small engine charging system

   / small engine charging system #1  

musselmark

Silver Member
Joined
Aug 8, 2012
Messages
136
Location
grand tracadie PE
Tractor
'05 NH TN75DA
I have a 6.5hp electric start clone and added a second charging coil so there are 2 under the flywheel now. This engine came with a small diode and the coil I took from a honda 9hp had a small rectifier. Should I keep both independent of each other and then splice them together after their diode/rectifier or could I splice the 2 coils (ac voltage) together and then run them both through the honda rectifier and leave the tiny diode out of the picture.
 
   / small engine charging system #2  
In general, don't splice AC together. It's a waveform, and you get the sum of two waves, which is probably NOT what you want.

However if you rectify each to DC, and if its same voltage then you can splice DC keeping polarity the same.
 
   / small engine charging system
  • Thread Starter
#3  
Does a diode and a rectifier do the same thing? Why would the clone use a diode? Is it simply less expensive? If so why would honda use a rectifier?
 
   / small engine charging system #4  
Sort of. A diode would simply discard the negative part of the waveform and you would get only half the power available. Called half wave rectified.

A rectifier is an arrangement of diodes that, instead of discarding the negative lump of the alternating current, it flips the negative lump over, to above the zero line. So instead of AC which is one positive lump followed by a negative lump (alternating), you now get two positive lumps. Which is a form of DC, a lumpy DC. A better rectifier might simply have more current capacity, or could have additional components that smooth it out more. The battery will smooth it out some too, a lot - if its not fully charged yet thus has the capacity to accept all of the power that it gets.

Here's a pic from Wikipedia of alternating current (sine wave); half wave rectified, and full wave rectified.

Rectified_waves.png

One way to get some understanding is to think of your flywheel/coil unit like a 2-piston hydraulic pump (one piston up, one piston down). Flow is amps, pressure is volts. Diodes are check valves. A rectifier would be the arrangement of check-valves that you would need to make ALL of the oil flow in one direction, without wasting any flow. You would need other components to get smooth flow but hydraulic pumps are not as crude as this '2-piston' analogy.

You can think of that 2nd coil you added like another pair of crankshaft arms (& pistons), a few degrees off angle from the original.

I can't offer much more, this is appx the limit of my understanding. :D
 
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