Electric Problem

[Txindprop]

I have a 2015 2500 Cummins. Fairly stock, have an Edge tuner and K&N air filter setup. Have a ***** front and back, front ***** is wired directly to main battery (drivers side). I also have a back ***** but have a solenoid on the firewall that is connected to dash button which cuts power too *****. Recently installed a light bar in grill and fog lights in front bumper, wired directly to main battery through a dash switch and each circuit has individual fuse. I tried to make a clean install since I like to get out in the boonies.
Did not run the truck for about a week. Went to start yesterday and deader than a door nail, nothing. Both batteries had about 1 volt. I put on 10A trickle charger and took old faithful Toyota out for the day. Last night had about 12.5 volts in each battery, the starter clicked once and would not turn over. Everything else on truck is dead.
Both batteries are big Mopars and less than 6 months old. What could drain both of those batteries overnight and not blow a fuse? That is my next step to pull fuses and check them all. Crawl underneath and check wiring, is there a main circuit breaker of fuse?



Checked every wire and connection I could find, everything looked good. Had on trickle charger for 4 or 5 hrs, disconnected both batteries (to reset computer) Reconnected both batteries, checked voltage on both batteries, secondary battery was about 6 volts, primary battery about 4 volts. Everything is dead dead, no buzzer, no dinger, no accessory lights, no overhead lights. Going to run into town and get a new multimeter and start pulling fuses. The really weird thing is the accessory add on LED lights, wired directly to primary battery, fused circuits with dash button, one bar in grill and 2 fogs in bumper and both dead.

 

[Hootbro]

You got a lot of stuff going on there. I would disconnect everything accessory wise off those batteries first, attempt to charge and go from there.

Once it is determined there is no battery issue, I would back one system at a time and check with a amp clamp meter for parasitic draw and narrow down the circuit in question.

 

[Txindprop]

Thanks for reply, I am going to disconnect both the battery's and see if the computer will reset then as you suggest hook everything up one at a time and check for a draw..... as soon as it quit raining. I was hoping someone knows a "magic button" I just cant figure out what can draw down those big new batteries overnight and not blow a fuse or start a fire.

 

[Hootbro]

I do not know what your skill level is on electrical troubleshooting. I work on aircraft electrical system every day and my troubleshooting thought process is to divide the problem in half and figure which side to go forward from. In your case, you need to figure out if you got a battery/charging problem and/or a draw problem.

Removing the accessory stuff and getting back to "as built" configuration will let you know if the batteries took a dump or if the problem is on the accessory side that was induced by you. Just keep in mind that if you have a battery/charging issue, once it is fixed, still need to check your accessory side of the equation to make sure you did not induce your problems again and you are back at square one.

Attached is basic video on parasitic draw testing. Without a good meter that can measure DC amps, you can be chasing your tail on this.

 

[Txindprop]

Thanks for the reply, I am following the same train of though I can't figure out how the batteries can be drained so quickly, it is a diesel and has 2 big new batteries (6 mo old Mopars). I left the trickle charger on all day yesterday and had about 13 volts, this morning they were almost dead again so I don't think it is the charging system..... I have a multi meter that reads DCmA in the ranges of .5A, 50A, and 250A, which range should be the proper one to use. Also use an Ohm reading on the accessories before I reattach (non of which have been turned on) and are switched and fused off the battery, to look for a drain?

 

[Hootbro]

DC mA (milliamp) range is too low of a amp scale for troubleshoot vehicle electrical. Need similar meter like shown in the video that has at least a full 10 amp scale. Your milliamp range only meter will likely get blown on the high amp circuits you have.

Also, the dual battery setups are in parallel to each other. That means both batteries tend to level each others state of charge between them. When one goes down, it drags the other down and is why they recommend replacing both batteries at the same time on this setup regardless.

Also, voltage does not tell the whole story alone on battery state of charge. It is voltage drop under load that will tell the tale. One test to do on checking batteries is that after a fresh charge, put a load on it like turning on just the headlights for like 30 seconds and then turn off. Then measure the battery voltage and if it drops below like 12.3 volts and does not climb back up on its own to at least 12.5 after a few minutes, then the battery failing under load and that is usually a plate issue inside the batteries and many times that is due to sulfating between the plates. When you have a place like Autozone test your battery, this is basically doing the same thing their tester is doing that is putting a load on it and checking state of charge and state of charge retention.

Troubleshooting electrical stuff over the internet sometimes is like doing heart surgery over the phone. If you were more local, we could probably have this licked in about an hour.

 

[Txindprop]

I appreciate your time Thanks! Agree this is about the hardest way to diagnose but I live 20 miles from nearest town and nearest dealer is in Hot Springs which is about 40 miles. Question on battery, I have a light bar in the grill and 2 Four beam fog lights in the bumper that are on their own circuit, switch and fuse. After the battery has been on trickle charge for several hours they still will not even glow. My first experienced with the multi beam light bars. Thanks again

 

[Txindprop]

Ok..... quit raining so I can get on truck. Do you know what is attached to the Neg terminal on the drivers side battery, it is a small black plastic box and has 2 wires running out of it into a wiring bundle. It appears to sit on a piece of plastic insulation type material on top of the Neg terminal

 

[Hootbro]

Ok..... quit raining so I can get on truck. Do you know what is attached to the Neg terminal on the drivers side battery, it is a small black plastic box and has 2 wires running out of it into a wiring bundle. It appears to sit on a piece of plastic insulation type material on top of the Neg terminal

It is a "Intelligent" battery sensor. One wire goes to the body control module and another to a power distribution block. It feeds the body control module information on state of charge and in turn control the alternator charge voltage output. In the older systems without the sensor, the alternator just put out basically a constant 14.5 volt DC charge voltage most times regardless of battery state of charge. With this intelligent sensor, alternator charge voltage slides up and down based on battery need.

If you hooking some of your accessory wiring to this sensor for your grounds, that may cause a problem in how the alternator charges your battery but I would not go so far to say that is your problem or only problem here.

 

[Txindprop]

Thank you Sir, appreciate it, makes sense. Pulling battery this morning and running into town to get it tested and get a 20A Multimeter.
Nothing attached directly to sensor on Neg post, however they all attach to the "plate" attached to sensor on Neg poost