Wednesday, May 20, 2015

Improving efficiency of DC generator - alternator configuration

This post is not directly related to the DC Generator controller, but I figure it is related and relevant.

This year I have altered the alternator being used on our Kubota EA-300 based DC generator, switching out a large framed 130A alternator for an even larger framed 200A one.  Though the more interesting part is I also adjusted the drive ratio from 2.5:1 to 1:1  (More detailed here:  )

My reason for doing this is alternators loose efficiency as RPMs are increased.  By using a larger alternator, and turning it slower, I have picked up perhaps 7% in overall system efficiency.   A very nice gain.

But it occurred to me there is even better news here: The controller's active throttle control matches engine speed to the load it is being asked to drive, slowing the engine down during the last potion of the Acceptance phase of battery charging.  Guess what: This slowing down just pushes us into a more and more efficient operation range for the alternator!  Though I have not measured it, it does occur to me that during those final 'packing it in' phases which lead-acid batteries oh so like and need for proper health - we get an additional benefit of even higher overall system efficiency.

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