Parasitic draw or bad battery

Been wondering if I have a parasitic draw or battery going bad in my Diplomat AHB. Battery runs down way to quick after sitting just a week to ten days in the garage. It's a big Interstate just over three years old. I finally got around to pulling negative cable and checking with multi-meter, and shows 60 milliamps. I thought this was kind of a lot, but wasn't sure, so I pulled every single fuse, and NO change.

Battery going bad? Am I missing something? I pulled every fuse. Is 60 Ma unusual necessarily?

Thanks.

Larry

Ensure you have everything turned off, map lights etc. if you have a newer vehicle with an ECM etc. you will need to let it "time out" or "go to sleep" for testing the draw, this includes ensuring your door is closed (no draw from a dome light, under hood light etc.)
Disconnect the negative battery terminal, now make that connection by hooking an ammeter between the batteries negative terminal and the disconnected battery cable end.
This will tell you the draw.
You can pull fuses and disconnect things until you find the suspect circuit. Then you will know if you have an excessive draw.

Disconnect the alternator and check it again.

Kevin

Okay, will do. So are you saying 60Ma could be normal, and should always test with alternator disconnected, or that alternator might be bad (bad diode)?. I'm going to test with it disconnected, just wondering what to conclude afterward. If no change and still 60Ma then what? Or, if significant drop? Thanks, Larry.

Feel the alt.& see if its warm,alts.can draw on a battery when there's an internal fault.

Okay will do. It was really strange that the meter never moved even a tiny bit when I pulled any of the fuses. Thanks! Larry

when disconnecting the neg.batt. terminal to connect a DVOM you have to hold the leeds against the terminals if it disconnects & goes open the vehi.wakes up again {on newer cars} & you have to wait for it to go to sleep again.

Parasitic Draw

Dodge Diplomat AHB. '89. I had help so leads were secure. Had to have help so I could pull fuses one by one.

what does the battery voltage measure just sitting there?
I ran into the same question and then remembered that a battery going bad isn't going to have a high resting voltage like a new one.
the battery was 12.5 volts. vs the normal 13.5 you would expect.
I even ran it on a charger for a while and it came back down to the 12.5 volts after just sitting.

I've had a lot of bad batteries the last few years. Some even loose their charge being disconnected. Others being connected even the smallest load like what the clock memory draws is enough to make a difference even if the battery holds a charge when it's disconnected.

If you have the ignition switch light make sure that goes off. That stopped timing out on a friends car. Unless there's something aftermarket the only real stuff on an M to cause drains is problems with the radio, ignition module, or a light that's not going out. Or the alternator thing that was mentioned altho I've never personally seen that problem.

I wouldn't expect a 13.5V reading on a battery. 12.6v is fully charged. 12.5v isn't bad at all.

https://haynes.com/en-us/tips-tutorials/how-test-car-battery-multimeter

I thought about the ignition light but either it's burned out or disabled due to AHB. Factory radio so minimal draw there. As you mention, not much on M bodies. I'm going to test again with alternator disconnected. I did leave negative cable disconnected yesterday after testing, just to see if that changes anything. I probably won't have a chance to get back to testing it again for a week or so anyway.

Gonna add rear window defrost to list.

Also, forgive me,but I've noticed in a lot of your post you feel to follow diplomat with AHB or AFB why is that?

AHB means cop spec, lots of differences between the cop and civilian spec M bodies.

Yessir and that will drain a good battery. If pulling the fues didn't identify the culprit then it is something likely connected all the time, IE: alternator as suggested, starter, starter relay (doubtful), ignition switch or wiring in the column. Has to be something that is non fused (box wise) and connected to the battery when the switch is off. I had one that drove us nuts for a bit, it was the clock motor that wound the spring. The clock didn't work so I didn't think to looks at it. However the points that open when the spring is wound were stuck shut thereby energizing the clock motor 24/7. Can't remeber the draw but it was 30ma + I think, Happy hunting and do keep up posted )

Thanks for reply. I'm going to first try disconnecting alternator. Hope that's it, because I actually have a spare taking up room.

