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.
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.
