Briggs & Stratton Typical Tri-Circuit Alternator Service Manual

Alternator Identification

Briggs & Stratton engines are equipped with a number of different alternator systems to meet the requirements of equipment manufacturers. For example, a large lawn tractor with accessories may require a 16 amp regulated system, whereas a snow thrower with a single headlight requires an AC Only system. Knowing the type of alternator system an engine is equipped with is important, particularly when an engine is being replaced.

Briggs & Stratton alternator systems are easily identified by the color of the stator output wire(s) and the connector.

AC Only

ONE BLACK LEAD

FROM ENGINE

(STATOR)

TO EQUIPMENT

HARNESS

· 14 Volts AC for lighting circuit.

· One black lead from stator.

· White connector output lead.

WHITE CONNECTOR

OUTPUT LEAD

Stator Output Wire(s)

And Connector

(typical)

DC Only

ONE RED LEAD

FROM ENGINE

RED

CONNECTOR

TO EQUIPMENT

HARNESS

· 3ampDCunregulatedforchargingbattery.

· One red lead from stator.

· Diode encased at connector.

· Red connector output lead.

(STATOR )

DIODE

RED AND BLACK

LEADS FROM ENGINE

(STATOR)

Dual Circuit

RED LEAD

DC OUTPUT

BLACK LEAD AC OUTPUT

TO EQUIPMENT

HARNESS

10 or 16 amp Regulated

RED CONNECTOR

OUTPUT LEAD

DC CHARGING CIRCUIT

RED LEAD

WHITE

TO EQUIPMENT

HARNESS

WHITE LEAD

AC FOR LIGHTS

CONNECTOR

· 3 amp DC unregulated for charging battery (ONE red lead from stator).

· 14 Volts AC for lighting circuit (ONE black lead from stator).

· Diode encased at connector.

· White connector with two pin terminals.

Tri-Circuit

ONE BLACK LEAD

FROM ENGINE

TO EQUIPMENT

HARNESS

TO BATTERY AND CLUTCH CIRCUIT

5 AMPS DC (-)

TO LIGHTS

WHITE LEAD

RED LEAD 5 AMPS DC (+)

TWO DIODES ENCASED

IN WIRE HARNESS

(STATOR)

GREEN

CONNECTOR

· 10 amp AC.

· One black lead from stator.

· Green connector.

· Two diodes encased in wire harness.

· Red and white output leads.

ONE BLACK LEAD

FROM ENGINE

(STATOR)

5 or 9 amp Regulated

RED

CONNECTOR

EQUIPMENT

HARNESS

TWO BLACK LEADS

FROM ENGINE

(STATOR)

YELLOW

CONNECTOR

REGULATOR

RECTIFIER

ONE RED

LEAD

TWO YELLOW LEADS

· 10 or 16 amp DC regulated for charging battery.

· Alternatoroutputisdeterminedbytheflywheel alternator magnet size.

· 10 and 16 amp system use the same stator, color coding and regulator-rectifier.

· Two black leads from stator.

· Yellow connector with two pin terminals.

· Two yellow leads to regulator-rectifier.

· One red lead from regulator-rectifier to red

connector output lead.

493219 Regulator/Rectifier

Used With Charge Indicator Circuit

TO EQUIPMENT

HARNESS

WHITE

CONNECTOR

RED WIRE AND RAISED

RIB INDICATES DC OUTPUT

BLUE WIRE

CHARGING INDICATOR

GREEN

CONNECTOR

YELLOW

WIRE

REGULATOR

RECTIFIER

· 5 or 9 amp DC regulated for charging battery.

· Alternator output (5 or 9 amp) is determinedby

flywheel alternator magnet size.

· Uses same stator as Tri-Circuit system.

· One black lead from stator.

· Green connector.

TWO YELLOW

493219 REGULATOR

RECTIFIER

LEADS

· Uses same stator as 10 and 16 amp system.

· DC output the same as 10 or 16 amp system.

· Charge indicator light andwiring supplied by

equipment manufacturer.

· Red DC output wire to white connector.

· Blue charge indicator wire to white connector.

YELLOW

CONNECTOR

Engine/Alternator Replacement Information

With the exception of the AC Only alternator, all of the alternator systems referred to in this book have a battery as part of the electrical system.

There are specialized applications that use an alternator without a battery. An example would be certain generators or welders that use alternator output to excite an electrical field. For the equipment to function, the alternator output must be very evenly matched to the equipment requirements. When replacing an engine in these applications, the alternator must be the same as the original.

Replacing Briggs & Stratton Engines

When replacing an older Briggs & Stratton engine on a piece of equipment with a newer Briggs & Stratton engine, sometimes the newer engine has an alternator system different from the alternator system on the original engine. This means that the output connector on the replacement engine is not compatible with the original wiring harness on the piece of equipment. For example, the original engine may have been equipped with a Dual Circuit system and the replacement engine is equipped with a regulated system. We can integrate the two systems by making an adapter harness from readily available parts.

