wind question: what to put downstream of the alternator?

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vinzman
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wind question: what to put downstream of the alternator?




by vinzman » 20/07/12, 17:38

Hi everybody,
I want to use a modified car alternator (wind turbine) to charge a bank of 12vdc batteries wired to 24vdc.
The problem that leads me to ask my question is that my alternator produces from 0 to 77vdc and the manufacturer announces a maximum power of 500w.
I imagine that my batteries will not appreciate being charged at 77vdc and therefore, which device should I get in order to be able to have a constant voltage which allows to charge my batteries?
Thanks in advance.
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chatelot16
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by chatelot16 » 20/07/12, 20:11

if you plug your wind turbine on 24V it will never be 77V

below the speed where it is 24V it will do nothing, above it will give all the current it can to the battery and its speed will not go up, or just a little: only the current will increase

as long as the battery is not full and which is of sufficient size to accept the maximum current of the wind turbine everything is fine

when the battery is full you have to stop the wind turbine completely ... but as a battery is never completely full we can just limit the voltage by wasting the superfluous current in a regulator

as the wind is free limiting the battery voltage with something as stupid as plugging in electric heaters is not stupid

another problem arises below the speed to make 24V: with something so simple the wind turbine will not produce anything: we could put a switching power supply with the retention ratio set to seek the maximum power ... it does think about the MPPT of photovoltaics


but beware the MPPT for photovoltaic does not work for wind turbines: it is completely muddled by the inertia of the rotor: in the genre the MPPT reduces the voltage a little: it makes a nice increase in current especially because it lowers the speed and recovers kinetic energy of the rotor: happy with this increase, the MPPT lowers the tension even more until it stops completely

for me the way to optimize a wind turbine is to put a small propeller to measure the wind, and to have recorded once and for all at what speed or what tension it is necessary to make the wind turbine work according to the wind speed
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vinzman
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by vinzman » 22/07/12, 16:49

Ok then, if I understood correctly what you said to me and in my words, I just have to connect my battery bank in 24v, and my alternator will no longer be from 0 to 77vdc but rather from 0 to 24vdc.

I understood well?

Otherwise, for the rest, I got a PWM charge controller (xantrex c35) and I'm going to connect this to the electric water heater resistors in the house.
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bobono
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Wind issue




by bobono » 23/07/12, 12:29

Answer = A wind turbine without a regulator cannot charge batteries without damaging them.
A large choice of regulator is available on the internet at all prices
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