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Hi All, I have a c3 1979 vette that I suspect has a battery drain somewhere. the battery gauge without the engine started points at 14-16. I read this is a sign suggesting the battery is being drained...
Now, after 15 days without starting the car is dead, won't start. it's because of the battery...
Does anyone know how to fix this? How I can search where is the drain? Do I need to disassemble the entire car?
Thank you
David
On most any car the quickest way to narrow it down is to unhooked the negative cable (safer) and run a test light in series (one end on the negative bat post/one end on the neg cable).....if there is a draw...the light will light up.....good....you confirmed the draw.....now start popping fuses out of the fuse box until the light goes out.....the fuse that makes it go out is the circuit with the draw....and you can start from there.....
This will not nail it....but it will get you in the game.
I have an aftermarket alarm system that will drain my battery in about 5 days. I purchased a small battery tender/charger and keep it hooked up when I'm not driving. No problems so far and I always have a hot battery.
Hi Jebbysan...I would like to test your approach but I don't understand the details. You mean placing the negative cable of the battery to a light bulb? while leaving the positive hooked to the battery? I didn't get your "test light in series"
thank you
d.
YES...the test light will let you know when you find the circuit that is at fault. BUT...it does not let you know the amount of amp draw.. If a person were to try to use the 'test light method' on a 1984-1996 Corvette...they would be shocked on how bright the test light shines and yet...the amp draw is IN the specified limits to keep the battery from going dead.
There often times a setting on a volt/ohmmeter that allows a person to use it to identify a amp draw.
DISCONNECT your negative battery cable....clip on the test light to the negative cable end...then the other end of the test light goes to the side post of your battery where the negative cable would attach.
There is NO REASON to pull every fuse.....Why??? Because the ONLY fuses you need to pull are those fuses that are working WITHOUT the ignition having to be turned ON. But pull them all if you feel the need. Because how can the wipers be pulling an amp load when it is not on??? Right???
HIGH CHANCES are the interior timer controller....which can still allow the interior light to go OFF..but will still draw current.
You wrote that your voltmeter reads 14-16 WITHOUT the engine running.....BUT you did not state if you had the IGNITION key turned to ON????
And when the engine is running...what does the voltmeter read????
Possible internal alternator issues can cause this drain also.
VISUALLY VERIFY that your battery cable terminals are CLEAN and that the cables are TIGHT!!! This does not effect a power drain...but it can effect how well the alternator is charging your battery.
Along with DUB's excellent suggestions… a simple check is to make sure your alternator belt is tight enough and the alternator is recharging your battery with sufficient voltage (approx. 14 volts output).
thank you for your kind advise. I attach pic of the battery gauge when the key in the ignition is turned ON...
Answering DUB: the reading in the picture happens with the ignition key turned ON
when the engine is running voltage stays at the same mark..
what is it the 'interior timer controller?"
There is NOTHING wrong with your charging system. WHEN the key is on...the volt gauge is showing what the battery has in it.....when the engine is running....it is showing what the system has. You are fine. IF----IF your gauge goes to 16...this is NOT GOOD!!! But where it is at is just fine.
Your interior timer controller is by your glove box....usually removing the glove box liner will allow you access it. It should be an orange box ...about half the size of a pack of cigarettes. BE careful with your glove box light socket.
Your interior timer controller is by your glove box....usually removing the glove box liner will allow you access it. It should be an orange box ...about half the size of a pack of cigarettes. BE careful with your glove box light socket.
Ok. Got it. Thank you so much. So if the battery gauge while driving goes to 17-18, is that bad?
thank you
d.
Yes, do not drive the car until you figure out the voltage issue, it is easy to check voltage with a multi-meter across the battery to see if it is a gauge or malfunctioning charging system.
You will burn the wiring if it is actually putting out 17-18.
My 79 also has a battery drain, I put a Moroso battery terminal shut off switch on the ground wire, $15 until I have time to find the source of the drain.
Oh, that was very helpful!
so if it goes to 17-18, does it mean it has a drain? then why it goes that high?
If ....when you are driving or the engine is running and go to 17-18...the voltage regulator in your alternator is NO LONGER REGULATING THE VOLTAGE.....THUS....the alternator can put into the electrical system whatever it chooses....because....it is NOT being regulated.
