Battery draining
Thread Starter
1st Gear
Joined: Nov 2015
Posts: 1
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Battery draining
I have a 89 c4 and the battery all the sudden is going dead, tested battery and it is charging, they (Advanced Auto) said I had a bad alternator, so I replaced it. Worked great for almost a week and now it the battery is dead again and had to jump. Any help would be appreciated
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
You need to locate the source of the current drain....
Get a relatively inexpensive Meter, disconnect the battery and measure the current draw between the battery post and the disconnected battery cable - with the car OFF/ Ignition OFF. Typical draw on a C4 is on the order of 20 - 40 milliamps. If you have significantly more than that (which is highly likely or the battery would stay charged for weeks) - disconnect each fuse one at a time and recheck. Find out which circuit is drawing more current than it should. That'll get you in the area of where to look. Not everything on a Vette runs through the fuse box - you'll also need to disconnect the alternator (all connections - not just the output cable) - remember just because you got a rebuilt one - doesn't mean that its right - if one of the diodes in the rectifier is bad - it can draw current and cause a battery to go dead. It's gonna take some time - but you'll find it....
GOOD LUCK !
Get a relatively inexpensive Meter, disconnect the battery and measure the current draw between the battery post and the disconnected battery cable - with the car OFF/ Ignition OFF. Typical draw on a C4 is on the order of 20 - 40 milliamps. If you have significantly more than that (which is highly likely or the battery would stay charged for weeks) - disconnect each fuse one at a time and recheck. Find out which circuit is drawing more current than it should. That'll get you in the area of where to look. Not everything on a Vette runs through the fuse box - you'll also need to disconnect the alternator (all connections - not just the output cable) - remember just because you got a rebuilt one - doesn't mean that its right - if one of the diodes in the rectifier is bad - it can draw current and cause a battery to go dead. It's gonna take some time - but you'll find it....
GOOD LUCK !
Safety Car
Joined: Sep 2004
Posts: 3,953
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From: Mission Viejo CA
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
This is only true after the initial high input current when the timer circuits in the car "wake up" when you re-connect the battery . . . ECM, interior lights, keyless entry, etc. Put a jumper wire in parallel with your multimeter, then wait until the timer circuits "go back to sleep". Then remove the jumper wire without disturbing the connections to the multimeter. If you have keyless entry, remove the battery from the fob to deactivate the system.
If the car isn't allowed to (time out) using a jumper wire you will get a high reading that is not correct..Once the circuits go (back to sleep) you should get a reading "at or below" 50 milliamps which is normal.If your reading is above 50 milliamps it's time to start pulling fuses like mentioned by Purple92..WW
Last edited by WW7; Nov 21, 2015 at 07:30 AM.
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
Some meters will display a number such as .2 which is 200 milliamps. If it displays .02 then you're looking at 20 milliamps. This is easy to confuse especially with inexpensive meters and if you've never done this before. Good luck.
art
art
Instructor
Joined: Sep 2011
Posts: 107
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From: Colorado
I have a 89 c4 and the battery all the sudden is going dead, tested battery and it is charging, they (Advanced Auto) said I had a bad alternator, so I replaced it. Worked great for almost a week and now it the battery is dead again and had to jump. Any help would be appreciated
Bill
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Pro
Joined: Dec 2014
Posts: 530
Likes: 10
One I had on my 1984 were the mercury switches for the under hood lights. A "bubba" fix for that is to add some toggle switches so you can manually turn those lights on and off if the mercury switches are stuck on, or wire across the mercury switches if they are stuck off and use the toggle to turn the lights on and off... Or just replace the mercury switches, I think you can get them from most Corvette parts places...
Pro
Joined: Dec 2014
Posts: 530
Likes: 10
Oh... Another couple suggestions as interim fixes until you can get it sorted out... A battery cut-off like this one:
http://www.ecklerscorvette.com/batte...side-post.html
When you turn off the car, pop the hood and turn the **** and your battery won't drain. also has a great secondary purpose as an anti-theft device. While it won't stop a determined thief it may slow them down a little or make them look for an easier target when the car won't crank.
Or maybe a "battery tender" like this one to keep your battery charged while it is the garage:
http://www.harborfreight.com/automat...ger-42292.html
Not much help if you have to park somewhere without an outlet though. Side advantage is, even a properly working C4 will still run down the battery if left sit long enough. The battery tender will keep the battery charged even if it sits for months like for all the poor schlobs that live in cold weather states and can't drive their cars year round.
http://www.ecklerscorvette.com/batte...side-post.html
When you turn off the car, pop the hood and turn the **** and your battery won't drain. also has a great secondary purpose as an anti-theft device. While it won't stop a determined thief it may slow them down a little or make them look for an easier target when the car won't crank.
Or maybe a "battery tender" like this one to keep your battery charged while it is the garage:
http://www.harborfreight.com/automat...ger-42292.html
Not much help if you have to park somewhere without an outlet though. Side advantage is, even a properly working C4 will still run down the battery if left sit long enough. The battery tender will keep the battery charged even if it sits for months like for all the poor schlobs that live in cold weather states and can't drive their cars year round.