Generally an unregulated DC system (DC Only, Dual Circuit) should not be used to replace a regulated system because alternator output may not be sufficient for equipment requirements. However, because the equipment requirements are usually much less on an unregulated DC system, a regulated system may be used as a replacement. The regulator/rectifier prevents the battery from being over charged.

NOTE: The AC Only, DC Only, Dual Circuit, Tri-Circuit as well as the 5 and 10 amp regulated systems use flywheels with small alternator magnets. The 9 and 16 amp regulated systems use flywheels with the large alternator magnets. See figure below for magnet sizes.

*Small Magnet 7/8” x 11/16”

ALTERNATOR

MAGNETS

*Large Magnet 1-1/16” x 15/16”

(22mm x 18mm)

(27mm x 24mm)

* V Twin Alternator Magnet Size: Small 7/8” x 21/32” (22 mm x 17 mm)

Large 7/8” x 29/32” (22 mm x 23 mm)

The following are alternator replacement combinations which require an adapter harness. All of the necessary components are shown.

1. Original engine equipped with AC Only alternator. Replacement engine equipped with Dual Circuit alternator.

Modify 393362 harness supplied with replacement engine by removing red DC wire. Then, splice 393537 connector into white AC wire and connect to equipment harness.

EQUIPMENT

HARNESS

DUAL CIRCUIT CONNECTOR

(FROM ENGINE)

BLACK

RED

RIB

393362

HARNESS

RIB

AC WIRE

(WHITE)

SPLICE

393537

CONNECTOR

(GREEN)

2. Original engine equipped with DC Only alternator. Replacement engine equipped with Dual Circuit alternator.

Modify 393362 harness supplied with replacement engine by removing white AC wire. Then, splice 393537 connector into red DC wire and connect to equipment harness.

DUAL CIRCUIT CONNECTOR

(FROM ENGINE)

BLACK

RED

RIB

393362

HARNESS

RIB

DC WIRE

(RED)

SPLICE

393537

CONNECTOR

(GREEN)

EQUIPMENT

HARNESS

3. Original engine equipped with Dual Circuit alternator. Replacement engine equipped with 5, 9, 10 or 16 amp regulated system.

Modify 393422 harness supplied with replacement engine by splicing in 399916 connector assembly. Connect to equipment harness.

399916 CONNECTOR

OUTPUT CONNECTOR

FROM REGULATOR

ASSEMBLY

SPLICE

EQUIPMENT

HARNESS

393422

HARNESS

RIB

4. Original engine equipped with Tri-Circuit alternator. Replacement engine equipped with 5, 9, 10 or 16 amp regulated system.

Modify 393422 harness supplied with replacement engine by splicing into charging circuit wire and lighting circuit wire in equipment harness. NOTE: THE DIODES MUST BE REMOVED FROM THE EQUIPMENT HARNESS.

Diodes Must Be Removed From Equipment Harness

OUTPUT CONNECTOR

FROM REGULATOR

SPLICE

LIGHTING CIRCUIT WIRE

393422

HARNESS

EQUIPMENT

HARNESS

CHARGING CIRCUIT WIRE

5. Original engine equipped with Dual Circuit alternator. Replacement engine equipped Tri-Circuit alternator.

Discard 392606 diode harness supplied with new engine. Install 491546 regulator/rectifier. Add 393422 harness and modify by splicing in 399916 connector assembly. Connect to equipment harness.

399916 CONNECTOR

OUTPUT CONNECTOR

FROM ALTERNATOR

SPLICE

ASSEMBLY

RIB

EQUIPMENT

HARNESS

491546

REGULATOR/RECTIFIER

393422

HARNESS

RIB

6. Original engine equipped with 5 amp regulated system. Replacement engine equipped with Tri-Circuit alternator.

Discard 392606 diode harness supplied with new engine. Transfer 491546 regulator/rectifier from original engine. Connect to equipment harness.

The following alternator replacement combinations require no modifications.

7. Original engine equipped with DC Only alternator. Replacement engine equipped with 5, 9, 10 or 16 amp regulated system. Direct Replacement. Connect to equipment harness.

8. Original engine equipped with 5 amp regulated system. Replacement engine equipped with 9, 10 or 16 amp regulated system. Direct Replacement. Connect to equipment harness.

9. Original engine equipped with 9 amp regulated system. Replacement engine equipped with 10 or 16 amp regulated system. Direct Replacement. Connect to equipment harness.

10. Original engine equipped with 10 amp regulated system. Replacement engine equipped with 9 or 16 amp regulated system. Direct Replacement. Connect to equipment harness.

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