battery drain???
Thread Starter
Intermediate
Joined: Aug 2002
Posts: 36
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From: tyngsboro mass
battery drain???
hi vett people! i am new but have been reading for many years, thanks for all the tips and tricks. i have a 91 L98 coupe.after every 4 days of non-use the battery dies i have checked everything and all is operating correctly, new battery, and everything shuts off when its suposed too. does anyone have any clues as to what is causing this parasitic power drain?? some of you must have run into this problem? any thoughts would be really helpful and greatly appreciated! thank you in advance!!!!!!!!!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: battery drain??? (mtlwiz)
You have not checked everything or you would have found out where the excessive leakage current is going. Remove the negative cable and place an ammeter between the batt terminal and the neg cable and see what the current is after the courtesy lights time out. It should be less than 50 ma. and I am sure you will find it much more than this. You then can remove each fuse and observe if the leakage current drops and isolate the circuit that has the leak. Remove the red wire on the alternator to prove that the diodes in the alternator are not defective. If no leak is found, then you will have to remove the 8 wires on the battery jump terminal by the battery and touch them one at a time to the jump terminal and observe if the leakage current dramatically increases when one is connected. Also, at night, observe if a vanity mirror lamp or underhood lamp is still on. Good luck.
[Modified by jfb, 10:42 AM 8/5/2002]
[Modified by jfb, 10:42 AM 8/5/2002]
Thread Starter
Intermediate
Joined: Aug 2002
Posts: 36
Likes: 0
From: tyngsboro mass
Re: battery drain??? (jfb)
ok guys! not to seem like an idiot because i am very mechanically inclined but my brain stops dead with electrical issues! i have an ohmeter but when i hook it up in series with the neg cable from the battery what setting do i put the meter at? i keep blowing the fuses in the meter and when i touch the probes between the neg cable and the neg term on the battery i get a spark so i am assuming i have the meter set on the wrong thing. any help out there?i am just trying to find a power drain that kills my battery every 4 days of sitting unused.. and yes the battery is fine. thanks
Le Mans Master
Joined: Nov 1999
Posts: 8,512
Likes: 3
From: Memphis, Tn
Re: battery drain??? (mtlwiz)
I have an ohmeter but when i hook it up in series with the neg cable from the battery what setting do i put the meter at? i keep blowing the fuses in the meter and when i touch the probes between the neg cable and the neg term on the battery i get a spark so i am assuming i have the meter set on the wrong thing.
Does your meter have an ammeter setting? It might be marked as "amps". If so, use this setting. Start with the largest setting, usually 10 amps or so. If you don't get a reading, try a lower scale. Hope this helps.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: battery drain??? (mtlwiz)
Your courtesy lights draw a couple of amps, so if you start out the ammeter portion of your VOM (voltmeter, ohmeter, milliameter) on 2000 ma (2A) it may pin the meter and the 10A function requires switching a plug in test prod usually so this interrupts the series connection with the battery and the darn courtesy lights will stay on once again for 30 sec. One thing you could do is set your multimeter to 2000 ma. and short the test prods together until the courtesy lights time out and then unshort the test leads and now you can switch down from 2000 ma to get to the leakage current . Normal leakage current is under 50 ma. My 87 measures 26 ma.
Drifting
Joined: Feb 2000
Posts: 1,994
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From: Charleston, WV
Re: battery drain??? (mtlwiz)
depending on the amount of current draw the 10A setting may not be enough either........... but you could try it at 10A and go lower until you get a good reading........ actually if it were more than 10A I don't think the battery would last 4 days.............. but it might
