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Sure sounds that way. Get one of these (picked it up at HF) and check the various circuits in the fuse panel and see which is drawing high.
Another thing you can do is charge the battery, unhook the battery cable for a few days then hook it up and see if it starts or not. Still could be battery related.
Some places you might want to begin checking- lighting circuits- especially things like glove box where a light may be stuck ON but you might not see it so easily. Also, if your car has
the climate control option, the resistor module might have gone bad and continually draws current. Good luck.
Sure sounds that way. Get one of these (picked it up at HF) and check the various circuits in the fuse panel and see which is drawing high.
Another thing you can do is charge the battery, unhook the battery cable for a few days then hook it up and see if it starts or not. Still could be battery related.
You also can take a peek in the dark to see if anything is lit up....also....jump a meter across the positive terminal and the positive post....with everything off.....if amp draw, pull fuses until it drops....that's the offending circuit...i'd be looking at the courtesy circuit......
I've noticed with my 86 that the battery will lose about 40% of the charge if it sits for a week. Mine is bone stock. Haven't gotten around to troubleshooting yet, just put a longer cord on my battery tender so I keep it topped off.
I saw this on a repair video (not corvette but relevent). After you charge and let it sit for awhile, touch the alternator and see if it's warmer than it ought to be. Video I saw had a drain through the alternator.
SLVRSHRK, You really should get that looked at or fixed as that much of a power loss would make a lot of potential heat someplace. I hope that your battery is just old and shot and that your car is fine!
I have a battery disconnect I use on my 1988 C4, I have a jumper around it for the clock but have small fuse in it. Do you drive the car very often? There are plenty of people that start their parked cars and let them run for 10 minutes each month just to exercise the various parts. When you drive the car the vibration and road conditions as well as the charging system help de-stratify the batteries electrolyte. An occasional drive is probably better for the battery than just plugging it in.
Batteries are strange creatures, there are no two alike and despite this we still try to charge them all the same way. I take my battery out of the car when I am not using it for any period. This is a good thing to do as batteries too need maintenance. It is a good thing to take it out and charge it at a high enough rate that it will start bubbling the electrolyte. Most small chargers can't do this very well and the result is Acid Stratification and when this happens you are really only using as small percentage of the batteries capacity. The batteries I am describing are not anything fancy, I still prefer Flooded Lead Acid batteries in my "day-to-day" usage cars. I see people selling all kinds today, last week I was approached about a Lithium Iron Phosphate battery for car applications. Currently you can get several types of battery for your car and each prefers to be charged in it's own fashion. Have you ever seen any variable charging options for the newer batteries? Car manufacturers are going to have to either tell you what kind of battery type to use or have variable charging algorithms to accommodate the different types of batteries. There is no one alternator that can charge the newer technology battery types very effectively.
I am retired from the Photo-voltaic Solar Industry where we used batteries for storing the power we made. I would test each battery type and develop our own unique way of charging that type of battery.
So, back to your car, lets say you have 100 amps stored in that battery, you are telling us that you loose 40 amps in one week?
You should go to harbor freight and get one of those circuit testers (I have two of each size). They are very valuable in solving issues like yours. Before you start, charge that battery all the way up, out of the car and then get it tested. If a battery develops an internal short it gets ugly real fast, you have Hydrogen, oxygen and lots of heat. They can make a huge bang if they go fast! Have you ever seen or heard one blow up? I have and it makes a real mess as electrolyte goes everywhere and burns your paint, skin or anything it comes in contact with.
If I had a loss like what you are describing then the first thing you need to do is test that battery. I use large power resistors to discharge batteries, In your batteries situation I would charge it, drain it, and charge it again before testing it. Before you go too far open the battery up and check the electrolyte level, if low add distilled water and charge it. A lot of "Maintenance Free" batteries are standard FLA batteries and have a way into the cells to add water.
