Jeffrey O'Hara

Hey I need some input from knowledgeable members. My 2008 Ford F150 has a Duralast Gold 65S-DLG battery. The CCA is 750, 935 @32F and a reserve capacity of 140. The battery is a little over a year old but I'm having charging system problems. The battery light will come on and the "check charging system" message appears on the cluster.
I've been trying to fix the problem but I'm not sure where to go from here. I didn't record the values (I should have) but it seems like the battery is draining when the battery is disconnected from the truck. I disconnected both the negative and positive leads on the battery and let the truck sit overnight. I'm pretty sure that last night the voltage reading on the battery was 12.74V and this morning it was 12.66V. I don't know much about batteries but could it be possible that one of the cells is bad?
I also noticed something else. I hooked the battery back up to the truck and watched the voltage reading for about 20-30 minutes. It dropped from 12.66V to 12.65V. I also did a parasitic draw test and it wasn't drawing any voltage. This is why I disconnected the battery to see what was happening with just the battery. Another issue though is when I hooked the battery back up and started the truck. It fired right up and the voltage readings showed 14.3-14.4V indicating the alternator is working BUT when I turned the truck off the voltage of the battery was reading 12.55V!? It was only running for 2-3 minutes. I'm confused. Can someone please offer a possible solution?
I went to O'Reilly's and both the battery and alternator checked out. He basically checked the 12.74V battery that I just charged and I'm assuming checked the CCA and he also saw the 14.3V reading when the truck was running that is why he said alternator was good. I said "what?? that's confusing" because I couldn't find the problem and apparently I can take the alternator off the truck for a more in depth test but it seems like more work than I'm interested in doing right now.

My main questions are... can my battery have a bad cell and that is why it is self-discharging slowly? Would the employee pick that up on his test? Can my alternator read 14.3V but not be charging the battery? Is it possible to have a bad diode but the reading is still 14.3V?

redfishtd

Current draw is what you need to look at . Current from alternator builds up the battery . It has to run at a higher voltage to push current into battery .
Norm push is between 14.2 to 14.4 volts .
Capacity of a battery is another thing, physical size, number of plates etc . Electrolyte condition can be checked with a hydrometer . That shows the health of each cell .
I see nothing wrong with your readings .
All batteries go down slowly when sitting, your drop is not significant .
I believe you have a indication problem ,probably from alternator circuit . These trucks are sensitive to non oem alternators .I don't know the exact cause .Some alternators let an ac volt component thru and that's not good . It can be viewed with a scope or a real good digital meter .
Parasitic draw should be down around .02 amps you can monitor that overnight . Voltage is the pressure or push , current is the draw-- it measures the electrons leaving .
A water dam has pressure depending how full it is , any leak will be flow like the current draw, its takes flow to discharge the dam . The size and capacity of your battery corresponds to the size of the water dammed up that's like its cranking amps or reserve power.
Just like the dam some water is going to be lost evap etc . Your battery is going to lose electrons and degrade chemically if not on charge . Heat destroys batteries .
Usually the regulator on the alternator converts ac to dc and filters it , the indicator circuit triggers if the output volts are to low . Which is not your case that's why I say you have a poor check circuit for your trucks taste . They seem to act up with some aftermarket alt .
Some one on here may have a better handle on this exact cause , it is common problem on these trucks . I haven't fought it yet .

redfishtd

Try cleaning plug on alternator pins and connector.

Jeffrey O'Hara

Alright so I just spent that last 30 minutes watching the readings on the battery haha. I put the battery on the charger earlier today and after multiple hours the charger indicated it was still charging (turns off automatically). I have had the charger indicate it was at full charge before but not this time. I was impatient and figured I didn't need to wait until the charger turned off. Anyway, I took the charger off and hooked up the multi-meter. I took a picture with my phone and it was 6:08p.m. and the battery had a charge of 13.07V. I waited 30 minutes and it was now 6:38p.m. and the battery charge dropped to 13.02V. Apparently what I said before was incorrect because the battery is draining a lot quicker. So I lost .05V in 30 minutes. I am assuming if this is constant that I'm losing 0.1V every hour! This is with the battery disconnected from the vehicle. Why is this happening? I'm planning on going to Autozone because I bought the battery a little over a year ago and it is still under warranty.

Jeffrey O'Hara

So could I have 1 bad cell that is draining the rest of the battery?

Jeffrey O'Hara

I'm confused. I just checked the battery at 7:08p.m. which is 1 hour after the first check and it was 13.01-13.02V. Not sure why it's not draining anymore? Confusing.

nrivera04

Bad cells would net you 2V loss per cell. .05 volt change could just be from coming off the charger. Bring the whole truck to autozone and have them check both starter alternator.

bigbadjackeduptruck

A voltage regulator that is not performing to spec could be what redfishtd is describing. When it comes to battery I am mainly concerned with the cold cranking amps (CCA). Since that determines if I can start my truck or not. To troubleshoot your problem, I would try swapping out the battery to see if the check battery light goes away. If you ever need a good and cheap battery CCA tester, get the

Schumacher BT-100

It's only $20.

techrep

iTrader: (1)

What happened to the center plug on your ECM ?

Jeffrey O'Hara

nrivera04, that is one of my problems. I already took the whole truck to O'Reilly's and had them check the charging system. I'm not sure what he checked but I'm assuming he said the battery was good because it was reading around 12.74V and I'm guessing he tested cold cranking amps. Once I started the truck the reading was around 14.4V so he said everything checked out. That's when I was like "what!?" and basically I would have to take the alternator off the truck to have them bench test it. Other than that I'm not sure what else to do.
Techrep, I'm not sure about that lol. I just got the truck back from the dealership and I had my ECM replaced. When I got it back I was like what the hell is up with that center plug? I don't have a picture or proof of what it looked like before I took it in so I'm not going to try and argue with them. I noticed it looked different but hopefully it's not an issue.