marauder battery light on... Ford guys tech support
 

Hi guys
Battery light appears on my dash on my 03 marauder 4.6 liter..The factory volt gauge reads 10 volts, my meter reads 10.3 volts running, shut the car off the battery voltage jumps to 11.5 v. So I say alternator, buy one on line New not reman. install it today. The inside voltage gauge reads 14 and so does mine 14.1. Alls good right, wrong, you start the car,no battery light till about 2 mins later,... any ideas, the car cranks over fast and starts all the time, possibly a bad alt out of the box ?????

Did you charge the battery before installing the alternator? A low battery can burn up a new alternator because it is not a battery charger. An alternator is designed to maintain a battery. A low battery can overwork the alternator.

battery
 

the battery voltage was 11.5 when I removed the cables to install the alt, I did charge the battery @ first, so I did not charge it awhile after the battery light went on. only about 20 mins
Thanks

Re: battery
 

11.5 is a low battery... gotta make sure your battery isnt bad cause bad/loose lead plates can cause the same problem. battery should always be around 12 1/2 volts or more and around 14volts at idle.

battery light
 

I will install my spare chevelle battery that is a fully charged ( known good) and ready to go, that will tell me if the battery is bad, thanks for the tech support.

light
 

I put a battery in the car, used but known good,same problem. I did charge the current battery in the car, it now reads 12.4 v and when I run the alt at idle its 14.1. and it also kicks on the battery light still. gonna clean up the grounds and see what happens ????

Check the fuses as the computer controls the alt.

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I will, but when the car first starts no battery light appears,it within a minute it shows up, still a fuse issue ???

First, an Alternator WILL charge a battery. That's because the alternator is a dumb electricity generator. It just maintains a constant level of power to the battery and across the spectrum of your car's voltage/amperage requirements.

But it also has a lot to do with the battery type. Some batteries charge with an alternator better than others.

The old Lead/Acid batteries are the slowest to come back up, and if you just so slightly tip an older battery you've probably stirred up the crap in the bottom and shorted out a cell (or two). A battery of this type is usually considered "dead" at 10.5 volts.

With the "Gel Type" batteries, most are "deep cycle" and can be drained down to about 5 volts before they become difficult to recover, and with the little "Dry Cells", they're pure deep cycle and can be literally drained to nothing and yet recover in about 15 minutes.

It is a very good idea to start out with a fully charged battery (13.2 Volts)

The reason I state, emphatically, that an alternator is a battery charger is because that's what it does . . And it's the first thing it does after you start your car . . You pull about 2.5 volts , on average, when you start your car if it's a relatively new one with a computer, a HEI and a stereo. Those volts have to be replaced, and your alternator does that "on the Fly", while powering up your power seat, headlights, windshield wipers, etc . .

In the case of bixblk, it would sound like a "controls" (computer, ECM, etc) problem, but with todays systems, unless he can chase it down with an OBD box or get lucky and find the right dirty connection (Which is probably 50% of all electrical problems in the modern automobile) I certainly don't have even an educated guess . .

light
 

I spoke to my buddy thats wrenches on ambulances and he said he has seen a bad diode kick on a battery light, but with a meter it appears to be charging, makes sense cause the didodes make the ac to dc ,but a regular meter may read it as a dc charging voltage. His tester/ machine is sophisicated enought to detect a non dc waveform, I dont like to bother him on mondays cause he is repairing the ambulances from the w/e. I gonna take the alt to a store to test it, it maybe a diode issue. Or a computer, but the alt is new.

Sounds like you're on the right track.

Keep us posted on the outcome . .

It's cool to learn stuff . . . .

Most cars and trucks today have the voltage regulator in the computer. The computer controls and keeps the volts and amps at a steady rate to keep from having voltage drops. The lite will come on if there is one thing out of range, like if you turn on your head lights and pulls to much volts.

I had a Ford Freestar in my shop with the alt lite on, replaced a blown fuse just to find out the alt was bad to. I put a new alt in and after a few seconds the lite came back on. I hooked up my scanner and everything look gook, this thing drove me crazy. I called up a buddy of mine from ford dealer and he brought over there lap top and i was amazed at all the wave patterns that the alt was putting out, a/c, fuel pump, cooling fans etc. I looked at him and said dam I need that lap top as my scanner don't pick up half that, anyways after looking at everything he found nothing wrong but the lite was on. I went back and replaced the battery with a new one and still the lite was on, check the amps and the volts at the bat and at the alt check good. I went back to the fuses and the fuse I had already replaced had blown again so I replaced it and all was good. I am not saying that that's your problem just something to check as there could be a number of things. Good luck Just trying to help.

The cars and trucks today are getting to be harder and harder to fix with all of the elc crap on them and running though the computer.

yep... and ford also has a low voltage wire that sends a signal to the alt that turns on the alt after it starts.

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I will dig into it tonight, I do appreciate the tech support. Thanks
I also alerted the company that I bought the alt from to see if they any suggestions...

sigh.....I miss the good old days of generators...... :cry: :cry:

the light
 

Rechecked my work seems to be OK, spoke to a tech @ the company where I bought the alternator, seem to be good dudes, he wants the numbers off the original alternator to verify I have the right one. Did not check any fuse yet, thats next after speaking to the alt guys.

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the manu. says proper replacement, gonna send another alt, ..will update when more happens
jeff

It is possible that you got a defective alternator but the charge circuit and indicator are controlled by the PCM. The alternator still has a regulator built into it on that model. You really need a good scan tool to properly diagnose the problem.

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I am lucky enought to have some buddies in the mechanic trade, so I may be there next, weather here is hot as hell and they work w/o AC no need to bother them (yet) . They have scan tools , I got another alt coming, so when it comes I will install it and if the same problem scanner time. Thanks guys so far, alot of good support. I will update when I get it figured out, but still open to suggestions. Stay cool

light still on
 

new alt did not fix the problem, started checking fuses, all good so far ??????