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Automatic System Characterization

Once the regulator is wired, its Vessel Info is filled in, and you've set the commonly-adjusted settings for your bank and alternator, run Automatic System Characterization once. It measures how your alternator and engine actually respond and sets the control loop and over-current protection from those measurements — instead of leaving you to guess at gains and thresholds.

You launch it from System Settings → Commission Current Loop. The whole routine takes a few minutes and a short engine run.

Why it's worth doing

The regulator ships with safe, conservative defaults, but the right control-loop gains and over-current thresholds depend on your specific alternator, belt, and engine. Characterization tunes them to your installation so the regulator reacts quickly without overshooting — and so the over-current protection sits at the right level. That last point matters even when you hold a fixed voltage target, and especially on large battery banks, where the voltage barely moves as current climbs: voltage-based protection has little to react to, so a correctly-sized over-current threshold is what catches a runaway.

Before you start

  • The engine can run and the alternator is producing current.
  • The battery has charging headroom — not nearly full. Characterization has to hold a current while it measures, and a full bank won't allow that.
  • No other tuning test is running.
  • You can hold the throttle steady when asked, then sweep it once.

You never touch the field

The regulator drives the field itself throughout. Your only job is to set engine speed when the routine prompts you. Your current settings are saved before anything changes, so you can Abort at any point and everything reverts to exactly how it was.

What happens, step by step

The routine walks through a few stages. At each one it shows you what it measured and proposes — nothing is written until you click Apply.

  1. Hold a cruising speed. Bring the engine to your typical cruising RPM — the highest you normally hold — and keep it steady. The regulator maps how the alternator's output responds and proposes the control-loop gains and filter time constants. Review them and click Apply.

  2. Stability check. Still at the same speed, it runs a quick closed-loop test to confirm the new gains are stable. If they came out too aggressive it offers to soften them and re-check.

  3. Sweep the speed range. From idle, slowly and continuously raise the throttle to about 2000 RPM (or your maximum if lower) in one pass — no need to hold, just creep it up. This records the normal current fluctuation at each engine speed.

  4. Over-current thresholds. From that sweep and the earlier measurements, it proposes the over-current detector's averaging time and trip floor. Review the proposed values and click Apply.

  5. Done. Mark the device characterized. A short hold at the roughest speed the sweep found confirms the thresholds don't false-trip.

A warning badge in System Settings reminds you to run this until it's complete. You can pause partway — for example between the cruise hold and the speed sweep — and resume later; any settings you've already applied are kept.

Watching the over-current detector

During normal running, the Group 3 over-current detector shows a live chart in System Settings, under the protection settings. It plots the time-averaged amount your alternator current sits above what the regulator is commanding, against the threshold that would trip it. A clean run keeps the current trace well under the threshold line; a real over-current crosses it and draws a marker. Use it to confirm the thresholds characterization set are sitting comfortably clear of normal operation.

See Safeties & Protections for how all the protection layers work together.

If you skip it

The regulator still runs on its conservative defaults — it's safe to use as-shipped. But the control loop may be slower to settle than it needs to be, and the over-current threshold is a generic value rather than one matched to your alternator. Running characterization once is the recommended setup step after wiring and initial settings.

Cross-references