Errant Battery Light
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From: Cincinnati, Ohio
Errant Battery Light
Hello all,
Am looking for any guidance the group can offer about the battery light in my ‘96 Ranger XLT. The light came on intermittently after I replaced a dead battery, then began staying on. The battery and alternator both test as good. Lights are bright and it starts right up, no slow grind or anything. I even pulled the neg battery terminal while running and it stayed running. Any ideas?
Thanks in advance for your help.
Patrick
Am looking for any guidance the group can offer about the battery light in my ‘96 Ranger XLT. The light came on intermittently after I replaced a dead battery, then began staying on. The battery and alternator both test as good. Lights are bright and it starts right up, no slow grind or anything. I even pulled the neg battery terminal while running and it stayed running. Any ideas?
Thanks in advance for your help.
Patrick
Welcome to the forum
Don't do the Negative battery cable test any more, it will damage electronics in newer vehicles.
Just FYI, the battery "acts" as a large capacitor when alternator is on, alternator provides minimum 13.5volts, battery is only 13volts max.(new) and 12.5v usually so the battery absorbs voltage while alternator is working, this keeps it charged up and it acts like a capacitor, it will absorb Voltage Spikes that occur in spinning alternators.
Older cars had very forgiving electrics, usually rated for 0v to 30v, lol
Electronics are not so forgiving, and this includes the now electronic voltage regulators in the alternator.
This is also why you should NEVER use Jumper Cables from a running engine, you can damage BOTH vehicles
If you need to jump then leave engine off, if possible pull off one battery cable
Use only the battery to boost dead batteries power for starter motor, and when started it WILL send a Voltage spike out because of the low/dead battery, which is why you don't want the other car running.
Battery Light on the dash works by GROUNDING
On the alternator there is a 2 or 3 wire connector, that's for the voltage regulator
Green wire on this connector is the GROUND for the Battery Light Bulb in the dash
Turn on the key
Battery light should be on
Unplug this connector from alternator
Battery light should be OFF, jiggle the wire to make sure it is not shorted to Ground anywhere
Use a Volt meter and test Green wire, it should show Battery Voltage, 12.3-12.8volts, unplugged from alternator with key on, jiggle wire as well
Yellow wire on this same connector should have Battery Voltage key off or on, its from a 15amp fuse on engine fuse box, fuse #17 I think
Battery Light comes on when alternator voltage drops BELOW Battery voltage, like when key is on and engine is off alternator voltage is 0 so battery light comes on
If battery light is flickering or coming on then at that time alternator voltage is BELOW battery voltage, so under 12volts
You can test this at the battery with engine running
Engine running Voltage at the battery should be 14.8v down to 13.5volts, never lower
If you see it drop every once in awhile, I would change voltage regulator, or alternator.
New used to mean "tested and working"
New now means "You test it, and we will replace it if it doesn't work"
There is no Quality Control, it is too expensive, Ford still requires it which is why Motorcraft parts are so darn expensive, but 3rd party "New" doesn't mean it works, just means its never been tested
Don't do the Negative battery cable test any more, it will damage electronics in newer vehicles.
Just FYI, the battery "acts" as a large capacitor when alternator is on, alternator provides minimum 13.5volts, battery is only 13volts max.(new) and 12.5v usually so the battery absorbs voltage while alternator is working, this keeps it charged up and it acts like a capacitor, it will absorb Voltage Spikes that occur in spinning alternators.
Older cars had very forgiving electrics, usually rated for 0v to 30v, lol
Electronics are not so forgiving, and this includes the now electronic voltage regulators in the alternator.
This is also why you should NEVER use Jumper Cables from a running engine, you can damage BOTH vehicles
If you need to jump then leave engine off, if possible pull off one battery cable
Use only the battery to boost dead batteries power for starter motor, and when started it WILL send a Voltage spike out because of the low/dead battery, which is why you don't want the other car running.
Battery Light on the dash works by GROUNDING
On the alternator there is a 2 or 3 wire connector, that's for the voltage regulator
Green wire on this connector is the GROUND for the Battery Light Bulb in the dash
Turn on the key
Battery light should be on
Unplug this connector from alternator
Battery light should be OFF, jiggle the wire to make sure it is not shorted to Ground anywhere
Use a Volt meter and test Green wire, it should show Battery Voltage, 12.3-12.8volts, unplugged from alternator with key on, jiggle wire as well
Yellow wire on this same connector should have Battery Voltage key off or on, its from a 15amp fuse on engine fuse box, fuse #17 I think
Battery Light comes on when alternator voltage drops BELOW Battery voltage, like when key is on and engine is off alternator voltage is 0 so battery light comes on
If battery light is flickering or coming on then at that time alternator voltage is BELOW battery voltage, so under 12volts
You can test this at the battery with engine running
Engine running Voltage at the battery should be 14.8v down to 13.5volts, never lower
If you see it drop every once in awhile, I would change voltage regulator, or alternator.
New used to mean "tested and working"
New now means "You test it, and we will replace it if it doesn't work"
There is no Quality Control, it is too expensive, Ford still requires it which is why Motorcraft parts are so darn expensive, but 3rd party "New" doesn't mean it works, just means its never been tested
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