Battery light on acceleration

[muzzymaniac]

Just like the title. When I drop the pedal hard the battery light comes on and the lights dim. The truck accelerates like I expect but the lights dimming suggest a power issue. Anyone have any thoughts?

 

[manaen]

Your alternator needs to be load tested, it is also possibly a wiring problem. But since it is RPM related I would take the alternator out and have a local shop load test it. Then go from there

 

[Rocketheavy]

samething

Same thing happened to me. it was my altenator and they arent cheap either

 

[90ranajo]

Also you might want to check your belt and belt tension. I've see it where the belt had glazed and under high load rapid RPM transients the belt would slip cause eratic behavor on some accessories.

 

[Charlie]

Doesn't the alternator disengage under heavy acceleration, or am I thinking of something else? Maybe I am just crazy.
Defiantly get it tested though.

 

[muzzymaniac]

Only happens when I put the petal to the floor. First thing I know I need to do is check the battery cables and other grounds. I was curious to see if anyone has experienced similar. That would suck if it was the alt - it only has 28k on it!

 

[manaen]

Doesn't the alternator disengage under heavy acceleration, or am I thinking of something else? Maybe I am just crazy.
Defiantly get it tested though.

your thinking of the air conditioning pump.

 

[manaen]

Only happens when I put the petal to the floor. First thing I know I need to do is check the battery cables and other grounds. I was curious to see if anyone has experienced similar. That would suck if it was the alt - it only has 28k on it!

well then it should be under warranty..

 

[muzzymaniac]

It's an 04. Warranty may be up. I bought it used. The warranty goes by the original purchase date, correct?

 

[manaen]

It's an 04. Warranty may be up. I bought it used. The warranty goes by the original purchase date, correct?

should be a combination of mileage and purchase date. usually its 36months/36k I think that is the powertrain side of it. Either way call the local ford dealer they can lookup your warranty info by plugging in the VIN. Then you know for sure. Oh wait, the alternator is not powertrain, well it's worth the call to find out. The original owner may have purchased an extended warranty, I think it transfers with the vehicle.

 

[VoltsAndBolts]

Do you do a lot of; “Foot in the floor driving“? If you don’t I wouldn’t sweat it sense the problem isn’t there under normal driving conditions. If you have a part failing you have some time to save the cash for the replacement. Then if/when it fails. Replace it. Just my $0.02

 

[muzzymaniac]

Do you do a lot of; “Foot in the floor driving“? If you don’t I wouldn’t sweat it sense the problem isn’t there under normal driving conditions. If you have a part failing you have some time to save the cash for the replacement. Then if/when it fails. Replace it. Just my $0.02

Ummm No I don't do a lot of of that driving but that doesn't mean a problem should be ignored. If you have a real bad front end shake @ 50 mph and over but rarely go those speeds would you ignore it?

 

[spkhone]

sounds like you alternator. happened to me. was washing my ex at a drive through carwash, and the battery light started flashing for a little bit. got it checked at autozone and told me my alternator wasn't holding at peak. how hard is it to change out.

 

[manaen]

sounds like you alternator. happened to me. was washing my ex at a drive through carwash, and the battery light started flashing for a little bit. got it checked at autozone and told me my alternator wasn't holding at peak. how hard is it to change out.

it's not a difficult swap, can be done in about 15 minutes, just a matter of removing the air intake, then the serpentine belt and unplugging and unbolting the old alternator. The unit can be rebuilt at a local automotive electronics shop, that is your cheapest bet. I just had mine done for about $100. They had a rebuilt unit on the shelf so I walked out with a unit, otherwise I would have dropped mine off and picked it up in a few hours.

 

[VoltsAndBolts]

I didn’t say ignore it, what I was saying is your going to have to replace a part. If your truck is not suffering ill effects other than the light you have time to save and prepare for that failure.

Comparing a front end shake to an idiot light is a little disproportionate. In any case it sounds like a weak diode in the alt. Get it tested. I hope you find your issue.

 

[MustangP51]

its the alternator, and don't do what i did and not fix the problem. The battery light would come on when over 3k RPM in my Expedition, and I let it go for several weeks. Then I was on my way back from a relatives house at 11:00 at night on the highway and the alternator failed, The battery got me to the exit I needed to get off at, but i had to sleep in it in a McDonald's parking lot overnight. My advise bite the bullet and fix the problem mine was about $180.

 

[muzzymaniac]

I had it tested at Autobone and they said volt were plenty but it was only putting out 3.5 amps max and it actually dipped negative under load. Now, the one thing I noticed was that the belt tensioner was really jumping around. The belt looks great and the truck only has 29k on it. Could the tensioner make that much of a difference? I haven't pulled the belt off to see if there's a lot of play in the tensioner yet - maybe a little later.

 

[DeSOB]

I had this same problem with my '05. 54K miles on it. I had the extended warranty and they replaced the alternator.

I figured I should join the site if it already helped me with a problem.