Dead Battery
Thread Starter
Cruising
Joined: Dec 2010
Posts: 13
Likes: 0
From: Kansas City Missouri
Dead Battery
Hello Everyone! I have a 98 Vette that goes dead after sitting idle for 4 or 5 days. I've had every relay, fuse and wire checked by 3 different places including a Chevy dealership and I'm told that everything is working fine and there are no draws. The battery that I have now is only 3 months old and has run down totally since my car has been in storage for the past week. Any ideas would be GREATLY appreciated!
Thanks!
Thanks!
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
HOW did they check the current draw???
Theres ALWAYS a current draw. The BCM and PCM are always on. After shutdown they go into sleep/security mode. That correct current draw is specified to be 25 milliamps or less. You usually see 20 ma. That 20 ma draw,, a battery will / should be able to crank the car for greater than a 30 day period. I have seen a fully charged battery easily last 2 months.
When the dealer or shop checked the current draw, the power robber may have not been on.
There are several things that commonly cause this issue. the main on is the drivers seat Make sure that the multifunction switch and lumbar motor on the seat are NOT being left on by accident. Those switches and buttons screw up alot.
Current draw test between the neg battery terinal and batt post:
BC
BC
Theres ALWAYS a current draw. The BCM and PCM are always on. After shutdown they go into sleep/security mode. That correct current draw is specified to be 25 milliamps or less. You usually see 20 ma. That 20 ma draw,, a battery will / should be able to crank the car for greater than a 30 day period. I have seen a fully charged battery easily last 2 months.When the dealer or shop checked the current draw, the power robber may have not been on.
There are several things that commonly cause this issue. the main on is the drivers seat Make sure that the multifunction switch and lumbar motor on the seat are NOT being left on by accident. Those switches and buttons screw up alot.
Current draw test between the neg battery terinal and batt post:
BC
BC
Instructor
Joined: Oct 2010
Posts: 240
Likes: 2
From: Yangpyeong Gyeonggi-Do
Agree with Bill... do the check he is demonstrating. A fully charged operating battery should easily start the car after a month or so of storage. Somewhere in your electrical system you have a battery goblin. Hook up as Bill described and see what you have when everything goes into sleep mode. Bet something is not sleeping! I leave my Radar Detector on all the time and the battery still does not drain as you have indicated. I have started mine after 3 or 4 weeks parked at the airport....never a problem.
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
gdzkid.... fyi... Bill Curlee is the C5 electrical gremlin guru... if anyone can help you track down and solve your problem it is Bill. Bill has helped hundreds on the Forum. If I had your problem, I could not think of a better Christmas present than an email from Bill.
Merry Christmas...
Merry Christmas...
Instructor
Joined: Mar 2009
Posts: 174
Likes: 6
From: Pearl River New York
Bill I'm having the same problem with my 2000 vert, car was sitting for 2-3 weeks and wouldn't start the other day, battery is a new sears gold die hard. i would like to check for any draw, I have a craftsman digital mulimeter and the dc current choices on the meter are 10A and 200m, does it matter which setting I use
Burning Brakes
Joined: Aug 2006
Posts: 1,147
Likes: 18
From: Thompsons Station Tennessee
Hello Everyone! I have a 98 Vette that goes dead after sitting idle for 4 or 5 days. I've had every relay, fuse and wire checked by 3 different places including a Chevy dealership and I'm told that everything is working fine and there are no draws. The battery that I have now is only 3 months old and has run down totally since my car has been in storage for the past week. Any ideas would be GREATLY appreciated!
Thanks!
Thanks!
Racer
Joined: May 2008
Posts: 316
Likes: 0
From: San Deigo California
When you do the current test, BE SURE NEVER TO DISCONNECT THE BATTERY.
When you remove the battery terminal connector, first SECURELY connect a wire from the connector to the battery. I do this by running a screw into the lead battery lug. Keep this wire connected while you hoop up the ammeter. Then disconnect the wire. Do the reverse when removing the meter and reconnecting.
Also I have this same sort of problem on my Chrysler (sorry guys, it's my wife's). The dealership was quoting me over $500 to try to fix it. So now if it sits for more than a week (which is not normal as it is her daily driver) I hook up the charger for a few hours before use.
When you remove the battery terminal connector, first SECURELY connect a wire from the connector to the battery. I do this by running a screw into the lead battery lug. Keep this wire connected while you hoop up the ammeter. Then disconnect the wire. Do the reverse when removing the meter and reconnecting.
Also I have this same sort of problem on my Chrysler (sorry guys, it's my wife's). The dealership was quoting me over $500 to try to fix it. So now if it sits for more than a week (which is not normal as it is her daily driver) I hook up the charger for a few hours before use.
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Instructor
Joined: Oct 2010
Posts: 240
Likes: 2
From: Yangpyeong Gyeonggi-Do
You must disconnect the negative terminal from the battery and place the meter in series with the negative battery lead if you want to read the current draw correctly. Look at Bill's post and pictures.
Pro
Joined: Apr 2008
Posts: 628
Likes: 4
From: Columbia SC
I have experience with three C5s, all low-mile garage-kept cars with new top-line batteries. All three check out fine as to drain MA spec, yet will be down to no-start voltage before a month is out. I doubt that all three have some sort of strange intermittent drain problem, so all of them are now on chargers. Myself, I don't trust tenders or minders or whatever, so I hook mine up each week and let it run until the battery is back to 12.7 volts or so--have encountered several defective "smart chargers" that have overcharged and killed batteries.
Charge your battery up to 12.7 or thereabouts and let it sit for a week. The three C5s I mentioned would take a fully-charged battery down to about 12.3 or so in that week. That's a significant drain but the car will start fine. If your reading after that week is less than 12.2/12.3 volts then you have an abnormal drain from something, assuming your battery is healthy. Good luck
Charge your battery up to 12.7 or thereabouts and let it sit for a week. The three C5s I mentioned would take a fully-charged battery down to about 12.3 or so in that week. That's a significant drain but the car will start fine. If your reading after that week is less than 12.2/12.3 volts then you have an abnormal drain from something, assuming your battery is healthy. Good luck
Melting Slicks
Joined: Jul 2006
Posts: 2,332
Likes: 31
From: Silver Spring MD
Had the C5 in the garage for 2 months and it started right away
When I was unable to use my C5 for over 2 months I thought I might have trouble starting it. Not so. It cranked and started right up after sitting over 2 months without being run. I have a Sams Eveready 78N battery in it and it is still going strong 5 years plus.
Melting Slicks
Joined: Aug 2003
Posts: 2,786
Likes: 7
From: Iowa
its a delicate procedure, if you want to insert the ammeter without disconnecting the battery you will have to use a jumper wire between the negative battery cable and the battery terminal. much easier if you have a dual post battery like the one in the picture. put that wire in place to keep the battery connected, then remove the battery wire and insert the ammeter in series with it, then remove your temporary jumper wire so the ammeter can read the current. you've just added the inline ammeter without ever disconnecting the battery.
no idea if that's really necessary for a good current test, but you never know.