When you first take a battery off the charger you will have a "surface charge" which is really fake news for voltage. Do something like turn the headlights on for a second then back off and you will see the actual voltage after that. A fully charged 12V battery at rest should be 12.65-12.75 at rest. Even as low as 12.3 is significantly discharged and has a big effect on the output capability.

The alternator is a good place to check like mentioned before. It sure is frustrating when the item that charges the battery also discharges it.

If you have an aftermarket voltage gauge installed, it could be that as well. I had one it my Powerwagon, that would discharge the battery enough in a week, it wouldn't turn over. Not sure why a gauge would do that, but it did.

Good suggestion It did that because it is supposed to be hooked up to a "switched" source meaning it turns off with the ignition switch or it will continue to draw current and drain the battery. We have seen that issue a couple of times ourselves

Thanks for info. Hope to play with it tomorrow. I don't have a single aftermarket install, except FiTech EFI, right to battery, and I disconnected that before testing.

It does have factory spotlight, which I don't know if is fused. Maybe inline fuse? I haven't followed the wiring for that which I suppose runs into a factory police harness which could be fused to one of the ones labeled "accessories" and I pulled every fuse when testing. But I would certainly notice if the spotlight was coming on/off at times.

could it be possible the wiring in the pillar the spot light goes through may have the insulation cracking and just a strand or two touching the through tube causing a drain ?
just thinking out loud here.

Quick and dirty. Disconnect the negative battery cable. Install a test light between the negative post and the removed cable. If there is a IOD (ignition off draw) the lamp will light. Don't be surprised if it lights. Give it 15 minutes and see if everything goes to sleep. the light should go out. If it does there is no draw.
Doug

Thought the test was done the same way, but with negative cable. Or would it really matter much because the light is completing the circuit?

Either cable. We actually use a shunt at work. A shunt place in series between the battery and cable can show amp draw on a digital volt meter. You can also use an amp meter. But the problem is you may blow the milliamp fuse in the meter if the draw exceeds the fuse limit.
Doug

The fuse in most ammeters is 10A, if you have more than a 10A parasitic draw something is seriously wrong.

The face of your meter ought to be labeled for max current in ammeter mode.

Making the current measure can be tricky.

sample quote

You are using the amp meter the right way, but there is a problem you need to be aware of. Starting in the mid 1990's, most vehicles have at least one computer that needs up to twenty minutes to go to "sleep" mode. During that twenty minutes it can draw up to three amps. Logic would dictate you just have to wait for more than twenty minutes, then start the testing, but there is one more piece to the story. Anything you do to remove power to that computer, even for just a fraction of a second, wakes it up again, and then you have to wait another twenty minutes for it to go to sleep. Once the battery cable is removed, as soon as you connect the final meter lead, the computer will wake up and draw high current.

Most of the common, inexpensive volt/ohm/amp meters have an internal 2-amp fuse for the milliamps and 2-amp range, and they need to have the positive test lead moved to a special jack to use the 10-amp range. That 10-amp jack is rarely fused.

Most people will start the testing with the meter on the 10-amp range, then they can read that 3-amp drain until the computer goes to sleep. Once that happens, we need to switch to a lower range for more accuracy. That means removing the test lead from the 10-amp jack and moving it to the common volts/ohms/milliamps jack. Doing that breaks the circuit, and once reconnected, the computer will draw enough current to blow the meter's internal 2-amp fuse. "Frog fuzz!" Now the frustration begins.

If you are lucky enough to not blow that fuse, you will be on the 2-amp range, and once the computer goes to sleep, you will probably want to switch to a lower range, again, for more accuracy. All voltmeters with a rotary switch use a "break-before-make" switch which means as you slowly rotate the knob, the internal contacts break the connection to one range, then it makes the connection to the next range. That very minute gap is plenty to cause the computer to wake up again. Even if the fuse does not blow, you will get an over-range indication because the computer is drawing much more current than that range can handle.

