Serious battery drain

[E.Murray]

I have a battery charger that kicks on automatically when the battery voltage drops. Typically, it will turn on about once a day for a minute to keep it topped off. But on the Viper, it kicks on about every 30-45 seconds. I've pulled all the fuses under the hood one at a time and it kicks on regardless of which circuit is disconnected. Is there another fuse block or fusible-link circuit that could be drawing the juice? I have to keep the charger on the car or the battery will be dead when I try to drive it. Annoying!

[Steve M]

That does sound a bit excessive, but I'm not sure where to start as you've already done what I'd suggest doing. Hopefully someone else with a bit more knowledge will come along with a good idea for you.

[13COBRA]

Aftermarket stereo or anything?

[Steve-Indy]

Well, I would not use the battery tender's ( or charger as stated) to make the assessment of an abnormal drain. I would follow the long standing recommended procedure called Ignition Off Draw (IOD) test...during which one turns off all accessories, allows the timed circuits to shut down, close doors/hood/hatch (being sure that the windows are already down),alarm OFF, and then measure the amps/milliamps of current draw using a digital multimeter between the negative battery terminal and the negative battery cable. If it reads in excess of 25-30 milliamps, you can then start the laborious process of pulling fuses one at a time to detect the area of excess draw. This can take a while...but it is generally worth one's time...and, you have real numbers that are meaningful...and, at the same time you can eliminate the tender/charger as a variable (or culprit).

In my experience, the 6 Battery Tender Plus units currently hooked to 6 Vipers tend to cycle from green to red more frequently than once a day. While I am unable to quote just how many times this happens in a 24 hour period, I can affirm that it seemed to be more frequent with flooded lead acid batteries vs. AGM prior to me switching all Vipers to AGM batteries.

Different tenders/chargers have different algorithms...but, fortunately, the newer, solid state "smart chargers" seem to do a good job for my Interstate or Odyssey batteries.

13COBRA asked a great question...and, I will follow that by asking if any other wiring/rewiring projects have been done to the Viper?

[Patentlaw]

Well, I would not use the battery tender's ( or charger as stated) to make the assessment of an abnormal drain. I would follow the long standing recommended procedure called Ignition Off Draw (IOD) test...during which one turns off all accessories, allows the timed circuits to shut down, close doors/hood/hatch (being sure that the windows are already down),alarm OFF, and then measure the amps/milliamps of current draw using a digital multimeter between the negative battery terminal and the negative battery cable. If it reads in excess of 25-30 milliamps, you can then start the laborious process of pulling fuses one at a time to detect the area of excess draw. This can take a while...but it is generally worth one's time...and, you have real numbers that are meaningful...and, at the same time you can eliminate the tender/charger as a variable (or culprit).

In my experience, the 6 Battery Tender Plus units currently hooked to 6 Vipers tend to cycle from green to red more frequently than once a day. While I am unable to quote just how many times this happens in a 24 hour period, I can affirm that it seemed to be more frequent with flooded lead acid batteries vs. AGM prior to me switching all Vipers to AGM batteries.

Different tenders/chargers have different algorithms...but, fortunately, the newer, solid state "smart chargers" seem to do a good job for my Interstate or Odyssey batteries.

13COBRA asked a great question...and, I will follow that by asking if any other wiring/rewiring projects have been done to the Viper?

Steve-Indy knows what he is talking about as he helped me out with a battery issue. Anybody who can take care of 6 Vipers and not be replacing batteries constantly has it set up properly......

[Steve-Indy]

E. Murray, as I thought about your observations overnight, I realized that I jumped to a discussion of a testing procedure without asking the question: Has your battery failed to perform...i.e. failed to start car or gone totally dead ?

Also, I thought that I should offer an official discussion from Dodge of the test I referenced to be sure that I didn't skip anything of importance. What follows is from the 2009 Service Manual CD.''and, is probably a better written guide for your consideration.

