Well i have an old 86 ford f250 that wasnt starting unless the batteries were on the charger. So i bought 2 new batteries and a new alternator and voltsge regilator because it wouldnt keep the batteries charged now after starting the truck and unplugging the batteries to test the alternator it says its putting out high power but when i plug the batteries back in it drops way low on the guage. Any ideas? Thank you

 

never trust the factory gauges for one.

get a multi meter and see what it is charging at when the truck is running.

 

I have an aftermarket tester it says 14 volts when the cables are off the battery 12.5 when theyre on

 

u should never run it without the cables hook to the battery. can fry the voltage regulator and or the alternator.

and so with the wires hooked up, you are only seeing 12.5 volts at the battery?

 

Ok i wont do that anymore but yeah its lmly 12"volts at the battery

 

does it raise when you rev it?