Alternator Ripple on J1939: Why SPN 3644 Phantom Derate Appears Only at 1,400 RPM
At 1,398 RPM, SPN 3644 read 0%. At 1,402 RPM, it read 42%. At 1,455 RPM, it returned to 0%. The vehicle was a 2021 class-8 tractor with a 12.4 L diesel, a 28V 150A brushless alternator, a 2.5:1 pulley, and a 4.2 m charge cable that ran parallel to the J1939 backbone for 1.1 […]