Give your present battery a fighting chance before spending another $150-200 for a decent battery. Batteries are getting more expensive because of the lead recycling that needs to be done when you are finished with the battery. I use Inter-State Batteries as I have had good experience with them in automobile applications.
Clear your battery of any wrong-doings first, then find that drain in your car. You can measure the current "leaving" the battery with either a DC current shunt or a DC ammeter or even the harbor freight gadget will suffice. I wish you the very best and I really hope that you are not literally loosing that much power. Most of all I wish you the very best in solving this issue with your Corvette.
If and when you test your alternator, check with a good multimeter that there is no AC coming out of the alternator, AC ripple coming from an alternator can really make a mess out of your car's Computer systems. Frequently people just measure the Direct Current and assume there is no AC voltage present. Alternator's have been known to damage the diodes that they use to make the AC in to DC and the result is you end up charging your battery with Alternating current and that doesn't work very well.
1986 - Battery goes dead after 3 days of not starting, battery is a year old, something is draining it?
Hi
Check the antenna motor, the tension when the antenna is fully down will open a contact.
If not the overload will click every minute or so, that can flatten a good battery in a day or two.
Had that happen to my 85, needed to disassemble the motor assembly and grease it.
A battery can be damaged and never be the same, that's why I use a deep cycle optima battery.
It will bounce back from being completely discharged, the plates do not buckle under high current drains like standard batteries.
My optima is seven years old and going strong on my C4 that is used on weekends only, it will cope with a month of not being used and start right up.
The advice given above is good - but IMHO - before you begin to pull each fuse and check for current draw - you need to figure out if you have a current draw problem.
Disconnect one battery lead (I suggest neg - but pos will also work) then get a meter that measures DC Current, and connect it from the Battery post to the disconnected cable. Set the meter to the 10 Amp scale, and since you have EFI - let things just sit for 5 min or so - then look at the meter - it should be reading something in the dozens of milliamps range (which may well read as zero on the 10 Amp range). If the current draw is in the tenths of an amp - to 1+ Amp - you have just verified that you have a problem.
Once you have determined you have a problem - then it's time to go fuse by fuse to try to pinpoint where the issue may be. But remember - there are things like the alternator, the starter and a few others that are hooked up to the battery pos terminal directly - no fuse. So ... if you pull each fuse and find nothing - then you get to disconnect the alternator, the starter, etc. etc. etc.
The reason I say to wait 5 minutes is that each time you power some of the computers up - they take a period of time to go back to sleep - so they may continue to draw "operating current" for several minutes after they wake up.
SLVRSHRK, You really should get that looked at or fixed as that much of a power loss would make a lot of potential heat someplace. I hope that your battery is just old and shot and that your car is fine!
I have a battery disconnect I use on my 1988 C4, I have a jumper around it for the clock but have small fuse in it. Do you drive the car very often? There are plenty of people that start their parked cars and let them run for 10 minutes each month just to exercise the various parts. When you drive the car the vibration and road conditions as well as the charging system help de-stratify the batteries electrolyte. An occasional drive is probably better for the battery than just plugging it in.
Batteries are strange creatures, there are no two alike and despite this we still try to charge them all the same way. I take my battery out of the car when I am not using it for any period. This is a good thing to do as batteries too need maintenance. It is a good thing to take it out and charge it at a high enough rate that it will start bubbling the electrolyte. Most small chargers can't do this very well and the result is Acid Stratification and when this happens you are really only using as small percentage of the batteries capacity. The batteries I am describing are not anything fancy, I still prefer Flooded Lead Acid batteries in my "day-to-day" usage cars. I see people selling all kinds today, last week I was approached about a Lithium Iron Phosphate battery for car applications. Currently you can get several types of battery for your car and each prefers to be charged in it's own fashion. Have you ever seen any variable charging options for the newer batteries? Car manufacturers are going to have to either tell you what kind of battery type to use or have variable charging algorithms to accommodate the different types of batteries. There is no one alternator that can charge the newer technology battery types very effectively.
