# Wind turbine charge controller & voltage regulation concern

Discussion in 'The Projects Forum' started by MasDokase, Oct 15, 2016.

1. ### MasDokase Thread Starter New Member

Oct 15, 2016
1
0
Hi all
I'm afraid I'm pretty useless when it comes to electronics so I apologise if this is a stupid question. I am building a DIY wind turbine with a 12V battery bank using a 24V DC permanent magnet motor from a mobility scooter as the generator (no details on speeds, current etc as the Chinese manufacturers decided not to print that info on the motor - but I've got it putting out 15v using a 14.4v cordless drill so the speeds and voltages are within spec for my turbine).

I envisage the following 4 states but I could be wrong (questions in paragraphs below):
1. Wind generating less than 13V = no action required by electronics
2. Wind generating >13V but <20V (regulated down to 14.4V potentially?) = charge batteries if required (on at 11.9V and off at 14.4V)
3. Wind generating >13V but <24V = divert to dump load once batteries charged
4. Wind generating more than 24V = brake the windmill ---- this will be by mechanical means so does not require an electronic solution (though one would be great if it's easy enough to make)

On solar charge controllers, they will tolerate voltages up to, say, 25V for a 12V charge controller and regulate this down to a charging voltage (say 14.4V). Once the battery is charged they open the circuit. The problem with using these is that 1) wind turbines can potentially generate voltages which will fry the solar charge controllers and 2) in high winds an open circuit will result in minimal resistance on the generator allowing it to speed up to the point of being damaged.

So, I have looked at the charge controller from Michael Davis (http://www.mdpub.com/555Controller/ and attached). From what I can see this uses the 555 IC as a timer and it checks the battery voltage to determine whether to send the input either to the battery bank or to the dump load. If the power from the input is sufficient and the battery needs it, it will send the charge to the battery. But let's say the input charge is 18V which is too much for a 12V battery to handle - as I understand it, it will divert all voltage to the dump load once the generation is outside of the ideal range? So my concern is that the odds of me always running the wind turbine in the ideal charging range is pretty small and thus I would most frequently be diverting to the dump load in decent winds. Is this correct or is my understanding wrong? Will this in fact work fine to charge the batteries despite the higher voltage and only divert to the dump load once the batteries are charge. Is there a way I can add a voltage regulator to allow me to bring the voltage down from 20V or even 24V to a useful voltage for charging the batteries? What if I used a hybrid design using the 555 controller with a solar charge controller (I'm not sure how to do this but it seems plausible)? Or is this even necessary - perhaps I misunderstand the thing entirely...

This setup is not intended as anything other than an experiment so I am loathe to buy an expensive controller or one that doesn't do what I'd like it to.

Many thanks for your input.

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2. ### tcmtech Distinguished Member

Nov 4, 2013
2,684
2,446
I have played with wind power since I was in my teens which are now 25+ years ago.

Back when I used batteries, before I came up with a cheap way to build Grid Tie Inverter system just used a simple active shunt system that limited the battery voltage ~14.4 volts.

http://www.electro-tech-online.com/threads/grid-tie-inverter-schematic.86777/ and here, http://www.electro-tech-online.com/threads/grid-tie-inverter-schematic-2-0.105324/ , for starters.

Anyway, if multistage charging was needed that could be done easily enough with a modern battery charging control IC that regulates the clamping voltage of the load dump shutting systems as well.

Reason being a with a wind generator is you have a properly sized generator you can control voltage output just by loading the unit down to keep its speed under control.

Last edited: Oct 16, 2016
3. ### Colin55 Member

Aug 27, 2015
308
30
You have to give us the A-Hr of your battery. The number of days the wind blows. The hours per day, the A-Hrs removed from the battery each day and the velocity of the wind.
You can put a cowling around the blades to increase the performance 200%.