Battery Going Dead, Key OFF Current Draw?

GNDriven

Active Member
So the issue is the battery goes dead overnight after spending a few hours on the charger.
I placed a current meter in series with the negative side of battery to measure the current draw with the key off. I am getting 0.170 amps consistently. When the key is turned ON, but not cranking it jumps to 1.6 amps. I am trying to get an idea of what is a normal current draw with the key off, to see if I do have a drain on the battery. Can anyone tell me what your car draws in current from the battery when the key is off?

If 0.170 amps is high, then what is a good approach of finding the issue? Do I start unplugging the wiring harness until the current drops or what? Thanks
 

Blazer406

Mechanical Engineer
I would think you normally would have zero amps drawing unless you have a digital clock that stays on on the radio?

I would have suggested stuck FP replay, but you could hear that... and it probably draws more than .17 amps.

start pulling one fuse at a time and see if you can get the ammeter to drop out.....
 

Mark E.

Member
Usual rule of thumb is less than .1 amp (100ma)

My cars measure around .02a (20ma)

Try the fuse trick. Also the fan delay relay.

Good luck, Mark
 

GNDriven

Active Member
Thanks, yea just read about the fuse trick described by pulling fuses one at a time until the current drops, then seeing what circuits that fuses services. Also I misspoke the current goes too 1.6 amps when the door opens not when the key is turned on.
 

NyBlankets

Active Member
"Also the fan delay relay."
Mark could be right, I had the same problem and it turned out to be the fan delay relay.
 

GNDriven

Active Member
OK good ones. I guess all things electric are suspect :(. Im hoping its not the starter or anything deep in the harness.
 

charlief1

RIP Charlie!
Thanks, yea just read about the fuse trick described by pulling fuses one at a time until the current drops, then seeing what circuits that fuses services. Also I misspoke the current goes too 1.6 amps when the door opens not when the key is turned on.
If you don't get results by pulling the fuses you can take a test light, disconnect the negative cable, and put the light in between the cable and battery. If it lights up then you start unplugging different items like the alternator and under hood/trunk light. I suggest that you do this indoors so the light will be seen easier. Sometimes it will just barely glow and in full daylight you won't see it. Good luck.;)
 

turbotod

New Member
I also have a current draw with key off found it to be the single wire going to the top of the alternater. I don't know why this would stay powered after the key is off.I wonder if a relay is stuck. Hope this helps
 

turbojoes

Member
Just started to eliminate things that would draw power with key off and it ended up being the trunk light. Pulled the bulb out and then checked the battery a while later and it never lost any amps.
 

dvernst

Well-Known Member
I had an old AC delco CD player in my car that was drawing power also. When I would hit eject after the CD was out it kept drawing power. If there was a disc in it it was fine.
 

jimmymack87gn

Boost Junkie
There is a mathmatical equation based on amp hours & current draw, but keeping it simple if your current draw is less than 30 mA (0.030A) you should be fine. I do know for a fact that 50 mA will discharge a battery in 3-4 days & over 100 mA will typically discharge overnight.
 
C

coach

Guest
I bought a power invertor to run my laptop for my Powerlogger. It was drawing power just being plugged in with nothing plugged into it. It was driving me nuts because it was under the seat and I never thought of it. Finally I unplugged it and charged the battery. Been fine ever since.
 

davelostmissing

Senile Member
There is a mathmatical equation based on amp hours & current draw, but keeping it simple if your current draw is less than 30 mA (0.030A) you should be fine. I do know for a fact that 50 mA will discharge a battery in 3-4 days & over 100 mA will typically discharge overnight.

If your 50-70 amp-hour battery goes flat overnight its time for a new one.
 

groumoutis

Active Member
Does your power antenna go up and down? If the cable inside the antenna is broken it will try to lower the antenna and just keep going. I had this happen on Oldsmobile that I had. I just disconnected the plug that feed the power antenna. You should be able to hear it though.

I would take out the trunk, under the hood, glove compartment light bulb.
 

GNDriven

Active Member
So I was pulling the fuses to see if I could find anything. When I pulled the PWR BRK fuse the current fell to 0.030 amps, which I think is normal. I am guessing this is the powermaster fuse. Anyone have any reason why the circuits associated with this fuse could draw 0.180 amps with the key OFF? Thanks,
 
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