I am fairly confident this is why you found 2.25 amps of current drain. You may have waited an hour, but you have to wait after making the final meter connection and selecting the range.

There is an easier way though to solve this.

Connect your meter like you did, and start on the 10-amp range. Wait a good twenty minutes or until you see the current drop significantly, then use a small jumper wire to connect the battery cable to the post. You can also jump between the two meter probes. Regardless how you do it, the meter is bypassed, or in effect, shorted out in the circuit. Voltage to the computer has never been lost and you are free to move the meter's probe to the milliamps jack. When you are ready, remove the jumper wire and read the meter.

If you see the current has dropped low enough to warrant switching to a lower range, put the jumper wire back on first, then switch the range. When you remove the jumper wire again, current will have no choice but to go through the meter to get measured.

Unless specified differently by the manufacturer, the industry standard is you're allowed up to 35 ma. (.035A), of current drain to keep all the computer memories alive. Chrysler says at that rate, a good, fully-charged battery will be able to crank an engine fast enough to start after sitting for three weeks. Cadillac is one brand I am aware of that allows up to 50 ma.

end quote

from

https://www.2carpros.com/questions/parasitic-drain-caused-by-altenater-diodes

This also explains why using a shunt to measure the DC current may be preferable.

Not even applicable to the OP's ride.

Nothing to go to sleep on my ride for sure. I'm sure there's a draw via the way tested. Then I left negative cable disconnected for several days, then connected charger to battery and it was still at 100%

I'm starting to wonder more about the spotlight. I want to dig into the dash a bit anyway because one or both of front speakers is crackling and annoying me, so I'm going to dig in a bit and follow that factory spotlight wiring and see where it leads. I've had everything out before to bare firewall, and just can't remember now, and whether there's inline fuse. I still need to test alternator too. I got busy with damn wiper grommets and putting linkages back on (and cutting up my arms) and didn't finish as quickly as anticipated

Is larry not lovin it anymore ?

I seem to remember someone offering you a reasonable sum of $$ to take that PITA off ur hands

with an older vehicle and an undiscovered milliamp level electrical fault,
use your eyes to look all over for “Green Death” corrosion deposits,
that horrible blue-green-grey colored stuff.

If you cannot find it with regular white light
sometimes using the Ultra-Violet flashlights that come with Freon leak spotting dye
in a totally dark garage will make Green Death glow faintly.

As a Christmas present I was just given a
Sharper Image Travel UV-C Sanitizing Wand
Item No 205847
that has a 4 watt UV-C tube
and an internal mercury switch that turns itself off it the light is not shined away from your eyes.

https://www.sharperimage.com/view/product/Travel+UV+Sanitizing+Wand/205847

It is way brighter than my UV freon dye flashlight
or my Hunter’s urine/blood spotting UV flashlight.

If you suspect the spotlight,
and do not want to tear into the dash
begin by disconnecting the two battery cables
remove the bulb from the spotlight
and use a good meter to measure resistance in Ohms
from positive + bulb socket contact pad to black - battery cable.

Using a “Megger” meter hand cranked at a higher voltage than the 9 volts of the typical multimeter would be even better.

https://www.youtube.com/watch?v=t0k8MnJzM_g

https://www.youtube.com/watch?v=WpANiRvB4tE

Using a megger is a good way to blow up any electronics. I would pass on that. Granted the M body in question doesn't have as much electronics as later model stuff but odds are good his Fitech and radio would be kaput unless isolated.

Odds are pretty good there is a disconnect in the kick -panel to unplug the spotlight.

When using the amp meter at the time the test is started we use a second cable run in parallel to the meter. That way any current flowing when modules go to sleep is uninterrupted. Start on the 10 amp scale and remove one end of the jumper. Read the scale. If the draw is low enough reconnect the jumper. Switch the meter to the lower scale. Now remove the jumper. This is why we use a calibrated shunt. Everything stays connected. You just read the millavolt scale on the meter I also find it helpful to latch the door latches. Or in the case of an older car remove the dome fuse or plunger switch. That way you can test with the doors open. I do these tests often. I work in prototype debug at FCA. It’s amazing what will cause an issue. Many times it gets down to removing fuses, modules, switches one at time waiting and watching. Can be very time consuming on the new stuff.
Doug

Oh yes, I was certainly advocating using the 4000 volt setting on the the Biddle, not the 20 volt.

