Voltage and charging problem

[Pirtekpyro85]

2004 Dodge Ram 2500 Having a charging issue. Couple times in the last year the passenger side battery has boiled and replaced the boiled battery and heat sensor under drivers battery. Worked fine for about a year. When new mat battery started venting one night. Took battery out and ran with one for awhile. But decided to swap batteries after mat battery tested good . Last night my battery gauge pegged to the 8 . Truck stayed running. Lights never flickered . Radio stayed on ect. When I got home I shut it off. Check belt. Battery . Connections. Fired truck back up and it then showed 12v. Shut off again and it progressively got harder to start( figured it was just starting off battery and alternator wasn’t charging) tested alternator today. Tested low at 13.5. Average 14.5 and high 15.2. ( good) brought back home put back in truck fired up. Ran where it had been since I got it. Note previous owner had passenger battery boil once before as well. I used multimeter. Passenger battery running 16.5. Drivers 14.7 and alternator putting out 16.5v . I’m leaning towards installing external voltage regulator but figured I’d see what you guys have come across to fix it

 

[AH64ID]

Your crossover cable is likely bad, and been bad for a while.

The ECM monitors the voltage on the driver side, but the alternator charges from the passenger side. With a bad crossover cable the ECM seems lower voltage than the alternator is putting out and bumps the voltage up.

Don't install an external regulator. It won't fix the issue, or the different voltage readings.

 

[seafish]

More then likely the either the connections or the actual wire of the large crossove cable that connects the two batteries is failing. You need to carefully remove, clean and inspect the terminals of first the ground cables and then the actual crossover cable.

NOTE: in a dual battery system BOTH ground wires must be removed before attempting to disconnect the XO cable form the batteries.

The XO cable often fails UNDERNEATH the insulation....the wires themselves become corroded !!!! In order to make sure you can slice the wire insulation back from the terminal (parallel with the wires) about 4 "" and then look for green or white corrosion in the wire itself. If no corrosion is present on either end, the cable can be taped up again, but if there is, it should simply be replaced.

 

[Pirtekpyro85]

Thanks guys I’ll check that out when I get home after work

 

[Pirtekpyro85]

Thanks . I’ll check it out when I get home from work

 

[KParsons]

had the same problem this summer. bad cable!

 

[Pirtekpyro85]

Thanks . Removed cable and checked both ends. One side had lots of green and terminal bolt was badly rusted. It took me a bit to find an auto parts store that had the cable. Put new one in. Sprayed some anti corrosion on all bare metal battery areas. Truck fired right up . While running both batteries now ready 14.6v . Working great. Saved me slot of time and money

 

[Motorhead]

I ruined a 3 year old, Sears Diehard Platinum (Odyssey gel) just because of the same thing. I didn't have any rust or corrosion. Darn cross over cable on the drivers side was loose. Couldn't warranty it because local Sears had closed.

 

[slowmover]

Best to replace the entire set. See www.custombatterycables.com

Those of you not treating a system as a whole will have the highest costs, the worst reliability and the shortest vehicle life.

1). The entire set is now too old. Pony up and do it right. Everything.

2). Vehicle bonds (grounds).

All need to be replaced and/or upgraded
same as with battery set:

1). Crossover/starter/alternator. Nothing old loose cracked frayed or unsecured. Oily? It’s gone.

2). See wwwk0bg.com for how to DC electrical ground.

EVERYTHING will work better for what’s mainly labor to upgrade grounds.
1” braided copper strap plus a Dremel; Dow#4 plus paint.

3). Any crummy extra wiring needs to be ditched and to start over with a properly fused distribution box plus relays. Marine-Grade wiring and connectors/terminations. Blue Sea or Painless

4). Batteries need to come out and battery boxes re-habbed.

The failure to keep the electrical primary Brand New will ruin a vehicle too fast. The increased resistance makes everything work under a strain.

Broke? Then this where you start.

All new exterior lamps if more than 3-years old.

1). Clean contacts.
2). Measure voltage at idle & with alternator kicked in.
3). Dow #4 on both ends.

Cars & pickups don’t get old. Wiring does.

.

 

[Motorhead]

GREAT write up ^^^^^^^!
I have been doing Automotive electrical for over 50 years and ONE ground that is bad or a weak connection can cause a NO start, poor running and It happened to ME was that the cross over cable got loose and cooked a $250 Oddysey battery on the passenger side.
I'm sure there was a method to Dodge's Madness with our charging system craziness in how it is hooked up. What ever happened to just putting a Voltage regulator on the system instead of what we have now.

Years ago, I had a 1972 Volvo Wagon with the first year of Bosch fuel injection. The car ran well and we drove it 400 miles up to Lake Tahoe so I could go Snow Skiing. Had a good week, had the car packed up from the Hotel and even had Bud and Cory, our two Doberman Pincers loaded up. Went to start the Volvo and Crank-Crank-Crank, NO start. My WIFE said, I don't hear the fuel pump running. I raised the hood and started looking at things. Just so happened that the fuel pump relay was under the hood and it had a GROUND pigtail that came from the relay and went under the relay mounting screw. The screw had come loose and the ground had faulted! ONE, Three inch GROUND wire disabled a whole car from starting and running. My lesson was learned!

