IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: Dont Panic on July 23 2012, 06:21:20 PM
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Hi,
I have another question for the tech gurus. My battery will slowly die if the car is not started for a couple of weeks. I have no current draw, other than the computer which is pulling 110mA. Is this the normal draw for the computer?
Thanks,
Devon
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Sounds like you have something drawing more than it should. I am no expert but have a nice little face tube link for you.
http://www.youtube.com/watch?v=KF1gijj03_0&feature=g-vrec&context=G22afde6RVAAAAAAAABw
The movie mentions that the draw should be no more than 55ma.
You have an aftermarket stereo? If so then that would be the first place to look. Or start unplugging relays and see if that cuts down on the draw?
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is that right after you connect your meter in series with the cable, or ten minutes or so later.
It depends on alarms, radio, ecm, etc, but I would think it should be closer to 50 ma after a bit of time has passed.
Going down in a couple of weeks sounds more like a battery with a weak cell to me-assuming the delay fan relay has been unplugged so it cannot suddenly wake up and run the fan for a bit
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by the way, I am not a guru....I sometimes play one on the net tho....otherwi se you would find me at Tim Hortons eating donuts
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Ouch Steve :)
remembering-
This is a Tbird and not a GM so body drains may be a bit different.
15-150 ma longterm doesn't sound unreasonable.
I'm not an expert but I go to Tim Hortons- cuz you need 3 Daves to make a GN Quorum.
clock in the car? body computer? anything not switched -alky, scanmaster....
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Tim Hortons, I love that place. I swear they put crack in the coffee it is, so freaking good.
Too bad there isn't one local to me. :-[
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My 87 T sits for over a month at a time between getting started - and the battery is fine.. Odd..
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Long as draw is low and you have a good battery you can leave it for long periods like that.
Anything longer probably best to put a tender on it.
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My seat of the pants calc is that after two weeks at 100ma you have used about half the capacity of a typical car battery. I'd start to worry about starting after that so disconnect for any longer periods?
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This has some draw numbers and look period correct-ish.
http://flashoffroad.com/electrical/CurrentDrain/currentdrain.pdf (http://flashoffroad.com/electrical/CurrentDrain/currentdrain.pdf)
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just remember to wait a minute or so to read the meter so the initial surge has settled down
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Thanks for the replies. I did not wait much time when I checked it. I will check again and wait a few minutes.
The 110 mA was the draw from the engine wiring harness alone. The engine harness is separate from the car harness on this car. The amount of draw when I disconnect the fuse going to the computer is low to nill. I can`t remember exactly what it was, but next to nothing. I would think that the computer would be using a few mA to maintain power to the chip, but that should be it. Is there anything else in the engine bay that requires power with the key off?
Maybe I have a short somewhere. I saw the Eric The Car Guy video the other week. It lead to me checking this. Unfortunately I have an entire engine harness to look through. I will need to get one of those current testers (used in the video) and try to find the current draw with the key off.
This draw might also be related to my low BLM issue.
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I would not think so, but, a lot of stuff I have thought has turned out to be less than true!
Alarm system and radio memory are the normal culprits. Hard to have a short that weak, I would believe
What is this engine in?
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It is in an 87 Thunderbird Turbocoupe. There are no aftermarket stereos, or alarms. There is next to no draw when I disconnect the ecm fuse.
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Borrow another known good ecm and see if it still has the same high draw. I would do this first.
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Yep, that sounds like the winning idea.
Now, for clarification, do you have a Buick transplant, or is this another car with a problem. No need for me to disconnect a buick to check for current draw if this is a ford pcm. :D
This is not an excessive amperage draw for some cars and a good battery should be good for at least a month
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It is the buick transplant, buick computer and a homemade stand alone GN wiring harness that was put together following the GN wiring diagrams. If you can check your current draw that would be awesome. How would you check it, with and without the ECM fuse connected?
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ammeter between negative post and cable
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Devon I should also have a spare ECM if the time comes you need one to try one for testing.
Your gonna be buying the first round when we go for a beer tho!! :player:
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I know I have a spare or two myself. Probably 3 ecm`s in total. I used to pick them up at the scrap yards back in the day. I sent them off to storage last week though (2.5 hour drive away). I am pretty sure it is not an ecm problem as I have run the car with multiple ecms and the battery has always drained. Dave, thanks for the parts offer again, you have been a big help!
Steve,
I think I would need two readings for a comparison. One with everything connected, and one with the ecm fuse disconnected. This would give me a better idea of the draw from the GN engine harness / ECM combo (1st reading minus the 2nd).
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I am 70 years old and don't crawl in floor boards to unplug fuses unless I absolutely have to! :D
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Starts at 140 ma and drops to about 6 ma in a few seconds...gues sing that is radio and ecm.
My advice is to leave the battery disconnected and put a battery tender or one of the more modern units on it to keep it from going bad.
You can unplug the the orange memory wire if you want to separate the ecm from the rest. The ecm-ign fuse is separated from the battery by the ignition switch.
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http://www.harborfreight.com/automatic-battery-float-charger-42292.html (http://www.harborfreight.com/automatic-battery-float-charger-42292.html)
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I prefer the ctek over the battery tender but both will do a good job and I have both of them. The main thing is to not use one that puts out a continuous charge as these can damage a battery over a long period of time.
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on sale Devon:
http://www.canadiantire.ca/AST/browse/4/Auto/BatteryChargersAccessories/BatteryChargers/PRD~0111522P/CTEK%2BMulti-use%2B3300%2B3.3A%2BBattery%2BCharger.jsp (http://www.canadiantire.ca/AST/browse/4/Auto/BatteryChargersAccessories/BatteryChargers/PRD~0111522P/CTEK%2BMulti-use%2B3300%2B3.3A%2BBattery%2BCharger.jsp)
I use two.
Dave