For the last week and a half - 2 weeks Ive been having an electrical issue that seems like a dead battery where the truck wont start if its been sitting. The battery is only about a year old and has been fine up until now. I went and had it tested and it passed with flying colors (mind you once you get it started in the morning its fine all day). Then had to call AAA the next morning because I had no one to jump me...he again tested the battery, starter, and alternator and they all passed with flying colors again. What is weird is if I have to jump it after it has been sitting for awhile, the cables have to be hooked up for 5-10 min before it will start (but the battery has right at 12V already).

I checked all the connections from the battery to the starter, and all the ground cables, loosened up the terminals & retightened them, etc. Im probably going to replace the terminals, and was thinking about doing the big 3/5 ground cable wiring upgrade, but I cant think of anything else to do and I dont want to put another $100 battery in it if its not the problem...I need some ideas please!

 

How was the battery tested ?

A true load test takes some time, as it has to be charged before the load test. Autozone and the likes walk out with the one size fits all tester ( the load test depends on the CCA capacity of the battery ).

What accessories / modifications do you have ?

 

It may not have been a true load test then but I know they wont warranty the battery because it passed there test. Who could do a "true" load test...obviously a new battery would be the easiest solution, but I dont have the $100 to throw at a new one and then have it not be the problem and waste the $100. The CCA of the battery is 700 and they did have to enter that into their little scan tool deal.

Well I have a completely different drivetrain but its been fine for over a year...electrically I have a larger stereo system, and IC pump for the intercooler system, electric brake controller, and a freshly rebuilt alternator.

 

MXR, you do realize that a fully charged 12V battery should show at least 12.6V right??? 12V is at least 1/2 or more discharged, depends on who's chart you're looking at. Technically it should be about 13.2 at full charge but a starting battery won't hold that charge for very long but should settle at least 12.6V.
You said you had a fresh rebuild on the alternator, is that a "rebuilt" or did you have someone rebuild it?
I have an OTC conductance testor as well as a 1000 Amp carbon pile load tester. I use the OTC most of the time because it will give me CCA's as well as AH's and alt. and starter test but frankly I have never had the trust in it as far as true load testing that I have in the CP tester. I know industry standard now is Cond. but I have seen where it doesn't cut the mustard in all cases. My son's Suburban (yea, I know, I raised him right but his wife's family kinda favors GM so don't blame me) went dead with a 770 Wally World battery that was only about 9 mo. old. Fully charged with Smart charger and then tested with OTC each hour for next 3 or 4 hours. Tested fine (faint drop) but then put it to the CP test. It bailed like you couldn't believe. The conductance (OTC) ran $500. so it should do the job, but I just don't trust any Cond. when the going gets complicated. Nuff said.

 

Right, and they'll even try talking to yuh when you get them over 13v. Tried stethoscoping, don't bother, just sounds like bacon.

12.6? I was under the impression that was the old days. Or maybe I'm thinking of 12.8 as a settling point. The OLDER Motocrafts had the highest from what I recall. Not any more and haven't for quite some time. Second thought, yea, 12six does sound accurate now a days.

Had one battery out for awhile. When I needed it, it was @ 11.8. Wasn't sure if that was going to fly, however, she whipped it over no problem. That was to start the truck. I know you can't go much lower than that, -not sure where that line is.

OP, -As these guys have said, -proper load test is a tell all. Doesn't matter if the volts test good or not. A weak cell(s) become evident under load.

 

FWIW I've had a LOT of battery trouble in the last few years. A LOT of the batteries that were made 3 or 4 years ago were real bad about having intermitant connections internally. They'd charge and test perfect and would operate perfectly but suddenly just develop an electrical open like you'd turned off a switch! In one case I was sitting at a red light and the car just stopped like you'd turned off the ignition! Another died for no reason when I was sitting in the car with nothing on except the radio. In both cases, the batteries just started working again after sitting for an hour or more! I replaced both batteries (and four others!) even though the dealer tested them and insisted that they were good. After buying other brand batteries I've had no more problems. MOST of the batteries that I had trouble with were from Discount Auto Parts but one was a less than 1 year old battery installed by the Mitsubishi dealer. There are only a couple of actual battery manufacturers so the problem affected a large number of brands. Like I said most of my trouble with them was a couple of years ago and I switched brands so I don't know if DAP (and the others) ever fixed their problem or not.

