I've got an '03 F350 PSD that seems to have a charging problem. Right after I bought the truck it would turn the ABS light on first thing in the morning. Once the RPM's came up it would go off but I took it into the dealer anyways. They said it was a dead alternator and replaced it which fixed the problem. That was about a year ago. Right after I picked it up I checked the charge voltage with a multi-meter and it was usually 12.6-13v at most but since it was just replaced I figured it was normal for these trucks.
After recently experiencing an almost dead battery, and not wanting to risk that in winter, I replaced them both with brand new Energizer ones from walmart that read 12.6 and 12.7 no load. Even with new batteries, when I start the truck It will drop to about 11.5V and slowly creep back up but doesn't go past 13V even with raised RPM's. It seems to crank fine but is this normal?
It's too snowy here now to drive my summer car so I can't really be without the truck to pull the alternator to have it tested and I'd just replace it but all the one's I'm seeing online seem to be over $400. I heard that due to the massive drain from the glow plugs and starter and whatnot that it takes a while for all that to shut off and the voltage to increase again. How long?
I've searched but not really found any exact answers for the problem, I don't have a spare alternator to try and I'd rather not spend the money if I don't have to this close to christmas. I cleaned up both sets of posts when I put the new batteries in(they were pretty coroded) Any suggestions?
Have to say I agree with your concern. You could, for instance, have a burned out diode in the alternator that would permit it to continue functioning, but with reduced output. Then each time you drive a short distance the batteries wouldn't fully recharge.
Frankly, if you have snow on the ground, I'd find a way to get the alternator in for testing even though its inconvenient.
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2005 F350 V10 6spd dually, 15K receiver. No 4WD, no LS, no A/C, no special cab - just a lean mean towing machine!
Ours never does on our either of our 2004 6.0 PSDs. They are always in the low 13s. I replaced the one, because it was showing around 11.5 while running. Brand new it was still only charging about 13.3 Not sure if it has to do with the dual batteries or what. But it's been going fine for a while like that. The truck runs a plow, and it has plenty of juice for that, and starting on cold days.
Maybe the most convenient thing to do would be to write down your battery voltages and take a few more readings every few days. If the voltage doesn't drop at all over a few weeks, then benspeedbarn is probably right and its normal...
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2005 F350 V10 6spd dually, 15K receiver. No 4WD, no LS, no A/C, no special cab - just a lean mean towing machine!
It's generally thought that the glow plugs stay on for at least 2 minutes after starting. In cold weather, I think it might even be longer than that.
The alternator is turned on by the PCM in these trucks, and it does not turn the alternator on until the glow plugs have turned off. This is to protect your alternator from the very high current draw of the glow plugs.
I think I would make sure the truck had been running for a safe time period, lets say 10 minutes to be generous, before you check the voltage output.
Lastly, are you sure you only have 1 alternator? Two alternators is a common option.
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2006 F250 XLT SCLB FX4 4x4 6.0L Auto,Magnaflow Turbo Back,RhinoLiner,Retrax Cover,Cab Lights Retro-fit,Overhead Console Retro-fit,Bilsteins,Harpooned,C-Betrs,Fumoto.Fleetwood Pioneer,23'x5,200#
I will try checking over a period of a few days and I'll make sure the truck has been on for atleast 10 minutes. I install remote starters for a living so I know that the plugs do stay on for a much longer time then the light and we usually go by the 2 minute asumption. I'll also check for a second alternator although I don't know how I would have missed one but the truck was a plow truck before so it's possible.
How hard is it to add a second alternator? I do alot of single track riding out in the middle of nowhere so I have a lot of attitional off road lights for when I'm leaving a trail late and I have a descent sized stereo in the truck. I'm also a fan of having something overbuilt so it won't leave me stranded so I'd just prefer the peace of mind of a "backup" alternator if one were to fail.
The standard single alternator is up high, on the passenger side, and you definitely will find that one. The second, if it has it, will be down low on the same side, and you have to look for it.
I've never heard of anyone adding a second, so I don't know what it would take. But I'm sure you would have to have the dealer program the truck to operate it.
I've never quite understood how they program the logic for the second alternator. It seems like it just sits there doing nothing, until the current draw is more than the primary alternator can handle, and then it kicks in. I've heard of guys still having dead batteries, just because the primary died and the secondary still didn't kick in. Doesn't make a lot of sense to me, but I am not sorry that I don't have the second one.
I don't think a secondary is any protection against a failed primary. But the secondary is good for tow trucks or ambulances where they need a lot of output.
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Folks call me Bill.
Please pass the GREEN nozzle.
2006 F250 XLT SCLB FX4 4x4 6.0L Auto,Magnaflow Turbo Back,RhinoLiner,Retrax Cover,Cab Lights Retro-fit,Overhead Console Retro-fit,Bilsteins,Harpooned,C-Betrs,Fumoto.Fleetwood Pioneer,23'x5,200#
I've never quite understood how they program the logic for the second alternator. It seems like it just sits there doing nothing, until the current draw is more than the primary alternator can handle, and then it kicks in.
You are on the right track with your idea. The basic job of an alternator is to maintain system voltage at a specific level. It does this by turning on/off at high frequency and the duty cycle controls the amount of charging current. This also causes the voltage to constantly cycle above and below the target charging voltage. In a dual alternator application, one alternator will have a slightly higher voltage set point then the other due to manufacturing tolerances. The alternator with the higher set point will be working harder then the other alternator. How much harder it works will be dependent on how much overlap there is in the range of voltage each alternator has around the target. If the manufacturer has really tight voltage tolerances then the second alternator will be contributing something most the time. If the tolerances are not very tight then you could end up with one alternator just along for the ride until electrical loads exceed charging capacity of the first.
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