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ErrorLib — Industrial Fault Code Library

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33

Battery Overvoltage in I2 Phase

Fronius · Perfect Charging

What does 33 mean?

The battery voltage exceeded its safe limit while the charger was operating in the I2 (secondary constant current) charging phase. This indicates a problem with the charger's voltage regulation or an issue with the battery itself during this critical charging stage.

Common Causes

  • A malfunction in the charger's voltage regulation circuit specifically during the I2 phase, allowing the voltage to rise too high.
  • Battery cells becoming overcharged or experiencing premature voltage rise due to internal imbalances or defects.
  • An incorrectly configured I2 phase voltage limit in the charger's settings, set higher than the battery's safe maximum.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Disconnect the battery and measure its terminal voltage directly.

  2. 2

    Verify that the charger's I2 phase voltage limit setting (parameter, if available) accurately matches the battery's specified maximum charging voltage.

  3. 3

    Monitor the charger's output voltage and current during the I2 phase, if safely possible with diagnostic equipment, to observe regulation behavior.

Browse all codes in this manual (61)
Verified technical data. Last updated: April 2026

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Source: Fronius Perfect Charging
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