My truck, has also not started a few times. Taken batteries out had them tested, both 5xx cranking amps and 12volts about. Alternator, 12.8 to 14 volts. The truck sat for 4 days and started.

But today, it barely started, I drove for 15 minutes, shut it off and immediately it would not start. 11-12 volts, jumped it, and the alternator 13.5volts. When at idle the radio would shut-off, presumably from not having enough power.

 

Not 100% sure but 500 cranking amps seem low... The batteries in my truck are 1000 amps and the ford ones are 850 I believe...

The batteries were load tested.. were they fully charged first... The alternator is not a good way to charge a battery that is run down... Autozone will test and charge your battery for free...

 

i agree 500 is low. mine were 890 a month ago when i checked them

bad batteries will kill your alternator. charge them, load test them again. if good, but them back in (follow procedure in tech folder). if bad, get new ones.

crank truck wait 2 min (let glow plugs turn off and alt turn on) and test voltage again to make sure atl is still good.

be careful with your voltage, your ficm is sensitive about varying voltage.

gearloose1 is a electical guy that could also give you incite on this.

 

I charged the batteries for the test, they are the originals.

 

I thought that the motorcraft batteries were 850amps...

If the alternator is charging... cant see what would pull the battery down that quick... Did you test the alternator under load... (Light, heat, radio on) ... put it under load see what she puts out...

To me it sounds like your batteries are to small and are being drawn down by the glow plugs and the starter... also 15 minutes worth of driving isn't going to charge them up enough to start the truck again..Remember while the truck is running its not only supplying current to charge the battery but to all your electrical components as well...

Any cold weather were you are...

 

Batteries are not 850amps!!!

That is Cold Cranking Amps... a rating that can only be maintained for a brief burst.


Automotive battery - Wikipedia, the free encyclopedia

 

You are correct... Forgot the designation CCA....

 

With lights on, radio the alternator puts out 12.8 or so, at high idle, under load 13.5 or so.

And why is the passenger side battery wrapped in some insulation?

 

How about measuring actual amp output with a clamp on ammeter and a voltmeter to get an actual watt output?

 

I have a multi-tester, and I can probably test the amps, what should I get? under what conditions?

 

2,000 rpm, everything possible turned on, and see what the alternator is putting out.

 

Mine doesn't have the insulation.. I would say to either protect it from the heat under the hood.. Or to keep it warm as they do tend to warm up as they work....

I'm sure someone here knows and will step in...Especialy about how many CC amps are needed/recommended to start the 6.0...

Also more info would be usefull... Whats the temp were your at??? Do you drive it much?? and for how long???

 

What kind of numbers should I see?

 

Depends on your truck and alternator.

But the factory spec heavy duty alternator should deliver 110 amps.

That... @ 12V = 1,320 watt.

@ 14V = 1,540 watt.

That is, assuming you have the load to pull that much out.

If not.. proportionately less.

The electrical load for the vehicle with everything running is around 80 to 90 amps.

Don't buy non Ford OEM (and only the exact part number) specified alternators unless you like to do this over and over again... the wrong alternator will keep failing on you.

 

Second thought, I don't think my multi-tester will test over 15 amp. Can I just go by volts?