15-Amp Voltage Regulator Rectifier for Kohler 8-25 HP Engines

Precision Voltage Regulation: Maintains a steady charging voltage (typically between 13.8V and 14.5V) to the battery, preventing overcharging and protecting sensitive electronic components.
Efficient AC-to-DC Conversion: High-quality internal diodes convert the alternating current (AC) from the engine's stator into the direct current (DC) required by the battery and ignition system.
Heat-Dissipating Aluminum Housing: Designed with an integrated finned heat sink to rapidly dissipate the heat generated during the rectification process, extending the component's lifespan.
Universal 3-Terminal Configuration: Features a standard "AC-B+-AC" layout, making it a drop-in replacement for standard 15-amp charging systems on large V-twin engines.
Sealed Internal Circuitry: The internal electronics are potted in a high-grade epoxy to protect against vibration, moisture, and engine debris.

Kohler: 41 403 10-S, 41 403 09-S, 25 403 03-S, 25 403 20-S, 25 403 29-S, 25 403 39-S
John Deere: AM102596, AM34738

This regulator is designed for Kohler Command and Magnum series engines equipped with a 15-amp charging system. Key compatible models include:

Kohler Engines: Fits CH18, CH20, CH22, CH23, CH25, CV18, CV20, CV22, CV25 series (8 HP through 25 HP).
Equipment Types: Commonly found on John Deere lawn tractors, Grasshopper mowers, and various zero-turn mowers, skid steers, and portable generators.
Note: Not compatible with 20-amp or 25-amp systems which typically utilize a different plug configuration or higher capacity heat sinks.

Battery Not Charging: The battery consistently dies after use, and a voltmeter shows less than 13V at the battery terminals while the engine is running at full throttle.
Overcharging (Boiling) Battery: The battery casing feels excessively hot, or you notice a "rotten egg" smell (sulfuric acid), indicating the regulator is allowing more than 15V to reach the battery.
Blown Light Bulbs: Frequent failure of headlights or indicator bulbs due to uncontrolled voltage spikes.
Visible Damage: The back of the regulator shows signs of melting, "burn" marks, or the potting material has cracked and leaked out.

The Ground is Critical: The regulator grounds through its mounting bolts. Ensure the mounting surface on the engine shroud is clean and free of rust or paint. A poor ground is the #1 cause of "new" regulator failure.
Terminal Identification: The two outer terminals (marked AC) connect to the stator wires. The center terminal (marked B+) connects to the battery positive circuit.
Stator Test: Before installing, test your stator with a multimeter set to AC volts. With the engine at high RPM, you should see 28–40V AC across the two stator wires. If the stator output is low, the new regulator will not charge.
Check the Connector: Inspect the plastic plug for melted plastic or corroded terminals. If the connector is loose, it will create resistance and burn out the new regulator quickly.
Thermal Paste: While not always required, applying a thin layer of thermal grease to the back of the regulator before mounting can further improve heat transfer to the engine shroud.

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