Guys -
I have been experiencing issues with my 02 Expedition, 5.4 EFI - the battery is only a few months old, and it only starts the truck after a day or maybe two if I park it, but definitely wouldn't start after about three days. I did a voltage/leak test, and it seems like it wasn't drawing much (.56amp - at least I didn't think that was much...?) at rest, but lately I have been disconnecting the Edge power programmer at night and that saves about .25amp from that. I tested the battery after running a bit and it says 12.5 volts. When running, the battery shows about 13.9 volts. I checked and cleaned the battery terminals and cables to the starter. The ground strap to the firewall was in good shape. The starter itself is strong. The one test that looks like it failed was the alternator A terminal to the pos battery terminal - the manual says the voltage drop should be about .25 volt, and mine was almost 2V drop. The resistance was fine to the mega fuse from terminal F on the alt, and there was not internal short.

So can that amount of drop on the voltage regulator can affect the battery charge? One other thing that struck me was a surge right after starting, when the battery was charging at about 16 volts, but then it settled after about a minute to the 13.9 or so I mentioned before. Is the reguilator 'on its way out?'

I am looking at replacing the regulator, seems to be about a $50 part vs. $165 for a new alternator (although I only looked at one online store, so far). Do folks normally go for a new alternator, assuming if something (heat, age, whatever) affected the regulator, the alternator windings, etc can't be too far behind??
thanks for any thoughts you can share!

 

The "A" terminal is what the alternator regulator uses to monitor the system voltage level. The regulator looks at the "A" terminal, and then tells the alternator how much to charge. This would affect your voltage as the engine was running(how much it charges). You said you are running about 13.9v, which is higher than 12.5, so that means you are charging the battery.

.56amp is too much drain. It varies from vehicle to vehicle, but around .07amp is where you want to be. Notice the 0 in .07amp. Your drain is way too high.

Does this power programmer have to be on all the time? Maybe you should hook it to a hot in run power source if it has a memory inside it.

Check for any other stuff that has been added. Even if you save .25amp, thats only half and it will still be too high.

 

Thanks for the info - i guess I thought the .56amp was a decent number, but i can see that it is high if a reasonable number is a draw of .07amp. Wow - so there is a GEM module that was also drawing about .14amp, but there are a lot of other things on that circuit...guess i go hunting there? what's normal for that circuit, if anyone is aware (i don't have my fuse number or owner's manual here to detail what's on it, will do when i get home from work).
thanks for the reply!
tom

 

p.s. I didn't answer you about the Edge Power Programmer - it plugs into the OBD port by driver's right knee...I am hesitant to rewire that! I just unplug the thing each night now. But it's clear I need to look for other voltage drain that shouldn't be there.

On the voltage regulator - would you be concerned about an almost 2V drop fromt he alt terminal A vs the positive battery terminal? The Haynes (yeah, that's all I got at the moment to troubleshoot with) seemed pretty specific that it ought to be .25V or less drop. That was the only thing (other than the .56amp draw) that seems to be an issue.

thanks again! Tom

 

2v drop is a little high. But it seems you have multiple problems, so I would put that on the back burner for a little bit, since it seems to be charging ok like it is.

I would concentrate on the drain. On these newer vehicles they have a "battery saver" relay that works with the GEM, and also controls a "Accessory delay" relay. Before you check for a drain, you need to make sure this thing has timed out. You know how you can play the radio and roll the windows up and down for a period of time after the key is out? That's what I am talking about. I am not sure exactly how yours works, but some of the vehicles I have turns this off once the door is opened.

Also make sure when you are doing your tests, that all the doors are closed(domelights off) and if you have a underhood light, you will have to unplug that while you are doing your tests. Anything like that will foul your drain tests up.

Any added amplifiers or other stuff need to be checked and disconnected also to see if they are the source of the drain.

If all else fails, disconnect all the wires on the alternator, and see if the drain goes away. Sometimes components can fail inside the alternator and they will cause a drain.

 

Thanks, Dave - Great information and some other things I can check on. I seem to remember that my radio goes off when I turn the key off, so if I do have an accessory delay relay, it may have failed. I did the voltage leak test with the doors closed and hood light pulled, so I think my numbers so far are good, I will just need to look at that one circuit with .14amp, plus a couple of others with justabout .02amp each...which may be the ones that are normal.
Thanks again! Tom

 

Well, a day and a half after having to jump the truck to get home from work, it seems to be doing better. All i did that night was remove all the cables from the starter and battery terminals and clean them and the terminals really well. It started right up tonight after parking it for 24 hrs, something it didn't do after only 9 hours the day prior. I'll let it go a couple days and try again Saturday and see how that goes. That's the first chance that I'll have to get back to the voltage leak issue anyway, so at least it'll tell me (assuming it again starts right up) that just cleaning what looked like already very clean terminals and cables makes a difference.

 

m3buzz,
I am having a simalar problem. Can you tell me how you did your voltage leak down test?


Thanks,

 

Here's a easy way to check for a drain on the battery.

 

Thanks for the fast reply. I'll try that when i get home.

I just had my battery tested and it's fully charged and good. Put a new alternator on the 5days ago. I'll go around and clean and check all the connections from the battery to the starter.

thanks again

 

I did my test with the voltmeter to get a handle on just how much of a drain I had and from which circuits. I still get a steady .31amp drain (unplugging the power programmer every night, what a pain, but decreases draw from .56A). The voltage regulator test still shows more of a voltage drop than what the manual says it should. And of course, the battery was not strong enough to turn the starter on Saturday. Seems to hold a charge for a day max now. I think the battery is dying. I am beginning to suspect a compound problem including a leak and a regulator issue...but it's all hit and miss...and frustrating. I hate to go throwing money at it by buying parts until i can very clearly find the bad part(s).

The circuit with the most change when the fuse is pulled is the 5A fuse 15, which the manual says is for: Stop Lamp Switch, (Speed Control, Brake, Shift Interlock, ABS, PCM Module Inputs, Air Suspension Module, Autolock), GEM Module.

I don't have an air suspension, and don't know what the GEM module is, and have had no issues with brakes or brake lights. ABS works, as does autolock once i start moving. Has anyone seen this circuit draw .20A steadily before? Assuming that's not normal, per Dave's original reply, any ideas where to look for the 'always on' villian?
Thanks!

 

0.2 amps at 12 volts is 2.4 watts... that's enough power for something to get noticeably warm, unless it's heatsunk to something big. Maybe you could wait until the truck has cooled down overnight, then feel the various suspect modules, or use a laser thermometer (or infrared camera if available... some Sony camcorders had a notorious see-through-clothes infrared mode).

And, put it on a charger overnight until the problem is solved. That'll help charge the battery fully, and keep it from being drawn down overnight. Unless you're driving all day, the battery may not be fully recharged. (A normal start may only use about 1 amp-hour of energy, according to a post by "chuck s" at FTE. And that's Plausible, since I've been able to drive my truck home after leaving the headlights on all day, just by charging at an amp or two for an hour with a lab power supply.)

 

Good idea, Angus - i have a laser thermometer, and will check that out - hadn't thought at all about heat generation from whatever it is that has been 'always on' and draining the battery. As for charging, unfortuntely, the truck sits outside, not in a garage, and I hesitate to string a cord to a charger that I'd have to tuck under the hood. So long as it seems to charge enough during my 20-minute drive to and from work to get me back and forth, I only charge on weekends during the day - which is when i tend to use the car less. Battery voltage usually tests ok at 12.6 or so, so i think it is still healthy through all of this.

Thanks again for another debugging idea