Version 0.1.6 of the source code has been posted under the resource tab above. There are several small changes - mostly refinements with the TACH mode of operation as well as integration with an external BMS typically used in LiFeP04 batteries. The accompanying documentation has also been updated to reflect these changes, again under the resource tab above and now release 0.1.3
Here is a summary of the changes:
- Corrected fatal coding error in withdrawn release v0.1.5 - manage_alt(); (Uninitialized variable: enteredMills)
- Corrected ASCII error in CPE; string, not reporting float_to_float values correctly.
- Improved feature_in() handling to retain last know state while checking for debouncing.
- Much improved Tach mode code
- Setting tach PWM via $CST: command will become effective immediately, even during engine warm-up hold off period.
- Tach mode will hold min PWM during transition into Float, allowing tach to continue to run when initially entering float mode.
- Reduced MAX_TACH_PWM from 100 to 75, to better protect battery from too high a PWM floor.
- Added new Amp-Ah based exit criteria for Float and Post-float
- Added Alternator state: FORCED_FLOAT mode - enabled by feature-in port with CPE#8 for use with external BMS system
- AST; modes mode numbers updated to include new alternator mode FORCED_FLOAT
- Changed SST; status to include version number as opposed to compile date/time.
- Increased NTC usable temperature range, now reporting -54f to 300f
- Shortened engine warm-up hold off period from 60 seconds to 30 seconds
- Dash lamp now illuminated during engine warm-up hold off period, to emulate typical 'lamp test' behavior during startup
Many of these refinements came about through the hard work of Antti-Pekka Virjonen who has deployed the Smart Alternator Regulator with a nice new LiFeYPO4 battery in conjunction with a BMS. I really appreciate the feedback from others, and the help of Antti-Pekka in helping me. We not only made several improvements to the tach mode of operation, but also refined the function of the feature-in port when used in conjunction with an external BMS.
And I am glad to report the PID tuning worked spot-on with his system! No changes needed at all! I can see where perhaps adding in a little 'I' might tighten regulation up some, but as is the system held target voltage with 25mV of the goal during trial runs.
Please make sure to download both the new documentation as well as the source and note the few changes in status strings (SST and AST).
Thank you again A-P, and happy sailing this summer!
And be on the look out for hidden resistors. One person found a large 270 ohm 5W resistor attached from the old D+ terminal (no longer used) to GND. Originally intended to help drive the dash lamp and also provide a minimum load to keep the alternator driven tach running, this extra phantom load played havoc with the Smart Alternator Regulators attempt to stabilize things with its own tachometer mode turned on.