What could cause this? (pics)
 

Just found this today after my check gages (low voltage) light came on. Two brand new (bought 2 months ago) Sears P2 $200 batteries. I posted in the HELP section earlier but need to get my rig back on the road for a long trip asap. Is it just a bad battery? What could make this happen?

There was a thread on here some place about a wire between one of the batteries to the ECM, and if it gets corroded the ECM sees no voltage from the batteries, so the ECM turns the alternator to full output.

Other than that, high resistance at the battery post/clamp? Tarnished or oxidized?

Bad/loose cables build lots of heat, enough to melt plastic.

Here's an excerpt posted by J BODY in a previous thread, that might be helpful.




We'll start at the alt. There you will find a large wire that goes directly to the right batt. You'll then follow the cross cable over to the left (drivers) batt where it connects to the B+. From the B+ the cables go to the ECM eventually. Here's what happens, or what I've experienced more than a few times. Corrosion or poor connection. I've seen it at either battery, but more so at the left battery where the cross cable is bolted up. The ECM monitors battery voltage and if it falls below a certain threshold will full field the alternator to increase the charge. That creates a prob if the voltage drop is excessive from the alt all the way over to the ECM where B+ is monitored. The ecm will see a low voltage and bring the charging level up..... unfortunately this can hit the right battery with up to 16 volts. If anybody wants to play around with this grab your DVOM, unhook the cross cable at the left battery and start your truck up (safety glasses/face sheild highly recommended). You'll find excessive charging voltage at the right battery, but only stable battery voltage at the left. The ECM will only see the voltage of the left battery and ramp up the charging. If for some reason you're boiling batterys and the voltage is high at both batterys, you'll need to find where the high resistance is on the 12v feeds to the ecm.

You just escaped a bullet.
That battery terminal was on fire!
If it had been wildly overcharging you would see signs of battery acid bubbled out over the battery, plus you would have gotten a dash light indicating the fault.

About the only that would cause that would be arcing caused by a loose connection.

Is it possible the Sears "mechanic" failed to clean the cable end clamp or to tighten it properly.

Beyond that these era Dodges were quietly notorious for spontaneous battery fires.
I bought an 2001 that had a battery fire, fortunately the former owner saw smoke from the parked truck and extinguished the fire before engulfed the entire vehicle.
His small town dealer stated nearly every dealer knew of trucks that caught fire in the same manner, but evidently Dodge company kept it quiet and it the issue never received the attention that would have resulted in a recall.

Though my truck has all new underhood wiring I still think about the possibility of a fire to the extent I never park it inside.

If you ever look at the actual wire sizes and the overloads they handle it's a wonder more vehicles don't go up in smoke. The wiring is truly rinky-dink.

Dodge isn't the only one chinsey on wiring, BMW vehicles have had some major wiring problems.
It's what one should expect since a great engineer today is one that can get a vehicle to bust within months of the end of the warranty.

Not sure about the loose connection. I installed them myself, and scrubbed and cleaned the terminals, put the felt corrosion protectors on, and tightened em all down extra firm. There was no play that I know of, but then again I didn't recheck. Never thought about it being an issue on any battery I've changed. Seems bare wire arced somewhere, but today I went all over the engine bay and didn't see any wire worn or exposed.

I took them in to Sears and both batteries were dead. They're being recharged to see if they'll hold; so I'll know more tomorrow. Could it of somehow been the alternator going bad? Just want to rule it out.

But, as per Jeff in TDs post, a low voltage reading to the ECM because of a corrosion (which I didn't see any) or a loose wire could have caused the overcharge. Still investigating.

subscribing because I was just about ready to buy two of those exact batteries...

If both batteries were flat dead, I wonder if one could have an internal defect/short? That could put a huge current load on the cable and clamp.

Kinda what I was thinking when the guy put the tester on and found em both drained (almost). Funny thing is the fried one still had a little juice left in it; and the other was a 60lb paper weight.

AC/DC says it best... "Loose wires cause fires".

Could be the paper weight one has the dead short, and the other one had a little juice due to resistance in the cable that hooks them in parallel.

Time on the charger will tell. Once the batteries are replaced (personally I'd replace both) I'd be sure to look at charging voltage at the battery posts of both batteries with a pocket meter.

I put those exact same batts on my truck about 4 mos ago and so far....knock on wood...no problems. Both of my negative cable ends are just about shot....the acid from the leaking factory batteries pretty much dissolved the bottoms of them. So, I was a tad leery about them coming apart and arcing causing a fire. Really need to find a set of cables from a wrecking yard or something to prevent that from happening. But, like I said, so far so good. No negative info from me on those batteries.

Went to the mechanic today to test the electrical system (my first chance) and they put a tester on the driver side battery (I've got the other one still out for now, don't want to re-fry it til I get this figured out), it read 12.5 volts (running). They told me even with one battery in it should still read 14.+ volts in the system. Is this correct? They thought it could be the alternator, but I told them about the voltage regulator problem. They said I need to go to someone with a high end SCAN tool and it would read all the parameters I'd need to know where the issue is. True?

If the voltage regulator has a short it can send a signal to the alternator to overcharge the batteries. Where is the voltage regulator exactly? In the ecm or On the ecm? Is it something that can be replaced without replacing the entire ecm?

Any other potential places I should be looking at?

You should see much higher voltage than 12.5 with the engine running.

I believe the regulator is built in to the ecm.

What was the voltage with the truck off? I'm wondering if the alternator isn't working. Maybe it could be bench tested?

I really dont want to hijack this thread but i want to join into this conversation as well since i have a similar problem.

My issue is this.
Wehn to start the truck, and it lost all power for a split second. Right away it came back and started fine. I monitered the voltage gauge as i drove and found it to be on the low end of the "Normal".
I figured the altenator was finally bad. I got to work and figured id check voltage on the batteries with the truck running. Found the drivers side to only be a 12.2 volts. Went to the passenger side only to find the fluid cap had blown off and spewed acid throughout. I checked its voltage just in case to fine 13.4 volts on the boiling battery.

Seems to have a short somewhere. I pressed the cap back in and attempted to drive home. Made it about 100 Yards before the truck lost ALL power again. This time it was for about 5 minutes. Seemed like a circiut breaker and i thought if i found a bad one or a blown fuse, itmight help track down the problem.

As i was on the side of the road under the hook, i left the key on so i could hear if/when power came back. I was digging around in the fuse pannel, specificly, i was reading the designations of each fuse on the lid when power came back. I hear a click in front of the fuse box under the hood, behind the headlight area.
I unhooked the boiled battery. Truck starts, runs fine and voltage is where its expected.

When i lost power to the truck, there was a light flashing next to the Temp gauge. It was flashing at a constant rate and gradually slowed to nothing.

I will be tracing the B wire to the ECM to see if i have corrosion somewhere. Thats really the only place i even know where to look. Im totally lost here.

Bad thing is Dodge is completly out of stock of all battery cables for this truck for a couple more months.

Ill be following this thread closely.

BTY, my batteries are dang near new too. Only about 3 months old. With completly clean terminals and solid connections.