In my bicycle, I have a hub generator which provides alternated current, at nominal 6V / 3W.
I have built a regulator/filter/rectifier, using a rectifier bridge, a 6800 uF electrolytic capacitor, and a 6V/5W zener diode, and it is working great.
Now I am considering, as commonly seen in vehicles, to add a battery in the system, but I wonder how should a battery be wired / specified so that:
- The battery doesn't discharge through the regulator;
- Every excess power produced by the system while in use is sent to the batteries;
- Running devices take the power from the battery automatically when the generator is not running (that would mean the devices would "blindly" use the energy from the system, disregarding if it is provided online by the generator, or drained from the battery).
I guess this is a fairly simple and common setup, but I am looking for the theory involved, instead of just taking a ready circuit design for a random blog, without even knowing what I am doing.
EDIT for more context:
I am using a 6V regulated generator, so I am thinking about using 4 x 1.2V (4.8V total) rechargeables. That would be enough to keep my stuff (led lights mostly) running while the generator is not active. All the lights have series resistors, so their brightness is not severely affected by 1,2 voltage drop.
One concern is that, besides not discharging the battery through the generator (I don't think that would happen since there is a rectivier bridge there), I shouldn't damage the batteries through over-charging them if I keep riding for hours and hours...