wide range DC to 13.8V DC converter

You need a buck switching regulator, which would convert available power to battery charging power at ballpark 90% efficiency.

How much power (in watts) does the turbine generate? How much current can the battery stand?

There may be a standard module available that does what you want. Vicor? It's not exactly a beginner's project to design a good, efficient, wide-range, current-limited buck switcher.

John

Switching regulator?

How much current can the turbine output? or whats its power rating?

meci.com had a bunch of DC-DC convertors....

Buck converter.

Assuming that the current/power are relatively low (otherwise the shunt resistor approach wouldn't be realistic), and you don't need particularly high efficiency (it couldn't be any worse than a shunt resistor), this isn't that hard.

You can get dedicated chips which will do most of the work (search for "switching regulator"), but at low power you could probably get away with just using an op-amp wired as an inverting comparator with some hysteresis: if the output voltage is too low, turn the switch on, if it's too high, turn it off.

Thanks for the info.

The turbine is rated at 100W, and can deliver around 8A. But I would rather over-spec anything I connect to it as in high winds it may output more.

If modules are available, I could presumably connect several in parallel to achieve the current handling?

I have thought about this problem before.

It is a complex load matching problem. The electrical load that the turbine feels will directly effect the mechanical resistance of the turbine. But for any given wind speed there is an optimal rotation speed to deliver max power. That is, as the wind speed goes up, you can ratchet up the resistance on the turbine. But if you ratchet it up to high, too soon, the turbine will enter into an inefficient aerodynamic region, and no longer deliver loads of power.

Furthermore, depending on the state of the battery, there is a max power it can accept (going down to near zero when the battery is fully charged). In case the turbine is delivering more electrical power than the battery can accept, you need to dump that power into some kind of heating device (resistor or transistor load).

If you have something that works already, and was designed by professionals, I would not try to improve on it.

--Mac

chris snipped-for-privacy@hotmail.com posted to sci.electronics.design:

Probably not, unless they were specified to do that.