2005 E-150 Tractor Parts Hauler, Drains the Battery

[Indiana Ken]

My van has a 4.6 liter V-8 with some 300K miles on it. Lately the battery will become discharged after sitting for several days. I measured a 450 +/- Milliamp drain. Looking for ideas on what to look at first. The alternator maintains 14.7 +/- volts at idle. Can the alternator be the leak path and still charge okay?

 

[guido]

Indiana Ken,

The alternator could do that, but it is not usually at fault. If your battery is not a sealed top, it may be that the top is dirty, it will them draw current while the vehicle is off.

There should not be any voltage readings between the + side of the battery post and the top of the battery.
If you get a voltage reading, then you need to clean the battery top,


Guido.

 

[guido]

Indiana Ken,

Is it an open cell battery no Check for voltage leak on the battery top.

From the plus post to the battery to. Check all over the top. You should not get any voltage reading.

If you do it may be the course of your problem,


Guido.

 

[RJKeith]

While if the dirt on the top of the battery is conductive, what you suggest can certainly happen, my guess is that he is not measuring that, and he is getting his 450 milliamps from something else.

 

[KCTractors]

I was fighting the same thing with a 06 Ford Explorer. Was told the battery was bad, replaced the battery twice with new batteries. Had the alternator tested, said it was fine. Was told the rear window wiper was the fault, disconnected the wiper plug, no change battery dead. Finally after a year and half the alternator died. Replaced the alternator with a new one and it was the end of the problem and I have everything connected back as it was.

 

[Geo-TH,In]

Take the guess work of finding parasitic drains. Buy a clamp on DC ammeter.

 

[Steve@Advance]

That is a substantial drain. You want to see .050 amp (50 milliamps) or less.

There is a process to determine the final amp draw. All modern computerized vehicles have a 'time out' feature, or once the final battery connection is made, electrical events are initiated. Things start timing out, like dome lights, headlights, modules, etc. There may be a heavy amp draw during this process which may over amp a digital amp meter.

The safest and most reliable method is to remove the negative battery cable, connect the cable back to the battery post with a jumper wire. Then connect each lead of the amp meter between the cable and the battery post, along with the jumper wire. Connect it so the jumper can be removed without breaking the amp meter connection. Make sure all accessories are off, doors closed, hood light disabled, anything that can cause a battery draw is off or unplugged.

Allow the system to sit undisturbed for at least 15 minutes, then remove the jumper, allowing the current flow to pass through the amp meter leads. Be sure not to break the connection. If any doubt, reconnect the jumper and let go through the time out again.

Then start pulling fuses and relays at the under-hood fuse box, one at a time replacing each as you go. When you see the amps drop, that will be the suspect circuit. BUT! Opening and closing the circuit can restart the time out process, which can overamp the meter, be careful! Some meters are internally protected, some are not.

If none of the under-hood fuses or relays drop the load, there are other fuse blocks inside the vehicle. To access them the door switches will have to be held closed or somehow gain access without having a door open.

Another common source of battery drain is added alarm systems, remote start systems, and aftermarket sound systems. They are common failure points and sources of improper wiring practices.

Back to the alternator question, yes it can cause a draw and still work. Try unplugging and disconnecting it. That would be a good place to start. But it can be more complex than that, some alternators are controlled by the ECM. Just because unplugging it dropped the load doesn't mean the alternator is bad. Let's hope not to go there!

And then there is the battery itself. Do you have another known good battery to swap out? See if the problem goes with the battery.

 

[4play]

Interesting, I usually read all comments before posting, not this time. I wrote a 2 paragraph detailed answer and posted it. Then reading the post directly above mine, I realized Steve@Advance has already said everything I wrote. He must be in the same profession I am.

Anyway, here's some testimonial advice, most of the time I find draws, it's aftermarket accessories, lighting, stereo, brake controllers, doodads etc. I've wasted many hours searching every fuse and circuit only to spend a couple minutes unplugging the alternator.

And then, I don't know how often you use the van, or how much time and money you want to invest but if you get to a certain point then consider a manual battery disconnect. It's not law, but disconnects should be on the Neg post, most that I see were put on the positive.

This post was edited by 4play on 12/14/2023 at 10:30 pm.

 

[JF in MI]

Yes, a bad diode in an alternator can cause your symptoms and still charge and possibly test OK. Don't need any special tools to test, just a 12 volt test light. Disconnect one of the battery terminals and put the test light between the post and terminal (it should light up). Then disconnect the main output wire off the alternator. If the light goes out (or goes real dim) that's the issue. If not try pulling fuses one at a time until it goes out. I had a diode come loose off it's mount and short out in the alternator frame. Melted the main fusible link shutting down the entire electrical system.

 

[Jeff NWOH]

You don,t necessarily have to pull fuses to find your draw. Set your voltmeter to millivolts and measure across each fuse. The one(s) that are passing current will show a few millivolts while the ones that are not will show zero. This saves waiting for a system to have to go back to sleep after plugging its fuse back in.

I saw this hack on Youtube from South Main Auto, and it works..

 

[ss55]

Some radios ( and alternators ) can become a constant battery drain as they fail, even when the vehicle is not in use. BTDT on a Chevy pickup radio.

For peace of mind, 2X on a manual battery disconnect, at least until the battery drain is fixed.

 

[Bill(Wis)]

Any lights that are hidden, like glove box, underhood, etc?

 

[Blackhole49]

You don't say how old your battery is or what your definition of several days is. Before I gave it to my son in 21, my 08 Silverado would be sluggish after 2 weeks and not start after 4 once it was 5 years old. It only got about 4k per year. I finally replaced the original battery in 21 before I gave it to my son. In the mean time, I used a smart plug and an inexpensive B&D battery maintainer and ran it for a day every week or 2 when it was sitting. Currently doing the same with my 18.

 

[Frankmn]

I have had a few fords that get a windshield leak that gets the ecm wet under the dash on the drivers side. The ecm then energizes a relay for the heater or the wipers. If anything that shouldnt work with the key off is working, that's the problem.

 

[Bruce(OR)]

How long did you measure that draw? 15 seconds or two minutes? You should see a drop after about 30 seconds. Did you notice that? The ECM wakes up with the power connected and then goes back to sleep 30-60 seconds typically. Your's did what?