_Manual_0.pdf

A company CirKits http://www.cirkits.com/ has a solar charge controller kit that may help you with some ideas. It is rated at 20 Amps. Though it is specified as a PV charge controller I have used it on the Air-X with good success.

As far as the solar charge kit goes, from what I have learned is that there needs to be modifications done to this circuit when connecting to a wind turbine because the solar chare contrroller is set to short the inputs when the batteries are full and if this happened with a wind turbine the output current would spike and cause damage to the system.

The problem with the internal adjustable charging circuit is that when the battery bank is full I don't wan th turbine to stop outputing, I want it to ouput to a load (two lightbulbs) if the are on. If they are off I would have to add a dump to handle the excess power.

#### wmodavis

Joined Oct 23, 2010
739
Can you tell me what wind turbine you are working with? And I appologize in that I stated wrongly that I used the charge controller with the turbine. Actually it was the Solar Power Center kit. I only used part of the circuit to disconnect the load from the battery to prevent over discharging the battery. I relied on the regulator in the Air-X to prevent overcharging the battery. The charge controller in the circuit I used does not short the input when the batteries are full, rather it disconnects the PV panel input from the battery to prevent over charging. That is preferred with solar panel but if open the circuit from a turbine it will likely damage the turbine if there is a high wind and no load to limit the prop speed.

#### thatoneguy

Joined Feb 19, 2009
6,359
The problem with the internal adjustable charging circuit is that when the battery bank is full I don't wan th turbine to stop outputing, I want it to ouput to a load (two lightbulbs) if the are on. If they are off I would have to add a dump to handle the excess power.
Often they simply turn the power into heat. Through BIG resistors, think "Pringles Potato Chip Can" size, with fins, and more than one. They send excess to a dump load, which is good in winter, but counteracts A/C or natural cooling in the summer.

#### wayneh

Joined Sep 9, 2010
17,475
Is there really a need to "dump" power? I mean, the you could just let the turbine spin without putting a load on it. Maybe the term "dump" has just become a term for any excess power beyond what the charging system needs.

Aren't we really looking to use any and all available power in some clever way? I'd say lighting is the way to go, since incandescent bulbs are designed to handle heat and you get great visual feedback in addition to free heat. It wouldn't be too tough to build a "bargraph" type load that could light up an increasing number of bulbs as the excess power level increases with wind. And then it could ratchet back to keep a reasonable load on the turbine as the wind slows.

Are your batteries lead-acid? The simplest charge controller is a constant voltage controller, for instance built around the LM317. It'll take your batteries to full charge and then cut current to a trickle. It's not ideal, but easy to DIY. Constant voltage is less ideal of a strategy with other battery chemistries.

#### thatoneguy

Joined Feb 19, 2009
6,359
Is there really a need to "dump" power? I mean, the you could just let the turbine spin without putting a load on it. Maybe the term "dump" has just become a term for any excess power beyond what the charging system needs.

Aren't we really looking to use any and all available power in some clever way? I'd say lighting is the way to go, since incandescent bulbs are designed to handle heat and you get great visual feedback in addition to free heat. It wouldn't be too tough to build a "bargraph" type load that could light up an increasing number of bulbs as the excess power level increases with wind. And then it could ratchet back to keep a reasonable load on the turbine as the wind slows.

Are your batteries lead-acid? The simplest charge controller is a constant voltage controller, for instance built around the LM317. It'll take your batteries to full charge and then cut current to a trickle. It's not ideal, but easy to DIY. Constant voltage is less ideal of a strategy with other battery chemistries.
The resistors are used when there is a lot of wind, enough to have the batteries charged, and run everything hooked up to it, and then extra. The resistors are used a "braking load" to keep the turbine from spinning too fast.

#### labhelp

Joined Jan 28, 2010
28
Is there really a need to "dump" power? I mean, the you could just let the turbine spin without putting a load on it. Maybe the term "dump" has just become a term for any excess power beyond what the charging system needs.

Aren't we really looking to use any and all available power in some clever way? I'd say lighting is the way to go, since incandescent bulbs are designed to handle heat and you get great visual feedback in addition to free heat. It wouldn't be too tough to build a "bargraph" type load that could light up an increasing number of bulbs as the excess power level increases with wind. And then it could ratchet back to keep a reasonable load on the turbine as the wind slows.

Are your batteries lead-acid? The simplest charge controller is a constant voltage controller, for instance built around the LM317. It'll take your batteries to full charge and then cut current to a trickle. It's not ideal, but easy to DIY. Constant voltage is less ideal of a strategy with other battery chemistries.
Battery is a typical battery like for a boat motor. I'm not sure the exact model off the top of my head. The LM317 is intriguing to me. Do you have any documents on how they are used and/or example circuits?

#### wayneh

Joined Sep 9, 2010
17,475
Just Google the datasheet and start there. You'll find a number of application circuits. You'll want to find one that uses transistors for higher current, since one LM317 by itself can only handle an amp or two at most.

#### labhelp

Joined Jan 28, 2010
28
One problem I am running into a lot online is that most charge controllers only allow for:
1. Charging the battery
2. Diverting to a dump

I want the added feature of if the battery is full, divert power that is coming from the turbine to the load (3 light bulbs) if they are turned on otherwise divert power to the load

#### wayneh

Joined Sep 9, 2010
17,475
Please clarify. Sorry if I've missed this. I understand that you have 3 loads; the battery, some light bulbs, and something else?

You want to supply turbine power to these with a priority scheme, something like the load first, battery charging second, and the light bulb dump third?

#### labhelp

Joined Jan 28, 2010
28
Close, I have a load which is my lightbulbs and I am planning on adding a dump.

I want to supply power to the battery first, if the battery is fully charged I want the power going to the load

#### wayneh

Joined Sep 9, 2010
17,475
OK, so the priority is battery until charged, then lightbulb load if turned on, and then dump any power in excess of charging or lightbulb.

Would you expect the load to not function unless the battery is charged? The "usual" arrangement is to give the user what he wants - power at the load - as often as possible.