Battery Light

[Brad]

Does the Battery light strictly mean the alternator or could it be related to he battery? Yesterday and today I got the light for a few seconds while coasting.

[007Cruiser]

Re: Battery Light

Per the owner's manual, the warning light indicates a problem with the charging system:

"Charging system: Illuminates when the battery is not charging properly."

[Brad]

Re: Battery Light

I'm continuing to have this issue....but only when the temperature is above 40 degrees. After about 20 minutes of driving the battery light will come on for a few minutes and then it goes off. I can make the light go off right away if I accelerate and hit the passing gear which would logically make sense with a weak component in the alternator, but seems odd with never getting the light in cold weather. I've had it in the shop and the alternator tests fine and they couldn't see any issues with the pulley/belt and the car always starts just fine, battery is about a year old.

Any ideas? Does anyone have a schematic of that circuit? Wondering if the idiot light is routed through the FEM or other module?

[HKS]

Re: Battery Light

I'm continuing to have this issue....but only when the temperature is above 40 degrees. After about 20 minutes of driving the battery light will come on for a few minutes and then it goes off. I can make the light go off right away if I accelerate and hit the passing gear which would logically make sense with a weak component in the alternator, but seems odd with never getting the light in cold weather. I've had it in the shop and the alternator tests fine and they couldn't see any issues with the pulley/belt and the car always starts just fine, battery is about a year old.
Any ideas? Does anyone have a schematic of that circuit? Wondering if the idiot light is routed through the FEM or other module?

It could still be the alternator. The internal regulator components may fail with temperature (high or low). A bad regulator might even cause high voltage and the light may come on. Racing the engine may warm the alternator solid state components and effect the intermittent component.

Substitution is the best way to troubleshoot. If you have enough mileage on the car than it may be justifiable to just put a new alternator in. Do not install heavy duty alternator in place of the OEM spec. I will explain as to why if you like.

HKS

[Brad]

Re: Battery Light

The car has 10K miles but had been stored until recently, issue started after a few months of daily driving so it could be related to sitting for all those years. I figured I would wait until the light stays on longer to have it replaced. I'll feel real silly if I replace it and then still get the light.

A few months ago I had my wife's car on the roadside due to a bad alternator where the light never came on and then the car died when the battery was dead. Replaced the alternator and started getting the light (bad rebuild).

I'll bite, didn't know a heavy duty was available but why not?

[AZTB]

Re: Battery Light

My '05 had this issue early last year, but it didn't show up in the warning light in the instrument cluster, but rather the light/signal/security receiver "button" in the middle of the dash (raised button close to windshield).

Car had not been driven in about 10 days. When I started the Bird, it cranked like the battery was drained (but it did start), and then the button stayed lit and would flicker on and off for the next few miles...it eventually went off completely and no further issue was apparent.

[SugarDaddy]

Re: Battery Light

For the last 3 years, we have had this issue with the battery warning light illuminating for several minutes (about 3 to 4 minutes), after driving the T-bird for about 3 minutes.

Take a look at this thread on TBN: http://www.thunderbirdnest.com/forum...ad.php?t=41057

The 5 year old Motorcraft battery was replaced last year by my dealer, with a new Motorcraft vented battery.

The battery warning light still comes on after a few minutes of driving. The warning light stays on for several minutes, and then goes out. It never leaves an error code, so the dealer’s technicians can never solve the problem.

At all times, I carry a plug-in volt meter, which plugs into the power outlet on the center console. When the battery warning light comes on, I plug that volt meter into the power outlet while driving. The volt meter usually reads between 14.0 and 14.3 volts at the power outlet, even though the warning light is on. So apparently, the alternator is powering the system during these episodes. During these episodes, I have never had a situation where the voltage drops below 13.2 volts while driving.

I have also checked the alternator output during these episodes while the battery warning light is illuminated, using my OBDII Bluetooth Adaptor for Android and the “Torque” app on my smartphone. The alternator output is always in the good range (13.2 V to 14.3 V), even while the warning light is on. There is never an error code set during these episodes.

Our T-Bird runs fine otherwise. I have had the serpentine belt and idler pulley checked and they are fine.

