Nope , didn't scare me off still pulling my hair out. Okay the alt checked good it pulled the batteries down . checked alt again replaced a trailer tow battery charge fuse just in case. Got a jump started right up then pulled batteries down again, check alt again still good.I know everyone said it should run without batteries connected but I have had a truck that would not run if the battery was dead. it just stalled when I was driving, changed the battery no probelms ever again.Anyway if anyone has more ideas please let me know.. thanks.

 

Dealing with electrical issues has historically been a pain-in-the-a$$ because you can't "see" what's going on inside a wire in order to determine current flow, etc.

With a $60 Sears Craftsman 400 amp AC/DC clamp meter (82369) you just close/trigger the measuring loop around an alternator wire to directly and dynamically read the amperage in a wire, without removing any vehicle components.

As a consequence it takes only seconds to determine the exact current an alternator is putting out, or to determine the existence and amount of a normal/ parasitic load on a battery, etc., whether the engine is starting, running or off.

Its a great cost-effective diagnostic tool that takes the guesswork out of automotive electrical issues, for any one who might be interested.

 

Ha! You posted while I was writing.

I'd use a dc clamp meter to measure the current draw off the battery and the alternator, initially with the engine off, and then with it on. With those readings your next steps should be readily apparent.


For instance, your alternator may be just fine when tested at the store, but if the exciter coil isn't receiving 12v in your vehicle because of a bum ignition switch, the alternator won't work and the batteries soon die.

 

Does anybody know if they are able to test the regulator when the bench test an alt. I have never had one done so im not sure how its tested.

 

Here's a pretty simple explanation to review:Charging system diagnostics: battery, alternator, and related systems

Also, re read through the previous postings. There's lots of good info that can point you in the right direction.

The best and foremost thing is to make sure the basics are good. Batteries, cables connections. If those are good you have to go further in Depth. Check out those and repost with the results and we can further help you.

I'm an electric forklift tech and have many years of experience with batteries and am often called to look at the charging systems in a multitude of different IC (internal combustion) charging systems.

One thing you need in any troubleshooting scenario regardless of what you're working on is a "Theory of Operation". If you know how the system works it's much easier to diagnose. And yes, something such as a charging system can vary greatly between manufacturers, especially with newer tech. 10 to 15 years ago not so much. But now some manufacturers have computer controlled charging and other devices that integrate into the charging system. Especially if the vehicle operates with specialty electronics.

But I'm going off on a tangent here. Get a good basis of the Theory of Operation and with that check the basics and you'll have a good foundation to diagnose and fix the issue.

 

Oh, and yes the regulator as long as it's internal is tested during a bench test of an alt. You can bring in external regs and get them tested as well, but I haven't ran across an external regulator on a car/truck since the 80's.

The problem with bench testing any component is that it doesn't exactly replicate real world conditions, ie extreme cold/hot and vibrations. Often in my field the problems only happen when the truck is under extreme load/duress and it's often hard to replicate a tough 8hr work day on a piece of equipment when you're there for only a few hours. You end doing some things not really recommended to try and replicate it. Like putting it against the curb or wall and putting your foot to the floor and seeing what smokes. haha! I try not to smile while doing this as it disturbs my customers.

 

Nice!

 

Ha, luv it! Just don't try it with your Superduty...


I'm reminded that my son has a new Mustang with a manual that he had to learn to drive. As he was learning to apply gas while letting out the clutch he would occasionally kill the engine even though it has over 300 hp and is relatively light.


He couldn't believe my '350 would go over a curb at idle.......

 

Yeah, that kind of testing is a lot easier to do on electric and ic lifts than big trucks. When I used to work for the army we'd "road test" the big trucks out on the trail routes the army'd use for off road training. We'd flog the **it out of those things! I mean it was creul, but on the flipside if you didn't ruggedly test them and it failed in the field it could be someones life or your butt in jail (for falsifying a repair).

Wow! Lucky kid to have a new 'stang w/300hp. My first car was a poor old mitsubishi truck. Great truck, no where near that much HP. I could've done a lot of damage in HS with a car like that.

 

We still don't know if the batteries were charged and load tested. 110amp on my 6.0

 

PA-Mark,

Don't know what I did to upset you and get you to post personal attacks. I posted in this thread 1 1/2 hours after the OPs original post trying to provide some assistance and I did not pick one 'post' to reply to to make myself look smart.


---Aaron

 

What do you mean by it pulled the batteries down? 'Pulling something down' in electronics means that an item drags the voltage of something else down to its level. Does your voltage actually drop when the alternator is running? If so that is a definite alternator issue. The alternator should always pull 'up' the battery voltage and not the other way around.

As to stalling while driving when a battery is dead that will definitely happen if the loads exceed the output of the alternator. This is why I made so much mention of the defroster running, headlights, etc in previous posts.

When you have a bunch of electrical items running and your battery is bad/discharged and you pull up to a traffic light the alternator is not putting out enough charge current to supply the necessary current. In normal cases the battery will make up the difference until you get going again but if the battery is dead the truck will simply die. It can also happen when underway when a major load is applied that exceeds the ability of the alternator to supply.

A great example is the new rapid-heat. That literally pulls hundreds of amps when running and there is simply no way the truck can generate enough current to power that, plus headlights, stereo, PCM etc when driving (except with possibly the dual alternator system and even that is a stretch).

The point that I was trying to make earlier was that if the truck starts under its own power and was simply sitting there and idling with nothing on (or very few items on) it should be good to go and run almost forever. If you have a lot of loads running, such as an ambulance would, then you need a dual alt system and/or an increased idle RPM to provide additional current so as not to drain the batt when idling. A stock truck should not require this or Ford drastically undersized the alt for the truck.

If you have to jump start this baby to get it going, and assuming that the 'pulled down' statement above was a misstatement, then I would look hard at the batteries. If your batteries are starting out discharged then that leaves no reserve at all for moments when the truck has to momentarily pull extra juice from the battery to make up for a temporary increase in load or decrease in charge current. They are probably not accepting a charge anymore so as soon as that scenario happens the truck dies.

Best of luck.

---Aaron

 

I have had a bad battery kill an engine, even though the alternator was OK. The battery had an internal short. If this is the case, look for a VERY warm battery.

 

Until you charge those batteries with a charger, and then load test them, everyone is just pissing in the wind.

And I'll say one more time, you are risking very expensive damage to that 6.0 if you keep screwing around with weak batteries.

 

Ok well i publicly appologise to you here... BUT.... here is where i had a problem...

I was not addressing the OP problem. I was addressing another post that said something to the order of "it doesnt matter how dead the batt is" Well that post was inacurate because it does matter, Then you get on and spred even more crazy bad info with your post while quoting my post... So thats how we ended up here. Again, all input is, and should be welcomed, but when you grab somebodys post then contradict it when you dont know what your talking about, partly because you didnt pay attention to "the context" well you get what you get.

If you wish to continue this discution further, PM me. No need to muddy up the boards here.

But again, I apologise to you Sir, for any hurt feelings,

Mark