 

It sounds like there is a high current drain on the battery. When it sits for sometime, this high current drain is killing the battery. Remove the negative battery terminal, and hook a current meter between the battery post (-) and the negative battery terminal (+). A normal current draw is 40mA - 50mA.
If the current is too high, remove fuses one at a time and watch for the current to decrease. This will identify the circuit(s) that are drawing too much current. Another thing you can do to confirm the high current drain theory is to disconnect the negative battery terminal, and let is sit overnight. When you re-connect the negative battery terminal in the morning, and it starts ok, you will know the problem is a high current drain while sitting, not a problem with the battery, or alternator. However, an alternator can cause a high current drain when sitting, but since you have replaced the alternator and the problem still exists, I don't think the problem is the alternator.

 

Nah Brew, I charge 'em all the time with a Smart Charger and they will go to over 13V without ever changing the temp of the battery at all. The "cross breeds" in the motor home would always go to 13.2-13.3V before it would shut off at "FUL". A true "deep cycle" will go to 13.2V and hold it if it's in good shape. The battery in the truck and car will both go to over 13V before the "FUL" but they won't hold it like a deep cycle. The Motorcraft (one of the best batteries I've ever seen, but NO MORE, since GNB sold to Exide and they went to having JC make their batteries) would always hold a solid 12.8V but I've never seen any other production battery hold more than 12.6V, even when new. The people that buy a Motorcraft now because they got 9 years from their old one (GNB) are in for a shock!
No "frying bacon" with a Smart Charger. They really do have a brain (at least mine does). You only have "the smell of bacon" when you push a battery to 13+V with a fast charger- yep, gonna have warped plates then.
Rule of thumb for a fully charged battery is 2.1V per cell but technically it's 2.17V per cell which comes out to 13.02V. Have no idea how they figure that or control it, but that's been chiseled in granite for a Loooooong time.
Have charged and tested probably thousands of batteries in a long career and Motorcraft (GNB) was virtually unparalleled.

 

So whats the verdict on the battery problem????

 

Still trying to find a place with a true load tester! Can't seem to find one down here. It will charge to 12.7V and hold the charge but still not start, I've seen it over 13 getting jumped and still not start right away. It died on me the other day too which was wierd. I already did a draw test as mentioned and found no draw...it was zero but I may have been on the wrong scale (followed a YouTube video and he showed a draw on the same settings). Also the truck wouldn't start one day even after I left the battery unplugged overnight to rule out a drain on the battery. I'm kinda thinking battery especially hearing your guys experiences, just very strange the way it's acting

 

If I replace it, motorcraft is no longer the way to go, what would be the best battery to buy?

 

Hows the alt doin??? Also check the solenoid if you still cant start it even when its good. The alt is chargin the battery good.. u get at least 13v to 14v when you check it when running. If your battery shows good and it wont start then go somewhere else and look. Wouldnt worry about battery yet,,,, if you got a good battery and it wont start then a new battery wouldnt help. As long as you have at least 12v at battery you should be good,,, hopefully a little over 12.

As far as a good load tester goes walmart had a good load tester. Or at least the last time i went to one. To replace a battery of theirs.

Also if you get it started next time,, disconnect the positive side battery connection and see if truck runs still????

Good luck

 

The best battery is the one you can afford to buy at the time!!!!!!!!!!!!!!!!!

 

Sadly, I don't know how to answer that question. Reason: Johnson Controls makes about 80-85% of the batteries in the U.S. now and because I test my batteries (and have for years) about every 2 months or so, I know what condition the battery is actually in, not just "it starts the truck fine so it must be OK". Frankly, that's utter nonsense. JC makes junk, clear and simple. When I test my batteries the one thing I've noticed with JC is that they don't want to hold voltage. Every JC battery I've had is unable to hold 12.6V by the time it's a year old. Everything works fine, but the battery starts to go downhill from the very beginning. I use Costco's Kirkland brand because they are generally cheaper for the heavy duty than others standard model and most importantly, they don't give you any hassle when one goes bad. They don't even test 'em, simply give you another under warranty. They are no better than anyone elses because they are made by JC also. Don't let anyone tell you that XYZ brand is a terrific battery today and all the rest are junk because THEY'RE all junk now! I've noticed that even Wal Mart has a 3 yr free replacement now, with NO mention of any additional warranty where their best battery used to be 3 yr free and prorated to 84 mo. (7 yrs.) My son's 770 CCA Wal Mart battery in his '08 Suburban lasted less than 9 mo. before it failed completely. Said made by Johnson Controls right on it!
BTW, the reason Motorcraft is now JUNK is because it's made by JC!

 

Absolutely NOT!!

Don't ever disconnect the battery with the engine running! The Di/Dt from disconnecting the battery cable will create a voltage spike, and there will also be voltage spikes from the alternator. These voltage spikes will destroy electronic components like PCM, GEM, etc.. The battery acts like a filter (capacitor) to eliminate the voltage spikes from the alternator.

If the voltage is around 14V when the engine is running the alternator is OK.