Sporadic dead battery out of the blue

ThikStik

My sleep apnea is winning
Good battery and charging system. Can go for months and be ok, then overnight, battery is totally dead. Years ago I would be woken up by the fan turning on. (freakin poltergeist) So I disconnected fan delay relay. I double checked that it is still undone, and it is. Can the power antennae do this, even tho it functions ok ? It must be a strong drain. Thanks all.
 

turbo nasty

Turbo Dojo / MNTR
ECM, Alarm and radio is a few parasitic drains.

You stated the battery and charging system are fine...How were they tested?
 

jlat

Well-Known Member
hello; What's happened to me in the past is is the brake pedal switch gets stuck on leaving the bat. dead in the morning.
IBBY
 

fastblackracing

Well-Known Member
Good battery and charging system. Can go for months and be ok, then overnight, battery is totally dead. Years ago I would be woken up by the fan turning on. (freakin poltergeist) So I disconnected fan delay relay. I double checked that it is still undone, and it is. Can the power antennae do this, even tho it functions ok ? It must be a strong drain. Thanks all.
You will need to get an ampmeter and temporary install it for testing purposes only. Unhook one of the battery cables and hook one lead to the battery and the other lead to the battery cable you unhooked. With every thing off, doors closed, etc.. you can see the amp draw, there will be a small amount for the ecm, alarms and such but you are looking for something pulling a couple of amps or higher since its going dead over night. If you catch it doing this you can pull fuses one at a time or disconnect components and retest to narrow it down to a particular circuit. Its not as hard as it sounds<just trying to give you some detail. Let me know if you need more help.
 

turbo nasty

Turbo Dojo / MNTR
Another...albeit easier way is to use a clamp on ammeter that has scale for DC. Recently used one on mine with good results.
 

fastblackracing

Well-Known Member
I agree with you turbo nasty, its all in what equipment you have available to use. For me it be good reason to go buy some new tools.
 

ThikStik

My sleep apnea is winning
Turbonasty...It is fine for months, then can do it overnight. Batt is 1 yr old and alt altho not tested, must be doing well to make car work 99% of time. Good advice on ammeter, but im gonna take a lazier route and just hope it starts doing it more, and packing some jumper cables (ghetto). My biggest problem is a (no problem found) scenario , as it is so rare when it does it. Yes, its gotta be a draw in the 1-3 amp territory to take it down in a night. I suspect radio antennae some, but it seems if that was happening, seems it would burn up the mast motor. Maybe a fan turning on or an internal alternator drain? I need a priest, alot of other weird things happn!
Thanks
 

coldair85GN

fast85GN
I used a clamp on DC ammeter with my truck a few months ago to figure out a constant battery drain issue and I discovered that my aftermarket head unit was drawing unbelievable current on the memory lead (this happened in my truck AND my other car..which both had identical head units). Turns out this was a known defect on THAT head unit which the manufacturer wouldn't acknowledge although they quietly discontinued the stereo. You could use a clamp on ammeter on either the positive or negative battery terminal...power down the car completely...and then one by one pull fuses from the fusebox OR disconnect any hardwired items you may have until your current draw goes away. RANDOM electrical problems are a pain in the ass to troubleshoot on cars.
 

ThikStik

My sleep apnea is winning
Interesting. My head unit is the old 1987 delco radio. Now it does have a new problem. It attenuates too soon .that speaker saving feature thats built in. It does it sometimes, and not at other times.
 

coldair85GN

fast85GN
I doubt its the radio but if you want to make sure....pull the fuse or disconnect it for a few days and see if the problem goes away. You haven't mentioned anything about other variables....such as wet or dry weather? My 85GN has the electronic climate control system and I recall a few times when I washed my car and got water near the electrical connections by the HVAC and noticed that the blower motor would run...until the connections dried (water creating a path of electrical flow to the blower motor). If your antenna were running constantly I'm sure you would be able to hear it...and by now Im sure it would have stopped working. What electrical mods or electronics have been added to the car (guages, fuel pump hotwire kit, it could be something you would never think about...anything thats been spiced into the wiring COULD possibly cause it...and YES....if the radiator fan were coming on...that would totally kill the battery in short time).
 

ThikStik

My sleep apnea is winning
Thanks. Its garaged and hasnt rained. Antennae still works, so its not shot. Hotwire is only mod. I do have gauge but not an ammeter. Wiring is in good shape generally. I know how to uses ammeter, its just gonna have to start messing up to ever diagnose. Im thinking fan... I am going to pull it into house so as to hear if fan comes on at 3-4: am when the poltergeist are peaking. Wish I was kidding about that...another story.
 

GullsGN

OLD HIPPIE
Thanks. Its garaged and hasnt rained. Antennae still works, so its not shot. Hotwire is only mod. I do have gauge but not an ammeter. Wiring is in good shape generally. I know how to uses ammeter, its just gonna have to start messing up to ever diagnose. Im thinking fan... I am going to pull it into house so as to hear if fan comes on at 3-4: am when the poltergeist are peaking. Wish I was kidding about that...another story.
Feel the light bulb for the trunk and under the hood to make sure they are not staying on. Been there, done that!
 

cdsttype

Member
I WOULD DISCONNECT THE ANTENNA THEY WILL STILL WORK AND RANDOMLY CAUSE A
DRAW JUST PUT IT UP THE DISCONNECT AND SEE IF THE PROBLEM GOES AWAY
 

ThikStik

My sleep apnea is winning
It hasnt drained down once since my posting about it, and it has been doing alot of sitting. I adjusted the driv side door awhile back, and it doesnt always shut unless theres some oomph behind it when u close it. This stopped all wind noise and cleaned up some body gaps from GM, but sure enough, when this happens, its enough to leave the dome/courtesy lights on. So this is probably what happened. KISS principle perhaps, but watch the fan come on next week at 3:47 AM out of the blue like a ghost...lol. Thanks for the replies.
 

HelloBozos

A Bozo in Buick
Tried replacing the cigarette lighter? Alot of Radar detector use spin's them in place an shorts the orange wire behind it.

Or like others said, your burning an blub all night or for weeks somewhere.,trunk,under hood,map light, etc,etc..
 

ThikStik

My sleep apnea is winning
Shouldnt be cig lighter, that'd be a dead short thereby immediately blowing fuse. Am pretty sure it was scenario with the door switch, but there's always tommorow.
 

EVIL

BANNED FOREVER
My battery was draining and i couldn't figure it out. After having a local alternator repair shop test the alternator and the battery ( under load ) and they were fine I came on here.

The easiest way to test for a drain that I was told was to disconnect the positive cable from the battery and put a test light between the battery and the cable. Make sure everything is off and doors are closed. If light comes on there is a drain.

Then pull the fuses one by one until the light goes off. Then you'll know what's causing it. My problem was the after market radio.

D
 
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