7.3L vs 6.0L

The 7.3L Power Stroke ran from 1999 to 2003 and the 6.0L took over from 2003 to 2007, with an overlap year where both were sold. The 2003 Excursion and Super Duty could have either. Confirm which engine your truck has rather than going by model year, since the alternator differs.

Why Power Stroke trucks need the capacity

These trucks use glow plugs and run dual batteries from the factory to handle the cold-start draw. The factory alternator is sized for that and little more. Add a plow, an inverter, a winch, auxiliary lighting or an audio system and the charging system runs short.

Mechman builds direct-fit Elite Series alternators for both engines from 370 amps up to 400 amps, in cast and billet with anodized finish options.

Choosing a battery

Super Duty trucks use dual Group 65 batteries. The XS Power D6500 is a direct-fit AGM replacement. Replace both at once and match them — a new battery paired with a tired one gets dragged down to the weaker one's condition.

AGM copes with diesel vibration and the deep cycling of auxiliary loads far better than a standard flooded starting battery.

Don't skip the wiring

Dual batteries mean longer runs and more connections, each dropping voltage under load. On a truck of this age the factory cable is likely degraded as well as undersized. See our Big 3 wiring upgrade guide and Big 3 kits.

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