97 CHARGING VOLTAGE
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97 CHARGING VOLTAGE - 10/23/2005 12:12:03 PM
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goodnused
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This is a 1997 ford F150 4.8L I am not satisfied with the charging voltage. I am reading 12.3 volt with the vehicle running. The guage shows mid to upper range on the dash charging indicator. I am use to seeing about 13 volts on most cars after an engine starts. And this truck..doesn't seem to really increase very much on a digital meter. I know this system may be computer enhanced in some way.
Not sure if I am in the dark or what here. I don't have any books that show the acceptable charging voltage range. So I may be worrying about nothing. If anyone knows these spec's I would appreciate replying and printing them. I got this vehicle after 3 other people worked on it. Just trying to make sure the vehicle is charging correctly before I give it back to the lady who owns it. Doing the job as a favor. I put in the proper new battery. And had the altenator checked at two local electrical shops. They said it worked fine. I just am not satisfied with a 12.3 to 12.5 battery voltage reading when running after starting a number of times.
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RE: 97 CHARGING VOLTAGE - 10/23/2005 9:11:20 PM
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hockeyhitman69
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you should have 13 to 14 volts at 12.3 or 12.5 thats just the battery and it is not charging
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RE: 97 CHARGING VOLTAGE - 10/24/2005 2:31:40 AM
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goodnused
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Thanks HockeyMan for your reply. I agree and my automotive educations agrees with your thoughts of 13.2 to 13.4 volts. I am not sure if your numbers came from a ford Manual or what?
The problem with this system is...the battery is fully charged..and two days old. I had the alternator checked at a auto electric and a Kragen auto parts store. Both of them said...the alternator was in 100% working condition, to include the regulator and diodes.
I did a circuit continuity test of all th wireing from the battery to the alternator. I had continuity..ohms...and full battery voltage as well. The only wire I really couldn't test was the one that went into the computer. But I did test it with a ohm meter...from the connector on the back of the alternator to the computer. All wires appeared to be in working order.
The dash idiot light...doesn't work...but the guage instrument...shows the level indicator to be at an exceptable level. Below 8 or above 18 is unacceptable according to the owners manual. And I would guess to say that the needle indicator is around12+ to 13..as a guess. But I just don't see satisfactory readings on my digital volt meter...which I know is very accurate. And Im not sure if the computer enhancement of this system...actually controls levels of voltage....Anyway...I have checked everything actually twice on and off the vehicle. And all the regulator fuses and BAT + fuselinks. So..who ever knows the answer to this...is up to speed on the system...or has had this same problem....or maybe fear of the voltage readings? Thanks for any input or replys by anyone. Goodn.
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RE: 97 CHARGING VOLTAGE - 10/25/2005 6:49:06 PM
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hockeyhitman69
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i am not a ford electrician(cars are getting to that point thou) but a licensed tech and your regulator is not working or you have a open in that circuit.on your altenator the big wire cable check it with a test light so you know you have power with the key off ok,it comes direct from the battery, if yes then check the three pin connector (i think it has three pins) one will have power with the key on and nothing on it with the key off i believe the outer one .if you have power there then you know it is either your regulator or your altenator.and if you have no power there start tracing those wires from the altenator backwards because its open.
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RE: 97 CHARGING VOLTAGE - 10/25/2005 8:59:03 PM
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goodnused
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HockeyMan.. I will double check all that you suggested. I went through the whole harness, both Ohms and volts. I have added an article that I found on possible similar issues. Just education for readers. Also...I am sure you are a fine Technician Hockey... I only implied a ford electric tech..because sometimes they get some inside scoop from the ford training centers. Thank you again. Goodn
“When the engine is started, a 'wake-up/turn-on' signal is sent to the regulator. Traditionally, this circuit is the ground side of the charging system bulb in the instrument cluster. When the regulator recognizes this voltage, it powers up the field and the charging process begins as the alternator rotates. The regulator then uses this same circuit to ground if it determines the system is not working correctly.”
Most technicians consider a charging system failure one of the easier problems to diagnose. Drive the vehicle in, check alternator output, verify the circuits and wiring are OK, and in most cases, replace a defective alternator. What could be simpler than that? After all, some systems only have two wires: one to B+, the other to the charging light circuit in the dash. So, if it's this simple, how can an alternator work fine on a test bench and be totally dead on the vehicle?
Alternators produce current by rotating a magnetic field across several windings, which produces an AC current. This current is directed though a series of diodes, which change it into DC current. The regulator controls output based on the electrical demand of the vehicle and battery. No rocket science here.
The regulator has another job and that's where the problem often occurs. When the engine is started, a "wake-up/turn-on" signal is sent to the regulator. Traditionally, this circuit is the ground side of the charging system bulb in the instrument cluster. When the regulator recognizes this voltage, it powers up the field and the charging process begins as the alternator rotates. The regulator then uses this same circuit to ground if it determines the system is not working correctly. Changes in how this "turn-on" circuit is controlled causes problems for many vehicles. Instead of ordinary bulbs, many instrument clusters now use a low current LED. Other clusters are now controlled by the electronic control module (ECM), which sends the "wake-up" signal to the alternator. The function of the circuit is the same, but the newer designs use a very low amperage flow, and in many cases, reduced voltage, as low as 5 volts. Neither of these signals will illuminate a conventional test light and must be checked with a digital volt/ohm meter (DVOM). A few systems will not send out the "wake-up" signal until the engine is running!
This brings us back to the original problem. Some voltage regulators are not sensitive enough to recognize the low amperage, low voltage signal sent to them. This is why they never "wake up" the alternator on the vehicle, but when energized by a 12-volt source on a test bench, they work perfectly. The solution is to use an alternator with the correct regulator for the application. Charging systems are still simple to diagnose; just watch out for a few twists in the road!
Hockey... I am beginning to wonder if the alternator had the wrong Voltage regulator? Just guessing at this point. Thanks Again...Goodn....I will try to post the answer to all this mystery after it is repaired and working?
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I have been thinking about buying 10 miles of A/C 110 volt cord...where I can drive the truck around with a battery charger hooked up all the time. Let me guess? "THIS MUST BE ONE OF THOSE BETTER IDEAS?"