Battery issue

[behindbars1544]

Today I went to start my 05 Yukon and...nothing. I mean the door locks weren't even working. I called AAA for a jump and had them test the battery.
Wit a jump she started and seemed to keep good voltage but as soon as we turned the ignition off the battery voltage plummeted to almost 4volts and wouldn't start without a jump. I just purchased this truck about a week ago so I had the guy jump start me again and drove it right to the dealership. I felt like a total ass because after telling him all the BS me and the AAA tech went through and I had to keep it running because if I shut it down it would need a jump to start again, we went for a ride and when we got back to the dealership he shut it off by mistake. Just for the hell of it he tried starting it back up and ....bam...she started right up no problem. I was like, WTF!! He replaced the battery with a new one anyway but the one that was in there was only 4 months old.

Can anybody suggest WTH happened and how I can fix it?
BTW, the only thing that was left on all night was my cell phone charger which I leave on every night even with my old vehicle and never had a problem.

Thanks guys!!

 

[tt54l32v]

Battery had a short in it, ran into it the other day. That battery had about 100 more cold cranking amps than it was rated for. So I cleaned all the connections and tried a couple of times in a row and sure enough it got weaker and weaker and after 3-4 tries it wouldnt crank the engine. Let it run for about 30 minutes and it would crank a couple of times and then just short out and act like it had no connection, but with a volt meter it showed low voltage ensuring a connection was present.


In short, new dont mean shit.
Batteries made in the last 5 years are all pretty much junk and can only be trusted as far as you can throw them.

 

[OHSIXX]

Internal issue with battery like stated.....possible short or dead cell(s).

 

[behindbars1544]

God I hope so. Thanks guys!!

 

[behindbars1544]

Ok, update. Went to start the truck Saturday morning and it cranked over slow as if it didn't have much life left. Mind you this is with the brand new battery that was installed less than a week ago.

I think something is draining the battery but everything obvious turns off when I shut her down. Any suggestions on how to go about diagnosing this problem??

 

[Chiggy]

quite possibly a bad ground somewhere and it's not charging correctly. I would suggest doing the big 3 and go from there.

 

[oh1yukonslt]

quite possibly a bad ground somewhere and it's not charging correctly. I would suggest doing the big 3 and go from there.

X2. Also check your alternator. Been told a bad diode can drain a battery overnight. Also you can do a parasitic draw test using a volt meter to see if any electronics are pulling juice while off. Did you install any electronics ie: stereo etc etc?

 

[harveje]

What is the procedure for doing the parasitic test? I know on our 08 that stuff stays active for x amount of time after last door is closed. Also is there a way to trick the alternator or computer to charge more? The ECM or PCM has some kind of program that controls the charging circuit based on different variables.

 

[08grey]

I think you have a bad ground or connection. Before the new battery you mentioned the old one shorted out. And now with the new one it sounds like sits not getting a good charge which first step is to look for a bad or loose connection and it corrosion on the copper wire.

---------- Post added at 10:26 AM ---------- Previous post was at 10:25 AM ----------

You tube big three

 

[behindbars1544]

....and we're dead again this morning...
I thought these trucks supposed to have something that prevents the battery from draining to low. It's on my window sticker.

---------- Post added at 12:50 PM ---------- Previous post was at 11:59 AM ----------

Thinking it's my diablo trinity tuner draining the battery overnight. When I researched it there seems to be a lot of issues with the trinity doing this. Truck didn't give me any starting issues before installing the trinity but I only had it like 4 days before I installed it so I cant say for sure.

I called Diablo today and spoke to a tech rep and he told me to change to sleep mode from 30 seconds to 60. Mine was somehow set to 5 seconds. The way he explained it was the trinity contacts the vehicles computer every, in my case, 5 seconds for information and was "keeping it awake". Said if the trucks computer took say 40 seconds to power down and the tuner was contacting it every 5 it was keeping the computer awake and not letting it fully power down which in turn was keeping a drain in the battery.

Still don't understand why the part that supposed to prevent battery from draining to low didn't stop the drain.