Hello everyone. Just another old person trying to help a younger person with his truck. actually the grandson, but he is learning !!!!

For me, have had to work on my own stuff since high school - last century - but liked it so well, I still do it as much as I can, the new stuff really confuse me and fluster me sometimes with all the computer stuff that is involved but I work around it.
I have other likes, shooting regularly, driving the old hot rod - with old 4 speed and staying in the garage out of the wife's way - somehow I keep getting under foot or ask too many questions.


Am retired from welding in nuclear plants since '86 and a 'nam veteran

grandson has a '03 ranger 4.0 eng. the alt. went bad, then the battery. Now he says the truck has a weak start with new battery and new alternator that was way over priced. The response we have received so far is that the new alternators will no longer put out 14.4 but the new acceptable range is 13.7 to 13.9 - this is not acceptable to me since everything I have puts out the 14.3, 14.4 range

What other alternators will interchange with this alternator - ?? There is a local person that is old school and guarantees his work to be just as the old school stuff

thanks for anything that you can provide and yes even tho my favorite is the 55 chevy, 327, 3x2, and 4 speed, there are 2 shelby mustangs siting in the garage - belongs to the wife 1 is just a shelby gt and the other of course is the 500gt - both convertibles, both same color, both same year and both with mileage within 1000 miles of each other

yes - I have too many toys

 

Welcome to the forum

I am an old guy too

Maybe you mis-remember the voltages

12volt alternators put out 13.5-13.8volts as the "run" voltage to power the vehicle, should be 1.1v above battery voltage, this is called "maintenance charge", keeps battery "topped up"

Just after start up battery is drained so alternator will output up to 2.0volts above battery voltage, so 14.5-14.8v, this is "quick recharge" level

This is "at rest" battery voltage, i.e. after battery has been sitting for at least 2 hours, 8 hours is better(overnight)
A new battery will be 12.8v
3 year old battery 12.5v
5/6 year old 12.3v and time to shop for battery sale

12.2v and lower is dead or dying battery


If alternator stays above 14volts after say 15 minutes of run time then battery will get "cooked", voltage regulator needs to drop voltage down to under 14volts for sure or it will ruin the battery long term

So Yes, if you test voltage just after startup it for sure should be above 14volts(but under 15volts)
But if you test it after a drive, WITHOUT shutting off the engine, then if should be 13.5-13.8volts, if its higher then it will cook/kill the battery


Voltage regulators work by "push back" in the vehicles electrics, so its not actually a "set voltage" but pretty close
When you start the engine the battery is drained so has little "push back", as it recharges it starts to "push back" against the voltage coming in, so voltage regulator dials down the alternators voltage.
If a battery is "bad"/failing, then it won't "push back" as much and voltage can stay high, which finishes off the failing battery, lol
So test battery voltage FIRST, after it has been sitting, once you have that voltage you can determine alternators condition
With engine running and voltage meter on battery, read voltage, say its 14.5v, raise RPMs to approx. 2,000 and hold it there
Voltage should go up a bit and then DROP BACK DOWN to 14.5v, thats the voltage regulator working
If voltage goes up and down with engine RPMs then voltage regulator is stuck its not able to vary the output voltage, and this can cook/kill a battery, since you spend more time at 2,000+ RPM than at idle