My favorite setting is the 1000 volt setting,
which will bring earthworms up out of the lawn.

I have been working a lot and been trying to finish PITA job of replacing wiper linkage grommets and then put the linkage back on, clock the motor just right and attach to motor. I got it all back together, and wiper motor worked for a second then stopped. Now it's working intermittently (not in the way intermittent wipers are supposed to). I played with harness, cleaned connections, jiggled wires and tapped on motor with hammer. Only once did the motor start up again, and that was when jiggling wires. I'm wondering if wiper motor is the issue. I did pull that fuse when doing the testing so it should have dropped the amp draw on meter then, but I guess the draw could be intermittent. So next is fiddle with that motor and see if disconnecting changes draw, and still need to test alternator.

Remember, '89 Diplomat so not any modules to go to sleep. Also I did disconnect the FiTech power when testing the first time. I disconnected dome light plunger the first time testing, drivers door open, me at fuses, my brother at battery.

And I will be pulling the dash soon anyway to access front speakers, and I'll follow the spotlight wire and disconnect where I can.

The lowest voltage I have seen a megger test at is 100v. which will pop a car's electronics.

One could also disconnect the wiper motor to see if the draw goes away (kwik and dirty )
If you know where the SL wiring is, does it have 1 or two wires? If only 1 that would be power and the ground path would be though the s/l mounting. Isolating is would open the circuit. One could also cut the wiring (I wouldn't want to either). I kind of doubt it's the S/L myself. BUT ????
I'm assuming you completely disconnected the alternator with no change ?
The only other items I can think of are: glove box, trunk, under hood lites, But then being an ex cop car it could be a left over energized relay that is not hooked to anything. Keep us posted

Don't think this is the answer, but try adding a ground wire to your wiper motor.
I had to do this on my '89 D250, for some reason case wasn't grounding and motor wouldn't work.

I don't want to dogpile about using a megger but frankly I can't see what value it would be even if it could be used. Meggers are used to stress insulation to determine its condition. Using it in this case wouldn't provide any additional information over what a VOM would give. As to the problem, wow, even Hitler couldn't win with two fronts. Either get the wipers squared away or the leakage squared away. As to finding the leakage, make a copy of the wiring diagram from the FSM. Highlight the positive side of any feeders to individual components. Then start isolating them one by one. I have been down this road more than once and as shotgunning may be good for pheasants, it isn't for electrical troubleshooting.

I was also going to mention adding a ground to wiper motor like geo said. I had to do that to my 1988. You can even test it by using jumper cable or any wire to go from a good ground to the case to see if it starts working.

If it' hasn't been said yet one quick way of pinpointing the circuit is to pull one fuse at a time and check with a meter there instead of at the battery.

Spot light wiring was a good idea too. The wire for them usually runs loosely inside the pillar cover and can easily get pinched or rubbed with a screw.

Yes spotlight is one wire down into the dash somewhere and I'm pulling dash for speakers anyway.

Okay, ground wiper motor. Right now it's disconnected as car sits a couple days to see what happens when I can get back to it.

I've gone all around it in dark garage multiple times looking for any light. When this first started I thought for sure the ignition key light was going to be stuck on but not that. Not trunk, underhood, dome, ash receiver, or glove box lights.

Does the car have a clock ? working or not?

Also being an ex cop car it could be a left over energized relay that is not hooked to anything. Do you have any relays that are still in place ?

Also I would use that DVM hooked up in series (reading the draw) all the time when you are testing.

Alligator clips and test leads with clips are handy for jumpers and are cheap. the test leas also won't handle a lot of currrent so they can act as a fusible link as well AMHIK LOL

I’m sure it’s been said, but you also want to feel around for anything warm, especially under the dash.