"IGNITION-OFF DRAW TEST

The term Ignition-Off Draw (IOD) identifies a normal condition where power is being drained from the battery with the ignition switch in the Off position. A normal vehicle electrical system will draw from five to thirty-five milliamperes (0.005 to 0.035 ampere) with the ignition switch in the Off position, and all non-ignition controlled circuits in proper working order. Up to thirty-five milliamperes are needed to enable the memory functions for the Powertrain Control Module (PCM), digital clock, electronically tuned radio, and other modules which may vary with the vehicle equipment.

A vehicle that has not been operated for approximately twenty days, may discharge the battery to an inadequate level. When a vehicle will not be used for twenty days or more (stored), remove the IOD fuse from the Power Distribution Center (PDC). This will reduce battery discharging.

Excessive IOD can be caused by:

Electrical items left on.
Faulty or improperly adjusted switches.
Faulty or shorted electronic modules and components.
An internally shorted generator.
Intermittent shorts in the wiring.
If the IOD is over thirty-five milliamperes, the problem must be found and corrected before replacing a battery. In most cases, the battery can be charged and returned to service after the excessive IOD condition has been corrected.

1. Verify that all electrical accessories are off. Turn off all lamps, remove the ignition key, and close all doors. If the vehicle is equipped with an illuminated entry system or an electronically tuned radio, allow the electronic timer function of these systems to automatically shut off (time out). This may take up to three minutes.
2. Determine that the underhood lamp is operating properly, then disconnect the lamp wire harness connector or remove the lamp bulb.
3. Disconnect the battery negative cable.
4. Set an electronic digital multi-meter to its highest amperage scale. Connect the multi-meter between the disconnected battery negative cable terminal clamp and the battery negative terminal post. Make sure that the doors remain closed so that the illuminated entry system is not activated. The multi-meter amperage reading may remain high for up to three minutes, or may not give any reading at all while set in the highest amperage scale, depending upon the electrical equipment in the vehicle. The multi-meter leads must be securely clamped to the battery negative cable terminal clamp and the battery negative terminal post. If continuity between the battery negative terminal post and the negative cable terminal clamp is lost during any part of the IOD test, the electronic timer function will be activated and all of the tests will have to be repeated.
5. After about three minutes, the high-amperage IOD reading on the multi-meter should become very low or nonexistent, depending upon the electrical equipment in the vehicle. If the amperage reading remains high, remove and replace each fuse or circuit breaker in the Power Distribution Center (PDC) and then in the Junction Block (JB), one at a time until the amperage reading becomes very low, or nonexistent. Refer to the appropriate wiring information in this service manual for complete PDC and JB fuse, circuit breaker, and circuit identification. This will isolate each circuit and identify the circuit that is the source of the high-amperage IOD. If the amperage reading remains high after removing and replacing each fuse and circuit breaker, disconnect the wire harness from the generator. If the amperage reading now becomes very low or nonexistent, refer to Charging System for the proper charging system diagnosis and testing procedures. After the high-amperage IOD has been corrected, switch the multi-meter to progressively lower amperage scales and, if necessary, repeat the fuse and circuit breaker remove-and-replace process to identify and correct all sources of excessive IOD. It is now safe to select the lowest milliampere scale of the multi-meter to check the low-amperage IOD.

CAUTION: Do not open any doors, or turn on any electrical accessories with the lowest milliampere scale selected, or the multi-meter may be damaged.


6. Observe the multi-meter reading. The low-amperage IOD should not exceed thirty-five milliamperes (0.035 ampere). If the current draw exceeds thirty-five milliamperes, isolate each circuit using the fuse and circuit breaker remove-and-replace process in Step #5 . The multi-meter reading will drop to within the acceptable limit when the source of the excessive current draw is disconnected. Repair this circuit as required; whether a wiring short, incorrect switch adjustment, or a component failure is at fault."

[Bill Pemberton]

Steve's last post is really helpful and I have one other question I don't think I have noticed , and that is how old is the battery?

[GT Venum]

I had a similar issue last summer. One of the map lights was on and with the angle of the mirror you could not see that it was on thru the windshield when standing outside the car. The side windows are tinted so could not see it shining on the passenger seat. Must have hit it when adjusting the radar detector.

