Anybody out there have any problems with a slow drain on their batteries?

My truck wouldn't start after sitting for 5 days.

After recharging and starting it up once, I pulled the key, and disconnected the battery harness and checked for current on all the red wires in the harness. Only one drew current. I found the small red wire on the drivers side initially draws 470mA for 1 minute, then draws 22mA. In my experience in mobile audio, 22mA can drain a battery over several days.

Has anyone out there checked their 'dark current' draw? I have chased it all over and checked all the aftermarket add-ons and it comes down to something in the factory dash. Any ideas?

Thanks

 

Seams silly but have you noticed if the lights are turning off when you shut the doors? Even if its not a door switch, for some reason ive got lights that stay on much longer then others on my truck... im still working out all the kinks.
You say you think its in the dash? Have you cheked your relays. Could have 1 locked in the closed position.
notice anything isnt working?

 

Thanks for your reply. No lights on in cab or under hood at all when I connect just the one wire on the driver's side battery cable to the battery. Everything works that I am aware of. Must have doors closed to get lowest current after 1 minute. Have to find my notes to remember which wire in the bundle that draws current.

 

I'm digging through the memory here, but I think that 22mA is less than the 50-75mA Ford said was acceptable after the PCM went to sleep.

Age of the batteries, float voltage, and did you load test them separately?

Motorcraft stock batteries would have about a 130 minute RC at 25 amps, dropped to a 0.5A draw that's what like 200+ days before they drop to 10.5V?

260 RC * .4197 = 108
108 * 25A = 2708 Ah at 1A
So 2708 * 2 = 5417 Ah for 0.5A, or 225 days?

The 6.0 is murder on batteries, I would suspect bad batteries first if a very small 22mA draw is making it not start.

 

I have the same thing on my 07. About 4-5days the cranking gets a little slow. Can't figure it out everything seems to work as it should. What is the test procedure to find the drain?

 

You need a meter that can show amperage being pulled through the positive battery cables. Once you have that, the way I do it is to start pulling fuses 1 by 1 until you don't have any drain. That fuse is the circuit with the drain. Look at a wiring diagram and see what is on that circuit and start unplugging those things until you find it.

Good luck!

 

a one amp draw is nothing..
many cars/trucks from the 70's and 80s.. the computer memory was ON all the time.
remember all wet batteries have an internal resistance and as a battery ages.. the internal resistance goes Down and looses its power faster... but output of battery is lower.

have batteries LOAD TESTED.. only the 100 amp load test has any real meaning.
my opinion.

with 2 batteries... one going bad will kill both...
2 batteries at 650ah each.. is 1300 ah.. that is 1 amp for 1300 hours. plus or minus a bit. so half that and truck should still start.

 

That makes a lot of sense. 22mA is about 1000 times smaller than 25A which is 90 days. I got two new batteries on warranty so I'll hook them up and watch the voltage every day - Thanks

 

It's funny how fast batteries go dead with this engine. I did an 1800 mile road trip the week of the 4th and everything started and ran perfect the whole time. Truck sat for a week or so when we got back, and the batteries were flat dead and wouldn't start the truck. It's been the same exact story the last three sets of batteries; seems like I get one slow start then there's no guarantee it'll start the next time.

Stock alternator? If you have the original 110A unit that's going to be pretty hard on the batteries to start with, plus hard on the FICM. This is some really good reading on a "big 3"-type battery cable upgrade that makes a difference:
https://www.ford-trucks.com/forums/1...tery-life.html The video in the first post is great to watch.
https://www.ford-trucks.com/forums/1...lternator.html
https://www.ford-trucks.com/forums/1...lternator.html