Battery light, 14.5 volts from alternator, remote start not working......

[RFink]

Battery light on, 14.5 volts from alt w/lights,blower etc on, remote starter not working, within 2 days battery is flat so I installed a battery disconnect on the neg terminal.


12.78 volts showing on multi meter from neg battery terminal to neg ground wire. Where do I start?

 

[Plati]

Can you post a picture of the battery disconnect?

 

[RFink]

Disconnect pic

 

[1955moose]

OK we've posted this but I guess nobody sees this, so once again, year, engine size , 2 or 4 wheel drive. We need a starting point. How long has this charging problem been going on! How could you have 14.5 volts running, and have battery light on? Have you or someone done any electrical work, I E, new stereo, alarm, lights, etc. By the way voltage tests are run across both battery terminals, or positive lead at back of alternator, negative to ground. Have you had alternator tested anywhere? It's possible your putting out voltage but not amperage, rare, but I've seen it.

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[deweysmith]

Pull codes. Battery light could mean more than one thing. If the light is on, a DTC is set somewhere.

 

[RFink]

03 - 5.4, 4WD EB
Pioneer stereo installed June

Around April, alternator failed, took out the battery replaced both Advanced Auto alt (3rd one worked) and Delco battery, battery light on since. Replaced alt. harness. Dec 1 battery dead. Store said battery took a big power spike. Replaced-lasted 2 days got the switch.

 

[stamp11127]

If you are really showing 12.78 volts from the negative terminal to the negative ground wire (with current flowing) there is high resistance in the cable connection that is forcing the high reading on the meter. What you have described is referred to as the "voltage drop test".

If you were trying to read the battery voltage the red lead is placed on the positive battery post - black lead on the negative post, meter set on DC volts.

 

[Plati]

If you are really showing 12.78 volts from the negative terminal to the negative ground wire (with current flowing) there is high resistance in the cable connection that is forcing the high reading on the meter. What you have described is referred to as the "voltage drop test".

If you were trying to read the battery voltage the red lead is placed on the positive battery post - black lead on the negative post, meter set on DC volts.

I was baffled by RFink's original post also ... that part about the 12.78V. Thought it might have been a typo. If his disconnect switch is located on the negative battery lead and disconnected... and he measures 12.78V across that disconnection, then I think that means the positive battery wire is connected to chassis ground somehow , right? I'd want to measure the voltage from the positive battery terminal to the negative terminal with switch disconnected (like you said) then move red lead of voltmeter to negative ground wire (disconnected from battery). If they are the same voltage and polarity then ... ?

Of course, vehicles with all these computers and semiconductors in them .. maybe that's normal. I'd have to try it out in another vehicle to see what is normal with the negative terminal disconnected to be sure myself. If you disconnect both battery cables (positive and negative) and measure a dead short (zero ohms or some small number) from the positive cable to chassis ground then I'd not be happy with that.

 

[1955moose]

Wow, I'm not nowhere in the league of you guys on electrical, but shouldn't the negative have no voltage between battery post and cable, when all is right? I know when checking for battery draw that's usually the way to check, by pulling fuses, till it drops. But almost battery voltage like He's experiencing, isn't that some sort of power grounding problem, allowing positive voltage to flip to ground? I know the 12 volt system starts at ground, opposite of common sense thinking, but that's the way a 12 volt negative ground system works. Could he have something with either his computer, or one of his components that caused this reversal of power. Every time I think I've seen or heard it all, something like this pops up. This will be a great finish, I want to hear this one.

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[stamp11127]

Lets wait for the OP to respond on the voltage readings before getting into what is happening with his problem. At this point nothing weird is going on.