battery warning light

[Zellerj]

Yesterday my battery warning light came on, and I pulled into an Autozone for analysis. The Autozone tech said the battery was good - passed a load test, and the alternator was supplying 14.2 volts to the battery under load and at idle. So the battery and charging system is good. Anyone have any ideas on what to check next?

What I have read and I will check: serpentine belt is loose, ground wires have poor connections, three part plug on alternator is corroded or loose, fuse is bad, relay is bad.

I live on a small island, and bought this vehicle last year to pull my 8000 lb boat up the ramp. So it sat most of the summer not being used very much because my golf cart is my go-to ride on the island.

6.2 L gas with 90000 miles. Love the ride.

I will report back.

Jim

 

[99WhiteC5Coupe]

Yesterday my battery warning light came on, and I pulled into an Autozone for analysis. The Autozone tech said the battery was good - passed a load test, and the alternator was supplying 14.2 volts to the battery under load and at idle. So the battery and charging system is good. Anyone have any ideas on what to check next?

What I have read and I will check: serpentine belt is loose, ground wires have poor connections, three part plug on alternator is corroded or loose, fuse is bad, relay is bad.

I live on a small island, and bought this vehicle last year to pull my 8000 lb boat up the ramp. So it sat most of the summer not being used very much because my golf cart is my go-to ride on the island.

6.2 L gas with 90000 miles. Love the ride.

I will report back.

Jim

I would closely examine the battery terminals, and battery terminal connectors.. Remove and clean them with a battery termite brush. Ensure that they are not loose when you reconnect them.

Rarely is the serpentine belt loose - unless severely glazed (very obvious).

I have been to Kelly’s Island, and my wife’s former boss used to own a golf-cart concession on the island. Very nice area.

 

[richs fishes]

So it sat most of the summer not being used very much

You sure its not just the battery? I'd grab a multimeter and test yourself a bit. Check the voltage with engine running and while its off. I've had to have alternators and starters (granted not batteries) tested multiple times at autozone before they'd actually fail. This was on an older Nissan and I knew they were bad so I insisted they kept checking so I could get the new part under the warranty.

 

[Flexpedition]

6.2 L gas with 90000 miles. Love the ride.

Is this a Ford pick-up? It really doesn't make any difference as the battery/charging system would be largely the same on an Expedition.

 

[Zellerj]

No my mistake. It is a 2012 Expedition with a 5.4 L engine. I tested the battery with a load tester, and it was good. Also the load tester after starting tested in the green, so 14 volts. My volt meter on the dash is straight up in the middle where it should be, and appears to be working.

I cleaned all of the battery terminals and the ground lug that bolts to the inner fender. They did not appear to be that bad, but I shined them anyway. The red wire coming from the alternator looked good too. I charged the battery with an external charger, and it took about 15 minutes for the amperage to drop to below 5 amps. While charging I started the car and the green battery symbol was gone. Took the charger off and went for a test drive, and the battery symbol appeared again soon after starting.

Perhaps my alt is putting out 14 volts, but the output amperage is low. Does the green battery symbol come on with low amperage coming from the alternator, or does it come on with low voltage?

 

[HawkX66]

The newer Expys (not sure about 2012) have a battery save feature that won't allow the accessories to stay on if your battery is weak. My 07 doesn't have it that I've seen, but my 2017 does. After I fixed my 2017 I had to go through an easy routine to reset the ECU. You might want to look into whether or not something like that is causing the error msg.

 

[MuddySpokes]

While this might not be it, I have seen alternators start to fail where the indicator is an on / off type behavior. Only way to see this happening is with a voltage gauge. As the alternator starts to die, the gauge (presuming an analog one) will look like a slow tail wag as the system voltage goes from the 14.X to 12.X range and back. The cycles usually took ~20 minutes to go back and forth.

 

[chuck s]

Neither of my Expeditions can go a month without the battery being dead. I assume you fully charged the battery after it's summer siesta?

"Island cars" tend to have problems based on inactivity. I'd put some miles on the car and see if it fixes itself. Hop on the ferry, drive to Cleveland, and watch the Indians afternoon game. Put some heat in the whole system.

-- Chuck

 

[Zellerj]

Update. Since I noticed that the battery light does not come on when the battery is hooked to an external charger, and without the charger the alternator, while the engine is running, gives 14.2 volts to the battery, I thought that maybe there is a ground issue with the alternator. And so I removed the alternator and shined up all of the connection points to the block. Upon starting I was pleased to see 14.6 volts at the battery and I thought that I had solved the issue. However, even with 14.6 volts charging the battery, the battery light stays on. Now I am thinking that even though the battery tests fine using a load tester, it probably needs to be replaced. Any comments?

 

[stamp11127]

The alternator is controlled by the pcm now. The signal that is going back, if there is one, is telling it that it isn't charging. Therefore you have a battery light on.

Which type of load tester did you use on the battery?