As long as your battery bank is large enough, which it is normally from the stand by capacity point alone, you can dump all that the windmill can produce into the battery during the bulk charge phase. If you had a large windmill and a small battery you would need a current limit, but normally the battery is large enough to take all that is available.
As the battery charges you reach a point where the voltage will start to rise rapidly with current and this is where your dump load comes into effect. It clamps the voltage to a set value so the battery still takes what it needs to continue charging and the rest of the current is diverted to the dump load.
The final part of the charge cycle takes a fair while, you can't rush it, the battery just won't accept a rapid charge during the final phase.
I don't know exactly how many amps you can put into a battery in a low state of charge but 30 to 40A seems to be ok for a 100AH battery and you normally need more capacity than that for a reasonable storage.
I just use shunt regulators that divert excess charge into resistors as the voltage rises, I think this is common practice, the exact method of operation of various controllers differs, some switch a resistor large enough to dump all available power in at one voltage and switch it off again as a slightly lower voltage, others do it in several steps with a few hundred millivolts between them and others use PWM to alter the ratio of on to off and this has much the same effect as a variable resistor that keeps the voltage constant. Some do this at a few hundred Hz and the dumped current consists of a series of current pulses of differing length. Others chop at a much higher frequency and use a flywheel diode and an inductor to maintain a smooth dc current of the right value to keep the voltage constant.
I build my own but any form of controller designed for wind use will be ok. Don't use a solar controller that open circuits the charging circuit, this is fine for solar but windmills can reach high voltages and speeds and must never be open circuited.
I hope this helps you, chargers designed to charge a battery from the mains can use the 3 stage ideal charge cycle but when you are charging and taking load together you have to use the power when you have it.
As long as you do not let the batteries discharge to far or let the voltage rise much above 14 v there is not a lot more you can do.
At most don't discharge more than 80% and preferably not more than 50% unless you have some back up charger in case of low batteries and no wind.
In remote places I believe they use a large windmill to charge a lot of small batteries for members of the community and they are discharged elsewhwre.
In that case each battery could be charged under near ideal conditions with suitable chargers as long as there was sufficient wind, but that is a special case.
Flux
