2. Get a better alternator.

The stock alternator is truly undersized for the application as it puts out only 65 amps at hot idle and 100 amps when driving down the road at full operating temperature. It's the same part number used in the Ford Fusion! Further complicating things is the 230 amp draw caused by the glow plugs primarily right after the truck starts - check out  this Fluke log compliments of user MisterCMK on FTE.  While this 230 amp draw is not continuous, it stays for about two minutes at 0°F (-18°C), a minute and fifteen seconds or so at 32°F (0°C), and 45 seconds at 50°F (10°C).  This is hard on your batteries, hard on the amplifier that is the FICM, and hard on the alternator itself.

Adding insult to injury is that the stock alternator commonly fails in the 120,000-160,000 mile (190,000-260,000km) range and that when it fails, it commonly does so with a failed voltage regulator that very often doesn't even illuminate the battery or check engine light!

It might make sense to get a better alternator if:

1.  Your alternator is putting out less than 13.3 volts at hot idle (as measured at one of the batteries) with all accessories (headlights, blower motor, heated seats, inverters, radio, etc) on;

2.  You are close to the failure range in mileage of these alternator just anyway;

3.  You live in a climate that sees winter temperatures below 32°F (0°C) or so

If you've decided to get a larger unit, consider our proven performers, the USADiesel line of alternators. From our 185A to the 400A units, they're ismply hard to beat. We have raw finish options, and chrome for the guys looking to add a little "bling" under the hood. Very nice looking units.

The USA Deisel 185A unit puts out 135 amps at hot idle and maxes out around 190 Amps and is a very solid choice for you if you don't run a plow, winch, serious inverter, live in a warmer climate. If you live in a colder climate, consider how much of that initial 230 amp draw at startup you want to offset. (from the glow plugs) The better you're able to cover that draw, the better off you will be. 

If you DO run a plow, winch, or large inverter, the USA Diesel 240A, 320A or 370A, are solid choices. As indicated, we also offer the Leece Neville and DC Power alternators. These high output options are more money, sure, but you can run small cities with the power they yield, even at hot idle levels. Wow.

One of the features that set the USA Diesel line of H.O. alternators apart, is the lifetime warranty option. With that option, you buy it once and you're done buying alternators for as long as you own the truck. That's hard to beat.     

Of course, you should also consider coupling any alternator with auxiliary alternator wiring (see point 3 on this tips list) since the stock wiring size results in an excessive drop in voltage by the time it hits the batteries. A great discussion on all this, including the source of the above Fluke log can be found on FTE. DC Power posted a video showing the output of the 270XP unit as well.

Don't worry about over-charging your batteries with any of these options - the internal voltage regulator will only give the system the oomph it needs up to the capacity of the alternator but never more.

If your alternator is putting out the right voltage, but you are still concerned and just want a reason to move into a new alternator...we can help there too. We've seen many a FICM's logic board get completely fried by a bad voltage regulator - a common failure in any alternator even IF the voltage output measures within spec during your voltage test. It's a sad little reality. 

Hope this helps! 

               Simply search the keyword "alternator" on our site and all the options will display. Or, if you, like a lot of people are strictly intersted in the USA Diesel line, search "USA Diesel".