Slow Cranking..head lights flash randomly during cranking

[JBlomenberg]

Yet another slow crank thread, but I think I do have a battery / electrical issue.



I have a 2004. 5 5. 9, 2500 4x4. About two months ago I changed the front shocks at around 120k miles. Changing the drivers side meant I had to take the battery out.



In doing so, I did notice some corrosion on the negative terminals of both batteries, so cleaned that up. I put it all back together, and immediately noticed that the truck was slow to crank, just like with a dead battery. I thought that was odd, since prior to cleaning the terminals I didn't have any trouble.



I shrugged it off and decided to keep an eye on it. After two months I have the following symptoms:



Normal cranking after a long drive when the battery can charge up.

Slow Cranking after a 4 hours without running (such as starting at my lunch break at work)

Very Slow Cranking after 8+ hours without running (such as overnight)



That makes me pretty certain I have bad batteries. The only concern that I have at this point, is that my head lights will occasionally flash randomly during cranking, when it is really struggling. Why I find that odd is that I don't have day-time running lamps, and the head light switch is in the "off" position.



I'm thinking I may have a short someplace, which is dranining the batteries while it sits. Any thoughts? I'd like to diagnose that before replacing the batteries, so I don't immediately drain them too.

 

[Prairie Dog]

If the batts are original then it's probably time.
I would clean up all the ground points such as the screws that go into the quarter panels. There are a number of very important ground connections at these bolts including the ECM's.
The pic shows two of these Grnds at 9:00 & 3:00 but there are at least 3 or 4 more located on each side of the eng compartment.

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[JBlomenberg]

Yep, batteries are orignal, and the green glow "status indicator" is very feint. Looks like I have a good weekend project ahead of me.



I'll check all the grounds really good to make sure something else hasn't gone south there too.

 

[Prairie Dog]

Good luck and FWIW, the green glow thingy is only for that one cell so it doesn't tell you much really.

 

[cerberusiam]

Load tesitng the batteries is the only way to tell if they are good, forget the little green dot, it lies.



If they orginals they have exceeded they life expectancy by 2X, its replacment time.

 

[JBlomenberg]

Well, bit the bullet and bought a couple of new batteries. I've had good luck with Autozone Duralast Gold batteries in past vehicles, so went with them again. $300 later, and about 45 minutes and I'm back on the road.



I did find one thing clearly defective in my system. The negative post on the passenger side battery had more or less come free from the rest of the battery. When I losened the battery cable and pulled it off, the post came up and out with it about 1/2". A few taps from a ball peen hammer freed the two up.



I cleaned all of the grounds I could find with a wire brush. Nothing obvious, but easier to do now than later. I didn't take the cables off of the block, as I didn't want to risk screwing something else up down there if the wrech were to slip (had that happen before).



Buttoned it all up, and then the moment of truth. She started right up (as if there was a doubt)! Cranking speed was noticeably faster, and it fired after about the 3rd revolution, which is what it did previously. I'm going to keep an eye on things to make sure I don't have short in the system someplace though.



Anyone know if putting a multimeter across the terminals is a good way to determine parasitic draw when the key is off? The old batteries had a couple miliamps when the key was off. Wasn't sure if that was normal for things like the clock on the radio, etc.

 

[cerberusiam]

There is a constant parasitic draw even with the ignition off. It keeps the clock and internal electronics powered and synched. The IOD fuse is repsonsible for those components. A battery minder during long storage is about the best solution.

 

[BGlidewell]

In my experience a clamp-on ammeter is the best way to measure battery drain/draw.

 

[sag2]

In my experience a clamp-on ammeter is the best way to measure battery drain/draw.

Usually not accurate enough to measure Ignition off Draw. On the newer trucks the good reading is 60ma or less. Not many clamp on meters are that good.

 

[BGlidewell]

Usually not accurate enough to measure Ignition off Draw. On the newer trucks the good reading is 60ma or less. Not many clamp on meters are that good.

mine is, i stay away from toys when tools are required