Looking to fit 120amp alternator to 2009 PK Ford Ranger

So where is the power going? From my perspective, you should not have a problem.
Cheers,
Peter
OKA196 motorhome

A victim of the smart alternator?

What are the symptoms that make you think your current arrangement is not up to scratch?

All you need to do is get your for dealer to turn on the dual battery mode, alternator voltage will then return to normal levels.

The newer cars with a smart alt dont charge at a high enough voltage to service deep cycle batteries. The way around it is to fit a dc to dc charger between the car battery and the deep cycle ones. Totally keeps the fridge system seperate to the main car system. I ran similar in my 200 and ran a fridge 24/7 in there no issues, still do, so look at a 30 or 40 amp charger that you can hook a solar panel to, and your set.

I may be wrong but I don't think the 2009 PK Ranger has a smart alternator - I believe they came out in the newer PX ranger in 2011 !

You do know that a PK Ranger is not made for a larger output alternator.

Dont play with the alternator fit a dc/dc charger.

Dont play with the alternator fit a dc/dc charger.

Thnx to all who responded - will go down the DC DC charger road

Doing a quick “Google” search, PK Ranger alternators put out between 130 and 180 amps depending on the model. Perhaps do a search of the parts list for your model ranger to get the definitive answer.

Macca.

I’d would b testing the alternator and make sure it can put out the said amps.
Then test both batteries and see their capabilities and test the amp draw on both fridges.
If your not using a 12/12volt charger and charging the 2 fridge batteries through a VSR depending on your wiring size and length they can draw 45 to 50 amps each if there in a low state of charge.
Eg, my Engel draws about 4amps over about 14hrs at a 50% duty cycle it will take about 30amp-hours out of a fully charged battery.

When you restart your vehicle in the morning you will be using more amps than the alternator can put out so your start battery will discharge to make up the difference.
As the fridge batteries charge they will draw less and less amps and there will be a time when the alternator will be able to recharge all 3 batteries.
Unfortunately you will have dull lights etc through the first phase of this charging cycle.

Under this circumstance you would best fit a 12/12volt charger, a 30amp charger draws between 35 to 45amps from the start battery/alternator depending on wiring etc.
this would then leave enough reserve amps to run lights etc at charge voltage.

The difference between the 2 charging systems is time it takes to charge the fridge batteries, the 12/12volt charger will start putting 15 amps into each fridge battery where the direct connection through a VCR will start 45 to 50amps.
So if you can’t get a 120amp or higher alternator the 12/12 volt charger is the way to go with an 80amp alternator.

Keep in mind that alternators are designed to charge wet cell batteries and they don’t charge AGM batteries properly, a multi stage charger is best, also most 12/12volt chargers have a solar inputs, adding a panel on the roof will also help charge those fridge batteries.