charging system

[hidriller]

I have a 1984 ranger 2.8L motor.Never had a problem keeping battery charged.Now my voltage at the battery drops when I start the truck.Checked and cleaned cables and groungs.nothing so I replaced the alternator, and still low voltage.So I changed the regulator,which also did nothing.Now I'm stuck to daylight driving untill I figure this out.I don't have to much hair on my head to begin with,please help me keep it

 

[Andy D]

how old is the battery? Sounds like it may have an internal short.

 

[nitrofan1]

The alternator is a standard 42amp 7078 series with external regulator so it's a simple system: alternator, regulator and battery. The regulator reads voltage drop of the battery and opens up to allow the alternator to charge the battery. Check the battery at the terminals for 13 volts unloaded and 13.5 to 14.5 volts loaded (lights, heater etc... on) Anything below 13 volts the alternator isn't doing it's job.

How old is the battery? Does the battery have the cold cranking amps and reserve minutes the Ranger requires? Added components (lights, winches, stereos etc.. add drain to the battery). If the battery is more than 3 years old take it out and have it tested at a parts store. It may have a weak cell which should show up during testing.

 

[kimcrwbr1]

First off you need to clean/sand all the grounds metal to metal. Being winter new cables wouldnt hurt either somtimes the cable will have corrosion under the insulation you cant see. fully charge the battery and check the voltage say 12.8 volts. Start the engine and after a few minutes at 1500 rpm it should be no higher than 2 volts or no higher than 14.8 volts that is the no load test. Then turn the lights on heater on high and radio on and at 2000 rpm the voltage should be no lower than .5 volts of batt voltage or no lower than 13.3 volts that is the load test heres the link to the tech library for diagnostics but it is usually a bad ground somwhere. Make sure all the wiring is good then continue with the diag.

 

[kimcrwbr1]

http://www.therangerstation.com/tech_library/chargingsystem.htm oops sorry