WS500 T-105 settings with Cerbo and MPPT

• R

  Rick OGM Support Staff

  5/19/23, 9:51 AM

  "posted for Stefano"

  How should I set the MPPT charging profile as to work well with the WS500? 

  I run a WS500, with a Victron SmartSolar MPPT, all connected to a Cerbo GX and Smart BMV712. They all charge a T-105 with 6 units, for a 3 12VDC banks. I have a few questions.

  All working file at the dock as far as i can tell.

  The WS500 is follows the T-105 profile and the parmaters are shown below

  1) What is the proper charging profile for the MPPT? Should it be exactly the same as the one specified in the WS500 config file? Or should solar somehow be subordinated to the WS500? Which one should go to float first? Right now the MPPT charging profile is set to generic preset for flooded batteries, but conisdering changing to expert. 

  2)  Left the dock for a sea trial with batteries fully charged.  All was good for a while. At one point the engine tachometer shut down, and the alternator stop charging. I turned the PV off suspecting that it may have had something to do with it and the charging voltage came back and tacho too. What is the likely cause of the stop charging. Any insight about this situation,  possible approaches to address?

  I did not have the time to extensively investigate and trouble shoot and I am trying to understand why and how to prevent in the future. 

  Is there any documentation about this type of system optimizaton?

  These are the config paramenters for the WS500.

  # Trojan Signature Line Flooded  
  $SCA: 0,85,0.90,0.75,0.50,0,0,0,10000,0,0,30,0@
  $SCT: 12,2.83,0,0,0@
  $CPA:7 14.7,240,10,0@
  $CPO:7 0,0,0.0,0@
  $CPF:7 13.5,-1,0,-10,0,12.9,50,0.0@
  $CPE:7 16.2,0,180,10@
  $CPP:7 0,0.0,0,0.0@
  $CPB:7 0.030, -9, -45, 45, 0.0, -99, -99, 0, 65@
  $SCN: 0,Trojan T-105,1234@
  $SCO:7,1.35,0.0,0@

  The main presets for the MPPT are

  Absorption 14.4V

  Float 13.8V

  Equalization 16.2

  Re-bulk voltage offset 0.4V

  Thank you very much,

  Stefano

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• R

  Rick OGM Support Staff

  5/21/23, 3:18 PM

  Q1)  The WS500 and MPPT do not share data at this time and they will both try to charge your batteries independantly so you will want to consider your circumstances.  You can configure both chargers so that either one will try to charge to 100% or for instance use your alternator to only charge to 90% and let your MPPT do the top off.  If both chargers are on the same power circuit and the wire is undersized you may have situations where the charging by one will fool the other one due to the voltage drop on the charging pwer wire.  We suggest you bring both wires, (well sized) directly to your battery main connection or closest main bus bar

   

  Q2)  It seems that your alternator output dropped right off and that is why you lost your tach.  You need to maintain a minimum field output to get the sine wave needed for the pulse counter the tach needs and you can just set up your minimum field output to do that.  Check out page 28 of the detailed programming manual and look over the SCV parameters to set it up.  The manual can be downloaded here:    

  WS500 Programming and Communicatins manual

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• S

  Stefano

  5/21/23, 6:54 PM

  Thanks Rick. This is very helpful. Apparently there are two issues. The dual source of charge and the shttign down of the field when the batteries are full. I will address the first with a manual PV breaker at the panel for the time being. 

  As for the second, i looked in the manual as you suggested.

  It looks like the SCV includes "TachMinField: Minimum % of field drive that will be applied if TACH MODE is enabled." which may help, but i would not know how to implement it in the entire line of command in the Trojan config file, and there is no example i can follow to avoid disaster.

  However, in the config there is this line that determines the overcharge behavior which for the Trojan is.

  $CPO:7 0,0,0.0,0@   (e.g. disabled)

  where the syntax is 

  $CPO:n <Limit Amps>, <Exit Duration>, <Exit VBat>, < Exit Amps >

  In the manual at pag 38 it also reads. "In another special application of OverCharge phase (available in firmware v2.4.x and above), the limit amps may be set to -1. In this case ‘Exit Vbat’ is often set to match that of the Float target voltage and the above mentioned revert to Bulk/Acceptance is not checked for. This usage of Overchage can be helpful to manage the transition from Acceptance phase to Float in cases where it is desired to keep an external tachometer active."

  In the trojoan case I wonder if modifying the $CPO command line as follows would keep the tacho on.  

  $CPO:7 -1,0,14.7,0@

  Where -1 is from the paragraph above in the manual and 14.7 is the bulk voltage set same as the voltage stated in the $CPA command line.

  Any thought? Does this look correct to you? 

  Many thanks,

  Stefano

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