Actually, I don't recall reading that. I'll feel around when I take dash pad and lower panels off. Feel the alternator for warmth was suggested.

I've had the car for many, many years and the problem just started within the last year or so, so anything left energized should've presented itself already (I would think). Wig wag headlights are still connected and I already eliminated those when I did testing. There's a connecter ((not just wires) hanging right under front bumper that was probably lights or siren. I can check that for energy too but it's been there from day one. I've never followed it all the way back. I just cable tied it up years ago.

The clock is built into stock radio and that draw has got to be so minimal. One thing I've been thinking about is that it is one of the first air bag cars. I'm sure that's fused, and I pulled every fuse. Just trying to think if that could be the issue. "Air bag" light does come on while it inflates for ten seconds or so when car is started. I really just need to get back to testing alternator, then pulling dash before I speculate more I guess.

It appears to have been the alternator. To sum things up, my '89 Diplomat AHB had a 60 milliamp draw, and it wouldn't start after sitting couple weeks. I went through pulling every fuse, draw didn't change. Disconnected alternator, let car sit, battery stayed fully charged. Wanted to use voltmeter with alternator disconnected, but the batteries in meter leaked out and ruined it. Ordered another from Amazon. While waiting, I installed another alternator I had, slightly used but from another Dip Police car so perfect match. Left it connect along with battery for a week. Threw charger on battery, and it was fully charged. New voltmeter arrived, and it shows 140 milliamp draw! WTH?! Yes, it was on right settings, I confirmed. Doesn't make sense! Battery would have gone dead in a week with that kind of draw. It was almost dead with the 60 milliamp draw after that long.

Drove the car around for quite awhile last night, so headlights on of course, plenty of brake lights, radio on, other accessories. Came home, threw the charger on battery, and it was fully charged. I think I got a bad voltmeter. Probably Chinese junk. It was only $15 but had good reviews. Maybe some were fake. All seems well now. Btw, the bad alternator never got warm.

Story - My not too smart sister bought a 1983 Renault Fuego new. Around 86/87, in cold weather the battery would be completely dead in the morning. Not very good mechanic charged her to replace the almost new battery. Did not fix it.

I troubleshot it to a bad diode that was shorting out in cold weather and would turn everything on the aux circuit in the middle of the night and hence dead battery in the morning. She bought it at Papa's Dodge (and others back then) and I was there buying parts and inquired about the weird alternator problem. Was told its a common issue with those cars. Seriously?

So she buys a new alternator. Starts getting warm out so problem stops and she doesn't replace the alternator. Fast forward to next winter - problem reappears. So I put the alternator in. Within days the brush assembly burns up. Can't remember if alt was still under warranty, but go back to the dealer where she bought it. No longer available. Seriously? This is now about 1987 or 1988, and they sold these cars in the USA thru 1986. No alt to be had. My dad the great machinist that he was, made a set of brush holders. Thing of beauty. Burn up in several days.

I stick a Mopar alternator and voltage regulator in it. Even made a voltage sensing circuit to interface with the Renault idiot light.

A few years later she buys a new car. I said whew - it's out of my hair. Nope - she gives the car to my other sister. Couple years later the car burns down from an electrical fire. That car was an utter POS............ That was not the only electrical issue I had to deal with in that car. Plus many other issues.

Mark is 100% right that electrical components can be temperature sensitive. When I worked at Intel, more than once I watched parts consistently pass at 125C and the same part(s) consistently fail at 127C. That's about 3 degrees F different.

yes, ..... temperature, temperature, temperature !
cold out, won't start, put in warm garage for just a little bit, starts right up and nary a problem can be found !
unfortunately, not too many troubleshooters like to work in zero degree temperatures.

New lithium battery installed. So odd to hold a car battery in one hand without any problem. As you can see much smaller than the original battery. I had to trim the Thermoguard about an inch and a half on the bottom to make it fit as it’s much smaller. Way more cranking power than Megatron Interstate that I had at almost a quarter of the weight (11 lbs).

