I have just acquired a small treadmill dc motor and I have an old car battery. ` I'm looking to set up a small wind turbine or hydro turbine to charge the battery, but I'm getting stuck on the charge controller. From my understanding, the dc from the turbine goes into some electrical thingy "charge controller" which then dumps the load? or charges the battery?

Then the output from the battery goes into a 12v DC inverter ( I'm thinking one of those cheap things that plug into a lighter socket in a car for now) SO I suppose the question here is which cheap, charge controller do I need? Do I need one at all?
I'm looking for cheap and easiest possible I'm not looking to power my house just screw around in my shed :D

closed as off-topic by mmathis, Daniel Griscom, ThreePhaseEel, manassehkatz, Retired Master Electrician Mar 4 at 13:24

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  • Hello, and welcome to Home Improvement. Unfortunately, this isn't really on-topic here, and it too broad a question to boot. – Daniel Griscom Mar 3 at 13:49
  • Size of rotor and what profile for your blades? – Solar Mike Mar 3 at 18:32
  • Haven't decided yet, I may hook it up to a pelton wheel and not a wind turbine... – vimes1984 Mar 3 at 20:19

The charge controller is the magic part

Its job is to ensure the battery is not overcharged. It takes input from the windmill and regulates it to the correct voltage to 3-stage charge the battery.

You do not need an MPPT controller for a windmill.

You have to look at the documentation for your charge controller as to where to put the Loads.

Also, some charge controllers have a "dump" feature which can be used for excess power that cannot be put to good use (e.g. battery is full, load is low). Sending this to a bank of heaters could help assure a load on the windmill at all times).

Inverters are trouble

Inverters take energy themselves. What's more, they take energy all the times they are "on". They are a 24x7 "vampire load", and when designing an off-grid system, vampire loads are your enemy. Vampire loads suck down your battery 24x7 and force you to use larger batteries and larger wind/solar to keep them up.

Back in the day, the energy loss of inverters was more obvious, because it was a motor-generator that was physically rotating at all times. The electronic version is just quieter.

So you want to make every load you possibly can into a 12V load, so you don't need to have an inverter "spun up" in order to power it. Look for 12V lighting or cordless tools that can charge off 12V.

Watch the voltage drop

Assuming you have any distance from windmill to charge controller, you want to make the voltage as high as the charge controller can possibly manage. Otherwise you will have serious transmission losses.

  • Thank you so much for explaining this in plain English, Any recommendations on a cheap charge controller? with a dump, I'm debating whether to run the motor from wind or water... – vimes1984 Mar 3 at 14:54

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