It’s still a mystery to me what is going on. Maybe some one knows how to solve this problem?

[HKS]

Re: Battery Light

The car has 10K miles but had been stored until recently, issue started after a few months of daily driving so it could be related to sitting for all those years. I figured I would wait until the light stays on longer to have it replaced. I'll feel real silly if I replace it and then still get the light.
A few months ago I had my wife's car on the roadside due to a bad alternator where the light never came on and then the car died when the battery was dead. Replaced the alternator and started getting the light (bad rebuild).
I'll bite, didn't know a heavy duty was available but why not?

Heavy duty.
In order to push extra current to (assuming added accessories) the alternator also puts out a higher voltage. Instead of14.3 volts it might be 14.75 volts. Good for short trips but bad for long trips. It will shorten battery life due to some overcharging.

HKS
P.S. Sometimes a heavy-duty alternator requires a longer serpentine belt. Like in a 2002 Chevy pickup.

[Brad]

Re: Battery Light

Hmmm. Do you know if the battery light connects to the FEM?

Does the Tbird have a "overrunning pulley decoupler that allows the alternator to momentarily disengage from the belt drive where there are sudden changes in belt speed"?

Since my issue seems to be heat related the only variable electrical component I can think of on an 02 is the windshield pad heater which only comes on under 32 which is exactly when I don't have my issue...would be interesting to know if that routes through the FEM as well.

With a fully charged battery would you see much fluctuation on your meter if the alternator was unplugged for a short time?

Have you done any electrical modifications? The only thing I have done is adding a circuit for an iPod to attach to the radio, I'm going to try uninstalling to see if there is any difference.

[HKS]

Re: Battery Light

Hmmm. Do you know if the battery light connects to the FEM?

Does the Tbird have a "overrunning pulley decoupler that allows the alternator to momentarily disengage from the belt drive where there are sudden changes in belt speed"?

Since my issue seems to be heat related the only variable electrical component I can think of on an 02 is the windshield pad heater which only comes on under 32 which is exactly when I don't have my issue...would be interesting to know if that routes through the FEM as well.

With a fully charged battery would you see much fluctuation on your meter if the alternator was unplugged for a short time?

Have you done any electrical modifications? The only thing I have done is adding a circuit for an iPod to attach to the radio, I'm going to try uninstalling to see if there is any difference.

Good logic.
Thinking real gages would have been helpful instead of idiot lights operated by a computer. I would be tempted to run a temporary wire from the battery to a volt meter in the cabin.

HKS

[Rondor]

Re: Battery Light

I would guess it's a bad battery. A cell shorting out can cause some really strange and intermittent problems. I would have battery tested first. I have had this issue many times on many Fords.

[Brad]

Re: Battery Light

The thing is mine is highly predictable.

Outdoor temp below 32, NEVER get a light (today)

Outdoor temp above 32, light, comes on after about 20 minutes of driving for a few minutes, EVERY TIME I drive the car. (yesterday) Randomly after the first time it comes on it may go on and off a few more times during my drive.

[HKS]

Re: Battery Light

The thing is mine is highly predictable.
Outdoor temp below 32, NEVER get a light (today)
Outdoor temp above 32, light, comes on after about 20 minutes of driving for a few minutes, EVERY TIME I drive the car. (yesterday) Randomly after the first time it comes on it may go on and off a few more times during my drive.

Brad,

Battery temperature would rise if a cell shorts out, and this would also put a strain on the alternator electronics. In this case a real voltmeter would be a great help.

HKS

[steelblue5505]

Re: Battery Light

I would guess it's a bad battery. A cell shorting out can cause some really strange and intermittent problems. I would have battery tested first. I have had this issue many times on many Fords.

I too think the problem is nothing more than a BAD battery.

This issue is common with today's batteries & today's vehicles' heavy demand on very good battery performance. Has nothing to do with the vehicle manufacturer.

[Brad]

Re: Battery Light

I too think the problem is nothing more than a BAD battery.
This issue is common with today's batteries & today's vehicles' heavy demand on very good battery performance. Has nothing to do with the vehicle manufacturer.

My initial instinct was to replace the battery but it's just over a year old and tested fine (but I'm also not convinced it isn't the issue)