I am retired from the Photo-voltaic Solar Industry where we used batteries for storing the power we made. I would test each battery type and develop our own unique way of charging that type of battery.
So, back to your car, lets say you have 100 amps stored in that battery, you are telling us that you loose 40 amps in one week?
You should go to harbor freight and get one of those circuit testers (I have two of each size). They are very valuable in solving issues like yours. Before you start, charge that battery all the way up, out of the car and then get it tested. If a battery develops an internal short it gets ugly real fast, you have Hydrogen, oxygen and lots of heat. They can make a huge bang if they go fast! Have you ever seen or heard one blow up? I have and it makes a real mess as electrolyte goes everywhere and burns your paint, skin or anything it comes in contact with.
If I had a loss like what you are describing then the first thing you need to do is test that battery. I use large power resistors to discharge batteries, In your batteries situation I would charge it, drain it, and charge it again before testing it. Before you go too far open the battery up and check the electrolyte level, if low add distilled water and charge it. A lot of "Maintenance Free" batteries are standard FLA batteries and have a way into the cells to add water.
Give your present battery a fighting chance before spending another $150-200 for a decent battery. Batteries are getting more expensive because of the lead recycling that needs to be done when you are finished with the battery. I use Inter-State Batteries as I have had good experience with them in automobile applications.
Clear your battery of any wrong-doings first, then find that drain in your car. You can measure the current "leaving" the battery with either a DC current shunt or a DC ammeter or even the harbor freight gadget will suffice. I wish you the very best and I really hope that you are not literally loosing that much power. Most of all I wish you the very best in solving this issue with your Corvette.
If and when you test your alternator, check with a good multimeter that there is no AC coming out of the alternator, AC ripple coming from an alternator can really make a mess out of your car's Computer systems. Frequently people just measure the Direct Current and assume there is no AC voltage present. Alternator's have been known to damage the diodes that they use to make the AC in to DC and the result is you end up charging your battery with Alternating current and that doesn't work very well.
Keep that Corvette on the Road where it belongs!
I always appreciate well thought out good advice, so thank you. In terms of driving the car, I tend to drive it almost weekly for a short run at least. I don't like to have them sit, mainly because I like to move the valvetrain in the engine so the same springs don't get compressed for long periods.
In terms of the battery, the battery that came with the car never could hold a charge for a long period of time, and it finally went to zero volts while I was on vacation a few weeks ago and was unrecoverable. I replaced it with a brand new Autocraft Gold (and yes, you are right about battery prices ). I the 40% was an estimate from memory and was with the old battery, but I agree the draw seems higher than it should be and needs to be explored. I'm going to throw a multimeter on it tonight and measure the resting amperage draw, and then leave it disconnected as I am headed out for a few days.
The advice given above is good - but IMHO - before you begin to pull each fuse and check for current draw - you need to figure out if you have a current draw problem.
Disconnect one battery lead (I suggest neg - but pos will also work) then get a meter that measures DC Current, and connect it from the Battery post to the disconnected cable. Set the meter to the 10 Amp scale, and since you have EFI - let things just sit for 5 min or so - then look at the meter - it should be reading something in the dozens of milliamps range (which may well read as zero on the 10 Amp range). If the current draw is in the tenths of an amp - to 1+ Amp - you have just verified that you have a problem.
Once you have determined you have a problem - then it's time to go fuse by fuse to try to pinpoint where the issue may be. But remember - there are things like the alternator, the starter and a few others that are hooked up to the battery pos terminal directly - no fuse. So ... if you pull each fuse and find nothing - then you get to disconnect the alternator, the starter, etc. etc. etc.
The reason I say to wait 5 minutes is that each time you power some of the computers up - they take a period of time to go back to sleep - so they may continue to draw "operating current" for several minutes after they wake up.
GOOD LUCK !!!
Good point on the 5 minutes......I chased my tail for a few days not realizing that every time I put the meter in series with the cable and post, I woke up crap.....looked all over for a drain I didn't have..
