2000 Dodge Durango SLT 4.7L (general mechanical question, not model specific)

Okay, so after a long weekend of sitting the truck wouldn't start. So i hooked up jumper cables and went to jump it, at first it wouldnt start right up, very sluggish and took bringing the RPMS to approx 3k on the HELP vehicle to get mine to start. Once it started it did that thing where it can't hold idle without stalling so I kept the RPMs at 1500 for about 5 mins. During this time I noticed my charge gauge on my dash go to 18v (I figured bad voltage regulator in my altenator). After a short 18v overcharge reading it dropped back to its normal ~14v. So I took it for a little drive to charge up the battery. I shut it off and turned it back on right awayto notice that the battery was again DEAD, interior lights glowed that dim amber and the instrument cluster was unstable/blinking. So I figured okay, no big deal, time for a new battery. Just to test this I disconnected the leads to my "dead" battery and connected the jumper cables directly to the + and - leads of the system, the engine would barely even crank. Now is this because of a bad starter, or because the HELP car cannot produce enough current to power my starter motor?

I was fully prepared to order a new altenator and battery and install this weekend, but now I'm starting to think I need to investigate the starter as well. Its fairly evident that the battery is shot, it cant hold its charge for any time and isnt really accepting a charge. I assume the voltage regulator in the altenator is bad because of the overcharging I saw. (the two could have caused each other). But the altenators charging function seems to be working in that the car ran just fine after being jumped during my short drive. Do altenators give a false overcharge when they are coupled with a battery thats shot?

Anyone spot anything that I am over looking? I tried doing a slow 24 hour charge of the battery on a garage charger and as soon as I hooked it up and tried to crank the engine it was done.

Any ideas as to how to test what is causing this? I have a feeling its 2 of the 3. Either bad alt/batt, bad starter/batt. I am hesitant to replace the battery and see because I dont want to fry a new battery because I am over looking somthing.
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put a DVM on the battery while the truck is running, should be between 13.5 and 14v, if so alt is likely fine

replace the battery and see if it will start, it really sounds to me like your battery is completely toasted, you may have a short in the systme somewhere which drained the battery all the way (which will definitely kill the battery, as in wont recharge).

my feeling is you have a bad battery and maybe corroded battery cables (internally corroded), you will have to take a look for yourself

 

Yeah, thinking the same exact thing i completely removed the positive terminal strap and used a service bug to connect braided copper wire to the factory bug that connects the fuse block lead to the ?starter? lead to the battery post. There could still be corrosion inside the factory bug which my adhoc battery post connector wouldnt have solved but it seems so sudden.

I guess my question is: when i connect jumper cables to a dead car with NO battery is it expected to be able to jump it without an issue? Does the booster cars battery/alt produce enough current to power the dead car with no battery at all?

 

I had the same issue with mine it, took me about 6 months and every electrical component replaced to figure out what the problem was... Check your wiring harness, just before it goes thru the firewall, for a wire that may have been rubbed through. ( For me it was a black wire with a pink color stripe that is in the fuse box inside the engine compartment and connects to the electric seat and then to the rear window defrost.) My harness does a looping 180 type thing before it goes thru the firewall, it rubbing while driving, rubbed thru the mesh around it and then thru the sheathing on the wire itself, the battery would go dead within 5 minutes

Best way to figure it out (for me) was to get a volt meter, another person and remove all of the fuses, and watch the battery drain while putting the fuses back in. Once it starts rapidly draining (and it was very rapid), that is where the problem is, then the fun part is tracing it out to source.

I cut the wire at the box, butt spliced a new wire, ran the new wire thru the firewall on top of the wiring harness, and then butt spliced back into the original wire. (For easier access, take out the drivers seat) I also put a piece of Dynomat on the metal under the harness to alliviate the rubbing issue.

Hope this helps and good luck!!!

 

Okay, so i replaced the battery. Turns out the truck runs just fine. No overcharging, as previously seen. I think cells shorted on the battery (just from being very old) and this shorting of cells was causing the charge gauge on the dashboard to read a false intermittent overcharge. Starter is just fine, no hiccups.

Crazy how an electrical issue can spawn so many other phantom problems. Anyway, I will keep everyone updated with how/if this progresses any further.

 

pretty much what i was thinking