Denso 021080-0140 Alternator | 12V 150A SC Hairpin | John Deere RE186320 / RE257541

The Denso 021080-0140 (New) is a 12-volt, 150-amp internally regulated alternator from Denso's SC "Hairpin" family, serving as the OE-equivalent charging unit for John Deere agricultural tractors under John Deere numbers RE186320 and RE257541. It uses an 8-groove serpentine pulley and internal fan/regulator, cross-referencing to Lester 12660.

Key Features:

12V / 150A output — high-amperage charging for John Deere ag tractor electrical loads; internally regulated, internal fan.

Denso SC (Hairpin) design — the OE alternator family for these John Deere applications, with an 11:30 regulator clock position.

Spool mount, verified geometry — Mount Hole 1 M8x1.25 threaded, Mount Hole 2 ~10.2 mm unthreaded; mounting-ear thicknesses 22 mm (0.866 in) and 58.4 mm (2.299 in).

8-groove serpentine pulley — solid type, ~70 mm (2.756 in) OD.

Standard Denso terminals — B+ M8x1.25 stud; S, IGN, and L spade terminals; negative polarity.

OE-equivalent fit — direct replacement on listed John Deere models (RE186320 / RE257541) with no modification.

Specifications:

Part Number: 021080-0140

Brand: Denso

Component Type: Alternator (SC Hairpin family)

Condition: New

Voltage: 12V

Output: 150 A

Regulator / Fan: internal / internal

Regulator Clock: 11:30

Mount: Spool — Hole 1 M8x1.25 threaded; Hole 2 ~10.2 mm unthreaded; ear thickness 22 mm / 58.4 mm

Terminals: B+ M8x1.25; S / IGN / L spade; negative polarity

Pulley: 8-groove serpentine, solid, ~70 mm OD

Lester Reference: 12660

Compatibility:

Denso OE unit for John Deere agricultural tractors, cross-referenced to John Deere RE186320 and RE257541. Reported applications include John Deere 4720, 7720, 7815, 7820, 7920, 9120, 9220, 9320(T), 9420(T), 9520(T), 9620(T) (6068-family diesels)

Conclusion:

The Denso 021080-0140 is a 12V, 150A SC Hairpin alternator that restores OE charging output on John Deere ag tractors carrying RE186320 / RE257541. With verified spool-mount geometry, an 8-groove serpentine pulley, and standard Denso terminals, it's a direct OE-equivalent replacement for the listed applications.