Sounds crazy but when we ran a DVOM from one terminal to a midpoint in the plastic case, we actually got a voltage. Granted that the battery was dirty and that it could have somehow become a conductor, it did surprise us when we did it. It was a while ago so can't remember the details.
Sounds crazy but when we ran a DVOM from one terminal to a midpoint in the plastic case, we actually got a voltage. Granted that the battery was dirty and that it could have somehow become a conductor, it did surprise us when we did it. It was a while ago so can't remember the details.
Truthfully - doesn't sound crazy to me at all !!! You had some slightly conductive crud on the top of the battery, and with the ultra high input impedance of the digital meter - the crud was able to pass enough current for the meter to read a small voltage ... I'd be willing to bet an analog meter (with its lower input impedance) would read a significantly lower voltage - if it showed any voltage at all.
This is the exact reason that some techs use a test light to do electrical troubleshooting on things like car stereo installs. A meter may read 12V when there is a marginal connection - simply because only 0.00002 amps are flowing - whereas a test light uses maybe 1/2 an amp - which is enough of a load to find things like bad grounds etc. etc. etc.
My 86 coupe had a big drain!!! I forgot the meter readings but; they were crazy high!!! My problem ending up being a fusible link behind the battery. Instead of fixing it, someone ran a hot wire to the windshield wiper motor. The car is never in the rain, so I never looked or had a problem. If I put the wipers on, the service light would come on and the car would almost stall. The hot wire was running to relay behind the battery.
unhook the negative side of the battery. Take a test light, put one end against the negative battery cable and the other end against the negative side of the battery. If the test light lights up then you have a battery drain the test light will light up. If it is light up the start pulling fuses until the light dims or goes out. If the light dims or goes out then there is a drain in the circuit that fuse protects. If the light doesn't change then the drain is from something that ins't a fused circuit. In the event the test light doesn't light up then there is no drain and it is the battery. Try that then report back.
I always appreciate well thought out good advice, so thank you. In terms of driving the car, I tend to drive it almost weekly for a short run at least. I don't like to have them sit, mainly because I like to move the valvetrain in the engine so the same springs don't get compressed for long periods.
In terms of the battery, the battery that came with the car never could hold a charge for a long period of time, and it finally went to zero volts while I was on vacation a few weeks ago and was unrecoverable. I replaced it with a brand new Autocraft Gold (and yes, you are right about battery prices ). I the 40% was an estimate from memory and was with the old battery, but I agree the draw seems higher than it should be and needs to be explored. I'm going to throw a multimeter on it tonight and measure the resting amperage draw, and then leave it disconnected as I am headed out for a few days.
Stay well
I checked the draw with the car at rest after the interior lights timed out and it was on the order of 9-10 milli amps. After a week of sitting, the battery is still registering 12.6 volts. I believe my issue was probably a faulty battery which would not consistently hold a charge.
I checked the draw with the car at rest after the interior lights timed out and it was on the order of 9-10 milli amps. After a week of sitting, the battery is still registering 12.6 volts. I believe my issue was probably a faulty battery which would not consistently hold a charge.
9 - 10 mA is more than just fine.... Nothing wrong there !!!
Now go have some fun driving her.
I've got a similar problem with my 86. It's the courtesy light circuit that drains the battery. The interior lights stay on all the time so I pulled the fuse. I need to figure out what is the cause. Now that I know it's the courtesy light circuit, how do I troubleshoot to find the reason?
08-06-2018, 08:53 AM
You also can take a peek in the dark to see if anything is lit up....also....jump a meter across the positive terminal and the positive post....with everything off.....if amp draw, pull fuses until it drops....that's the offending circuit...i'd be looking at the courtesy circuit......
). I the 40% was an estimate from memory and was with the old battery, but I agree the draw seems higher than it should be and needs to be explored. I'm going to throw a multimeter on it tonight and measure the resting amperage draw, and then leave it disconnected as I am headed out for a few days.
