Sunday, March 17, 2013

Data from 30 minute run

Today I did a 30 minute run using the latest firmware and am rather happy with it.  So much so that I 'clipped' the local jumper on the controller that allowed it to power-on w/o the remote attached.  Next week the custom remote panel will arrive and I plan to install the remote and start using this thing!  (We leave dock in two weeks and likely will need the generator for a couple of months until the Solar start to kick in)

And here is a graph from today's run:

30 minute sample run.
Note that VBat values are plotted against the left scale and are shown 10x their true reading.
(Battery voltage ranged from 13.5v to 15v, not 135 to 150v!)

You can see a full start, ramp, bulk, acceptance phase charge cycle here.  I manually stopped the generator while still in Acceptance, as I typically do not let it run after getting down to 40A or so.  No reason to listen to the noise for only 40A's...

A few things to point out:

  • You can see early on the starter engaging:  VBat dipped, and Amps went negative.
  • What you can not see is the RPMs slowly increasing during warm-up period.  (See prior  Blog entry).
  • The management of Volts and Amps worked great during Bulk charge mode.  
  • Around the 9.3 minute time I turned off a large load that had been on the inverters (750w space heater).  You can see the resulting voltage rise and the controller nicely handling the situation.
  • At about 17.7 the battery voltage has climbed to its temperature compensated charging point, and the controller enters Acceptance phase - here the voltage is held constant and the Amps decline as a result of the battery's ability to accept a charge.
  • Also at this time throttle control kicks-in; the engine is slowed down in response to the lower loads.
  • And here there is still a bit of hunting as shown by the squiggly lines. It looks to be an interaction between the throttle control and alternator regulation.  Will continue to work on this.
  • And you can almost see the cool-down period where the RPMs drop slowly, until 1100RPMs (configurable) are reached when the engine is stops. 
I am very pleased with this run, it is doing all I wanted and more.  Over the next couple of months we will be using the generator a lot and I will be able to continue my monitoring.  I am also looking forward to getting the EGT installed and looking at the relationship between EGT and Load.  It is my intention to use EGT to finally decide appropriate loads on the engine (as opposed to looking for black exhaust as an indication of overloading).

On those squiggly lines, I will continue to work and see if I can desensitize the system some more to reduce hunting.  But I am also thinking over the summer I will work to upgrade the controller firmware to a proper PID algorithm.   (See PID).  And with that will  move from High School Algebra into Freshman Calculus.   See, my Math Teachers were right:  I will find a use for this stuff in the real world!

But for now, things look good.  Am going to post the Firmware after I review the detail data from today's run.  And start getting ready for a summer of cursing.

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