I have a 2006 f350. I have had problems with the batteries dying so i got them checked and the alternator. Alternator was bad so replaced it. Still the batteries were not being charged. Replaced the alternator again still the same results. Dont know what the problem could be. Ive read about possibility of blown fuses particularly over drive fuse. Any ideas?

 

Is your alternator having 1 thick cable and a plug with 2 small wires?
There is not much to it as the regulator is build-in into the alternator. If one of the small wire is feeding 12V with ignition on, the good alternator has to supply the power via the thick cable. The second small wire goes to the control light.
Welcome to the forum.

 

it is installed correctly there is just no charge going to the batteries.

 

Than take the alternator back for bench test.
What alternator is it? I had a rebuild one from NAPA, who was acting from day 2, but was passing bench test, till it died 4 months later.

 

had o'reilleys check it and they said it was good.

 

original alternator was tested as only putting out 12volts so we changed it. New one didnt work so changed it again. This tested as good. Trucks starts and runs for a few minutes then the gauges stop working and the lights flicker and the batteries die. I dont know what to think about it. Cant afford to go to the dealers so have got to try and find the problem myself.

 

I would take it to electrical auto shop for proper testing.
If the 1+1 does not equal 2, that something is not added right.
Than your description about battery voltage dropping makes me wonder. Understanding that you have dual batteries, the truck should ran for at least 2 hr before the batteries die.
You might have a current draw that is killing the system.

 

do you have any idea what could cause a current draw though? I am wondering if it could be a blown fuse and that the alternator is not charging the batteries because of that

 

Tracking unexpected current draws on vehicle can be a nightmare. Than 2 batteries at 100amp-h each (?) discharging in few minutes makes tens if not hundreds of amps discharging current. Something should smoke?
I would hook up voltmeter to the batteries and observe the voltage drop when you turn ignition on without starting the engine. Than you can start pulling fuses.

 

I'm not sure I agree with the phantom load theory. Once the truck is running the alternator should provide enough power for it to sit there and idle without the gauges crapping out and the truck dying. Generally once the truck starts you should be running off the alternator...you should almost be able to take the battery out of the truck while it was running.

Making the assumption that the new alternator is good, and I have to because the OP says it was tested, then I would look at the connection between the alternator and the battery. This could also be a major ground problem as well.

What volt reading do you have across the battery terminals at the following times:

1) Before you start the truck
2) After you start the truck with it running
3) With the truck running but with it revved up a bit (maybe 2.5k RPM or so)

There aren't many parts between the alternator and the battery but a crappy high-resistance hot connection or ground can cause a lot of these issues.

---Aaron

 

Yep deffinately good advise being given here... If you dont have the cash for a pro to look at it. Time to get really familure with how to operate a multimeter...

If I were in your shoes, I would pop onto the Youtube, and type into the search, how to use a multimeter, and how to troubleshoot dead batteries, and sooo on and sooo forth. You can get great info from the youtube.... Good luck

 

All of the previous advice is great.

First, before any checking make sure you have a good multimeter. I prefer digital, but an analog will work as well.

I'd add checking the output at the back of the alternator, insuring all the plugs and cables attached to the alternator are in good working order and have good continuity THROUGH the connector. Back probe through the connector to the other end of it and wiggle/pull/ shake it to see if the continuity changes.

Charge and load test the battery/batteries. If a battery is beginning to go out sometimes there will be a short that will cause a drain or other gremlins at random times.

Check all battery cables and connectors. Don't assume anything! Put eyes on it and test it with a meter.

I assume you've checked BSOC (battery state of charge) before starting and after a drive/run? If it's intermittent I'd hook up a multimeter to the battery and take a long drive. See what the voltage at the battery is doing at all times. If nothing funky happens then, then connect the meter to the alternator end and check it's output while driving.

What's the instrument cluster doing?

There is a possibility of a larger than usual parasitic drain when the vehicle is off. I've seen instances (mostly gm and dodge) where the computer has kept on the courtesy function for much longer than normal and will drain the battery significantly especially in colder weather. There should be a chart somewhere with the parasitic drain numbers.

Most issues are quite simple and in my somewhat educated guess, rebuilt alternators are often not the best quality. We stopped using off the shelf ones for our work trucks at my job and have a well known local company refurbish them for us and they've lasted as long as the oe ones did. I find rebuilt ones from the big stores have half the life of the oe ones.

Just my 2 cents. Good luck

 

I would highlight it again, that we are talking about discharging dual batteries in few minutes. This is more than a welding current. Without hooking up any meter, I would turn ignition on and without starting the engine look for a smoke or any other signs of overheating.
Would help to know the engine?

 

Re reading through Bluzz's posts: it sounds like a bad battery cable or ground strap. That could've also killed off the alternator (to much amperage draw combined with diodes blowing due to open circuit). Had a Hay wagon that smoked a few alternators with a bad ground strap until I looked at it and found that all the ground straps had been chewed on by marmots. If you don't believe me Mineral King - Climber.Org Driving Directions They sell chicken wire in the local shop to wrap your car in while you hike.

Not sure how the batteries are wired for your truck, but I ran across an old pickup, I think it was a chevy, where the batteries were on opposite sides of the bay and the one positive was ran underneath the engine. The sheathing had worn through on the cross member and shorted to the frame.

I heard this recently so don't think I'm insinuating anyone doesn't or does know this so don't take offense. For GODS SAKE! don't take off the battery cables to see if the alternator is putting out. Alternators don't like this and it'll blow the diodes in them.

 

You're assuming his batteries have a good charge in the first place. Which we don't know. If the batteries are close to dead he may be able to get the truck started (he may even be jump starting it, he doesn't say), but it isn't going to run for long. The 6.0L requires a pretty substantial current to run. I measured mine once and I'm thinking I was seeing 40-60 amps out the main power cable while the truck was idling.

First thing is to get the batteries charged. That's at least overnight with a good quality reliable battery charger. Then see if the truck will run. You want to see battery voltage on the A wire and somewhere around 8-9 volts on the I wire. Those are the two wires at the small plug. If you don't have that, the alternator will not charge.

The A wire is Orange with a Light Blue stripe. The I wire is Light Green with a Red stripe. Be aware that there will not be voltage on the I wire until the glow plug timer expires. This can be up to 2 minutes after you start the truck, depending on temperature.

If you have the proper voltages at the connector, then check the alternator output wire. You should see 13-15 volts. Also check all battery, body, frame and engine grounds and the battery terminals for corrosion.