Originally Posted by siol
which is the ground wire you are describing? how the Moroso is installed? can you describe specifics?
Thank you so much
d.
The GROUND WIRE is your NEGATIVE BATTERY CABLE. many people install a 'throw lever' that allows them to lift the lever handle and ALL power is killed to the car.
Personally I do not like them because that is something that I have to worry about when working on a Corvette and going back to the battery and getting all of the loose 'stuff' tight so the charging system is working correctly. I prefer to FIX the problem and NOT have anything that can disturb the flow of current.
Do as you wish...I am NOT here to judge you. Just whatever you do ( install or modify)...do it right.
How old is your battery, have you been using a battery charger on it frequently. They can, I think ruin a battery if used frequently. Check your glove box lite too, occasionally the door does not contact the switch and the light stays on. As Dub stated a defective alternator will also drain a battery within days, or hours, good place to look first.
Ok, so how can I know if its the alternator? I mean, if it goes to 17 is that it? is the gauge at 17 the smoking gun that the alternator is NOT working?
I also prefer to try to fix the issue...but man, it seem it can be so many things...I have to go one step at a time...
Do as Dub said, and measure the voltage across the battery terminals with the engine running. If the actual voltage you measure is over 15v, you have a charging issue, like the regulator. If it is actually around 13 to 14v, you have a gauge problem. You should read the same thing (if all is well) across the battery that the gauge reads. So, with the key on (engine off) you should be reading around 12.4 volts across the battery and reading on the gauge. If the reading is ok, but the gauge reads higher, you'll know that the gauge needle is not showing you the correct voltage. You need a voltmeter. If you don't have one or can't borrow one, Harbor Freight sells one for under $10 that will do what you need.
In the picture you posted, if the engine isn't running, your gauge is not correct. A static battery should not read as high as your gauge. I guess it's theoretically possible that you alternator is overcharging and built the battery up that high, but I've never seen that. Measure to be sure. It's not related to a battery drain in my opinion, the high voltage is not an indication of a short or drain.
Last edited by 65GGvert; Jan 17, 2016 at 07:33 PM.
You wrote: IF.....BUT IS your volt gauge reading 17+ when the engine is running????
IF it is NOT you are worrying about nothing...in REGARDS to your alternator NOT being regulated.
AS for the pwoer drain.....you need to get the tool to find out how many amps are 'draining' as it is currently and take it from there.....SO.....to get back on track here...
You get the tool to see how many amps you are pulling when the engine is NOT running and the IGNITION key is NOT in the ignition.
THEN...if you show us how many amps you are pulling...then IF it is high enough to be a major concern.,..you go out and CAREFULLY unplug the two wire plug and remove the BIG red wire that is bolted to the backside of the alternator....BUT BE AWARE>....that the RED wire is HOT....meaning that IF it touches ANY STEEL..it can spark violently. AND TO STOP this from happening...you have to remove your NEGATIVE battery cable when doing so....and then re-install the negative cable when you get the red wire off the back of the alternator. DO NOT ALLOW the terminal of this big RED wire to spin/rotate...because it can potentially cause for an issue internally inside the alternator where components bolt up the the back side of this stud that you are taking the RED wire off of.
Until you know how many amps you are draining....it is all a guessing game.
Ok. I am getting multimeter...for sure there is something not ritght. I got one of those crappy multimeters and with the engine off, keys off, all off, the battery shows above 14V...I don't know exactly how much but is way off above the 12V...So Ill get back here when I got the proper digital multimeter...to be continued..
thank you for your ongoing support...
david.
Another easy check while you are ruling thingss out: the majority of my mystery battery drains have been interior lights and alarms. At night when your car is all charged up, go out to your garage with the lights out. Walk around and inspect through the windows with the doors closed and see if there's an interior light still left on... Maybe a faulty switch or the headlight switch was left turned to the "interior" setting by accident.
Last year I had this problem and my buddy noticed that my center console lid in the back was just ajar enough to leave its light on and I couldn't see it. It would actually drain the battery in a few days.
C3 79 battery drain