 

[Pirtekpyro85]

Changed crossover cable and checked all connections I can find. Everything was tight and truck voltage worked great for couple days. Then the other day gauge light cane on and voltage dropped to 8v again. Went to Napa and had them check batteries and alternator on truck under load. Drivers battery voltage was a little low ( figured that’s where truck draws power from first. So assumed it would be a little low) the alternator tested bad it was only charging to 11.8v . Not one to take first opinion I then went to O’Reilly . Batteries tested same . His machine wasn’t nearly as nice or thorough but he said the voltage output was jumping around between 12 and 14 v but ended up passing( at this point the gauge was back to normal and seemed to be charging again) . After that ran fine for rest of the weekend but drive a bit yesterday and voltage dropped again. Would you guys go for the alternator next ( it did bench test good)

 

[DavidC]

Does the 04 still have the sensor under Driver's battery ?. If so more checking is involved, find the test procedure. How many miles on truck ?

 

[Pirtekpyro85]

Does the 04 still have the sensor under Driver's battery ?. If so more checking is involved, find the test procedure. How many miles on truck ?

Yes it has the sensor . Replaced that last year when the passenger battery over charge and boiled. Roughly 230,000. What test procedure ?

 

[Motorhead]

I believe my 2001.5 had it too

 

[DavidC]

This is for a 99, probably the same
BATTERY TEMPERATURE SENSOR
To perform a complete test of this sensor and its
circuitry, refer to the appropriate Powertrain Diagnostic
Procedures manual. To test the sensor only,
refer to the following:
(1) The sensor is located under the battery and is
attached (snapped into) the battery tray (Fig. 1). On
models equipped with a diesel engine (dual batteries),
only one sensor is used. Location is under battery
on drivers side of vehicle. A two-wire pigtail
harness is attached directly to the sensor. The opposite
end of this harness connects the sensor to the
engine wiring harness.
(2) Disconnect the two-wire pigtail harness from
the engine harness.
(3) Attach ohmmeter leads to the wire terminals of
the pigtail harness.
(4) At room temperature of 25° C (75–80° F), an
ohmmeter reading of 9,000 (9K) to 11,000 (11K) ohms
should be observed.
(5) If reading is above or below the specification,
replace the sensor.
(6) Refer to the Removal and Installation section
for procedures.

 

[DavidC]

If you get a store bought alternator buy it outright and get a rebuild kit for your original. I have not heard positive reviews for the parts store alternators. It could be as simple as changing the brushes. 230k could be rebuild time.

 

[slowmover]

Cables that are tight doesn’t reveal corrosion that may have crept a foot back from termination. Or show cooked cover in an out of the way place.

Remove them all. See diagram in my first link.

Same for grounds. Appearance isn’t enough.

Disassemble.

.

 

[slowmover]

GREAT write up ^^^^^^^!
I have been doing Automotive electrical for over 50 years and ONE ground that is bad or a weak connection can cause a NO start, poor running and It happened to ME was that the cross over cable got loose and cooked a $250 Oddysey battery on the passenger side.
I'm sure there was a method to Dodge's Madness with our charging system craziness in how it is hooked up. What ever happened to just putting a Voltage regulator on the system instead of what we have now.

Years ago, I had a 1972 Volvo Wagon with the first year of Bosch fuel injection. The car ran well and we drove it 400 miles up to Lake Tahoe so I could go Snow Skiing. Had a good week, had the car packed up from the Hotel and even had Bud and Cory, our two Doberman Pincers loaded up. Went to start the Volvo and Crank-Crank-Crank, NO start. My WIFE said, I don't hear the fuel pump running. I raised the hood and started looking at things. Just so happened that the fuel pump relay was under the hood and it had a GROUND pigtail that came from the relay and went under the relay mounting screw. The screw had come loose and the ground had faulted! ONE, Three inch GROUND wire disabled a whole car from starting and running. My lesson was learned!

Newlywed ?

Thank the good Lord His Son tapped you on shoulder, said, “Look there”.

You remembered that story for more than one reason.

And, thank you.

 

[3rdGenGuy]

The ECM charging circuit on 3rd Gen’s was a bad idea. A bad ground in that circuit will cook the primary field control circuit and also boil your passengers side battery. In lieu of a new ECM, I installed an external voltage regulator and used an LED ballast to at least make the ECM think it’s doing something; I don’t have a dead Needle in my dash that way but it’s just a dummy circuit. My charging system is running at about 15 volts, without the temp sensor in the driver’s side Battery Bucket. Not a perfect solution though. My truck needs a new ICM and ECM. It’s in the works

 

[AH64ID]

The ECM charging circuit on 3rd Gen’s was a bad idea. A bad ground in that circuit will cook the primary field control circuit and also boil your passengers side battery. In lieu of a new ECM, I installed an external voltage regulator and used an LED ballast to at least make the ECM think it’s doing something; I don’t have a dead Needle in my dash that way but it’s just a dummy circuit. My charging system is running at about 15 volts, without the temp sensor in the driver’s side Battery Bucket. Not a perfect solution though. My truck needs a new ICM and ECM. It’s in the works

If only one battery is boiling the problem isn’t the ECM, it’s most likely the crossover cable.

The only way to get one battery to charge more in a 2 battery system like these trucks is to have a bad connection between the 2, or a bad battery.