[Steve M]

I had a similar issue last summer. One of the map lights was on and with the angle of the mirror you could not see that it was on thru the windshield when standing outside the car. The side windows are tinted so could not see it shining on the passenger seat. Must have hit it when adjusting the radar detector.

I've made a habit of checking my garage every night before I go to bed just because of stuff like this. Usually the problem is with my wife's car...my girls have a tendency to turn their back seat overhead lights on, and then forget to turn them off. As long as the lights are off in the garage when I check, it is pretty easy to see if something is on that shouldn't be in the vehicles.

This thread topic also reminds me of a key-off battery drain issue I ran into about 15 years ago on my old Camaro. If I let the car sit longer than about 3 days without starting it, I would be greeted with a battery that wasn't totally dead, but also wouldn't turn the engine over. That was my first and only experience going through a key-off battery drain test as outlined by Steve above. The first thing I learned was to use the positive terminal on the multi-meter that is fused for a 10A load. The initial current spike when connecting the multi-meter was enough to fry the more sensitive side of the device, which on mine wasn't fused. Lesson learned there. Once everything settled out, I was seeing a ~70mA draw, so I began pulling fuses one at a time, starting with what I thought were the most likely culprits. I was finally able to isolate the offending circuit, but I could not figure out what would have been causing my issue. As it turned out, that circuit provided power to the OBD-II port. I had a logging device that I was leaving plugged in to the OBD-II port, and that is what was causing my problem. I felt like an idiot, but I never thought something so insignificant could make that big of a difference. I must have killed my battery 5 times before I was finally able to find enough time to diagnose the problem properly.

[E.Murray]

Lots of great suggestions in here. To answer some of the questions: The current battery is an Optima red top (put in by PO... I know...) that's 3 years old. I've already ordered a good deep cycle AGM to replace it. It will go in this afternoon. Yes, the Optima has been fully discharged at least a couple times. I keep it on a charger while I'm working on it. But it discharges so fast that just leaving it off for a day means it's fully depleted. Also, yes, I have an aftermarket stereo setup. But I've pulled the fuses for it, too.
I'm going to do the full test outlined above and see if I can isolate and quantify the draw. Thanks much for all the advice.

[Steve M]

Good call on replacing the battery...once you've fully discharged it that many times, it needs to be replaced.

Please let us know what you find...I've thankfully never had the need to do an IOD test on my Viper, but it is nearly always hooked up to a battery tender. I also have a full aftermarket stereo setup, and many other accessories I've installed that run off of a switched +12V circuit (wideband O2 sensor, shift light, line lock, etc.).

This also reminds me of another random experience I had a couple years ago when replacing my gauge cluster lights - one of the LEDs I had installed many years ago was failing, so I bought new ones. When I was testing the new lights to make sure everything worked before reinstalling the dash, I started having some very bizarre electrical behavior. The vehicle's electrical system would just randomly completely shut off, and then come back on without warning (key on, but engine not running). I thought it was my battery, but a new one didn't fix it. Finally, I put the old LEDs back in, and the problem went away. Needless to say, those replacement LEDs got tossed. I've never seen anything like that before, and I'm not really sure what caused it. My best guess is some sort of short to ground, but it literally shut the entire car down. Freaked me out.

[bluesrt]

my hellcat with 1500 miles on it had the radio/touch screen/ stuck on but did not show on- had to replace it, blank screen when car was off but warm as hell to the feel of the back of it, i pulled it and found that,the screen was cold but the back was warm from not shutting down

[E.Murray]

Follow-up on this. I did the IOD test and had 28 mA current. So it looks like I don't have a drain. I got a new battery (Northstar deep cycle AGM) and now the charger behaves itself. Looks like it was just that the Optima was draining really quickly. What's weird is that it tested ok. But that's the only conclusion I can come to. Once the weather here straightens up, I'll take it for a drive. Thanks for the great help!

[Steve-Indy]

Glad to hear the issue has been solved !!