I have heard that a motorcycle battery should never be charged at more than 1/6th of its amp rating. Now, if the output of the rectifier/regulator is directly connected to the battery, then how excess current taken care of?. Is it that the output current of the rectifier/regulator is never more than the specified safe charge current of the battery?. and if the output current of the rectifier/regulator is more, then is there another component in between the output and the battery?
Please help

 

The alternator or dynamo gives out a fixed voltage for the battery, ie 12v batt usually 14v output, if the battery is flat then it takes more current to get it upto charge,once it reaches charging the current drops off,there is a current limiter in the regulator.

 

Current limiting is built into the rotor (generator) and the regulator of a motorcycle to correctly charge the battery. I does not make sense to pay thousands of dollars for a motorcycle and it not have the right charging system.

Mark

 

Magnetic saturation in the flux path from rotor to stator takes care of the current limiting... True for both wound-field and permanent magnet field alternators...

 

there are two main tyhpes of regulators used, series and shunt. the series regulator iether reguates the out put of the alternator by adjusting the rotor voltage, or using a series regulator like power supplies do. the shunt regulator bypasses excess current to ground to pervent overcharging. the simplest shunt regulator used is a zener diode across the windings, rectifies and regulates at the same time.

 

Hi All, Thanks a lot for the quick and informative replies. I gained a good knowledge of how the power is regulated. Here is why I was asking the question. (It would be too risky to experiment it without prior knowledge as it could damage my battery and maybe my RR too)
I have a battery rated at 12V and 3AH. The generic diagram of the electrical system could be as shown in attached file1.

 

I have a load (BLDC motor) ,which I need to be running at constant power (12V, 4A) for some cooling purposes. I am planning to connect this load as shown in attached file2.

 

Now, if my RR is capable of delivering 4.5A current at idle RPM (which it divides among the load and the battery charging), can I safely connect the load as shown above? If not, is there any alternate configuration I can adapt to make this work?

 

Any motorcycle alternator that I'm aware of is a 'permanent magnet rotor ' type. The regulators for that type alternator are of the 'shunt' type, getting rid of unused voltage/current as heat.

 

some bikes have wound rotors, such as the yamaha xs650. those use the regulator to provide regulation for the armature coil which is fed with brushes and slip rings. I wish my old yamaha had a magnet in the rotor, it kept failing.

 

some bikes have wound rotors, such as the yamaha xs650. those use the regulator to provide regulation for the armature coil which is fed with brushes and slip rings. I wish my old yamaha had a magnet in the rotor, it kept failing.

The whole series of Yamahas from about 1978 - 1885 (maybe later) had that problem from the XS models, the Seca (XJR), Maxim (XJ), Virago (XV), and Vision (XZ). I still think yamaha owes me about $500 for stators that I bought and had installed - I didn't own any tools or have access to repair space at the time.