That looks impressive.
I am really interested in shaving off weight.
But...the fearful thought pops into my head...What kind of violent hot fire would that Li battery create if vibration causes its internal parts to short out?

My brother-in-law bought me an expensive Li battery jump starter for Christmas one year ago.
I am afraid of carrying it in the vehicle,
although I have pulled dud explosives out of boreholes, parachuted, landed a plane whose engine missfired and blew an exhaust manifold right through the engine cowling, worked on live 69 kV equipment, worked alone while “Fire Bossing coal mines, rafted down dozens of Class V+ rapids, etc, etc

What battery model is that?

something that looks odd in your picture is the terminal ends.
it has to do with the space, or lack thereof, between the ears of the cable ends.
knowing a person only needs to tighten the terminals snugly so they don't rotate, i have found terminals that do not have at least 1/8" gap between the ears have a tendency to not contact the post surface entirely, allowing air space [however minutely] between the terminal and post to possibly create corrosion in the future.
also, the negative post looks to be sitting somewhat proud of the post top. using a set of battery terminal spreading pliers would help the fit of that.
not trying to nit pic, just observing a couple of things that have caused me corrosion issues over the years.

I assume you will need a special battery charger?

Braille group 34

Yes, I have to spread the negative more, I know, but thank you. I tried to split it open more with a flat screwdriver (all I have) but it wouldn't split more, and just would not go down any further on the new post. I was anxious to get it hooked up, so that was just for now, but I definitely wanted it lower. Thanks again. Larry

Yes, I worked a deal and they threw the charger in on the deal. It's not much bigger than a big smart phone and probably weighs less.

don't do like my brother did one time.
he bought a new battery for [i don't remember what].
the one cable didn't go down far enough, so he [GUESS WHAT ? ] pounds on it with a hammer, thereby "kinda" sinking the post into the battery, breaking the case along the way.
he took it back to the store and told them "i don't know what happened ?"...........
when he got back with the "new" new battery, i introduced him to the battery spreading tool...............
every now and then, that story pops up between us.

Oh no definitely not. I tapped on it lightly with a rubber mallet to see if it was loose enough and stopped right there! I don't even like when I'm tightening down a battery terminal and it pulls on the post in one direction. I always try and counter it by pushing on the side of bolt.

i tighten the terminal until snug feeling with the wrench, then a tick more until i can't rotate the terminal by hand.
i also use some kind of dielectric compound on the post and terminal to stop any kind of corrosion caused by out-gassing of the battery.
if i have any of those red and green felt post washers around, i use them with the dielectric compound.
another trick i have used over the years, and it flat out WORKS, is a light spray of wd-40 on the posts and terminals. wipe off the top of the case when done just because.
the wd-40 works as good, and i think BETTER, than those battery sprays and greases available, plus there is no MESS to contend with if you have to disconnect the battery for whatever reason.

Thanks for tips. I'm pretty sure these sealed Lithium batteries will not of any out gassing.

Sign of the times. Got my new voltmeter and it indicated draw of 168mA!!! This is after I swapped out alternators, and battery stopped dying after car sat for couple weeks. It was only showing a 60-67mA draw with my other meter before the batteries leaked out and ruined the meter. Finally got another meter, although the car has been fine, and I felt certain I already found the problem to be the alternator. Sure enough, new, new meter shows 30mA draw, old, new meter still showing 168mA draw (yes, I'm sure dial settings are right). Typical POS right out of the box. So frustrating. So confirmed it was the alternator, and confirmed so much new stuff is junk, and certain not to be getting any better soon.

lol, when it rains it pours. If i was close by I'd come over with my Flukes and help sort it out with you.

Some times cheap tools are more expensive than a good tool.

Thanks. I'm certain I got it sorted out now with the alternator replacement. Frustrating though because now you can't count on new part being good, and have to wonder if it's bad too, or if that wasn't problem in the first place.