johngammel

Went to drive my '88 yesterday and my 700 CCA Delco battery was totally dead - the doors, hatch and hood were closed. I had driven it the week before to/from a car show in Ft. Myers without any problems. I've also never had anything like that with this car in almost 20 years. Battery purchased new 11/2015. Charged it until this morning and charger indicated it was fully charged. Tested with my Schumacher resistance box and it was fine. Car started fine and voltage per gauge was 14.3. Before I start checking current drain and pulling fuses any quick thoughts?

65Z01

Not surprising that a 3+ yr old batt is done for.
However, have the batt tested.
Once a fresh batt is installed perform a leakage test to see if a parasite drain has developed.

hcbph

I had something in the console well that was pressing on the power seat switch continuously. Same scenario as you described.

Here's a picture of a meter I found at HF. You pull a fuse out of the fuse panel, plug it into the meter and plug the meter into the fuse panel where the fuse was located and it will show how much draw is going on that circuit. It can be very useful to figure out what's pulling that much juice. You can even check the relays in it if you make up some jumpers to adapt the relay to the meter.

Hope that helps.

johngammel

I did test the battery - it was OK. The car also started fine. There's likely a drain somewhere.

The last "electrical" work I did was to pull the speaker wires for the doors off and put shrink wrap on the contacts - I drove it back from a previous show in incredibly heavy rain and apparently enough water leaked in to zap the amplifiers. As soon as the show season is over I'll take the doors completely apart and send the amps to TX for rebuild.

I had this car in Minnesota for +10 years and here in Florida for +5 without anything like this. Strange...

pacoW

Until you get it fixed, this is a cheap way to prevent a dead battery. I use them on my C3 & C4.

https://www.walmart.com/ip/Vehicle-C...yABEgJp9_D_BwE

JBPC4

Are you 100% sure there wasn’t a door or something else not quite latched all the way? Mine went dead once sitting in the garage for a week with a door that just hadn’t latched and I didn’t notice it, so the interior lights drained the battery. If it holds a charge and doesn’t happen again I wouldn’t worry about it.

Hot Rod Roy

That's a great little device that makes a residual current drain test easy! With your hood up, hood lights disconnected, and doors closed, wait several minutes for all of you electronics to time out (go to sleep). Connect your amp meter/multimeter to read 100 mA scale between the battery terminal and the battery cable. Open that switch, and the amps shown on your meter is your residual current drain! It should be less than 50 mA. (My '84 is 13 mA).

That HF current tester isn't much good, because it can't test for anything less than 100 mA.

johngammel

With the hood up and the hood lights disconnected connect ammeter. Draws 3.47 for about a minute and then drops to .02 (two decimals is as fine as the scale goes).

I know the doors and hatch were closed. One of the hood lamps was replaced several years ago. Before I disconnected lamps checked that as I closed the hood the lights went out but of course I don't know if they stay extinguished. Think I'll hook them back up if no other suggestions and check them for a couple of nights when the garage is dark. I'll just have to fight with LED lights and motion sensors in my new sidewinder openers.

gpierce

I think what happens a lot that maybe people don't quite understand, is that with age components start to malfunction even when you don't touch them. This leads to the "all of a sudden my battery dies" thing like this. I would be doing drain checks, but since you did that a drain doesn't look like your problem to me. 20 milliamps is totally fine. Maybe just a dead battery and nothing else

Yukon Corleone

I am dealing with that now and was hoping it’s a bad battery but as someone said theses are older cars and things go wrong.

Edit:I should have quoted the post above mine

johngammel

This morning it was still drawing .02 so I removed the ammeter and drove to our very large Wednesday Morning Coffee (AKA old guys with old cars). Ran just fine and at off idle was 14.4 volts on the display. The start each time was normal so I guess there's not much else to do right now. Thanks for the ideas.

Special note - I did check the glove box light for proper operation and it was OK.

playsdixie

Who the heck knows!!...I check the draw/drain on the battery of my 85 all the time yet still every once in a while(once a month or so maybe) I go out there and she's dead....new battery......Now I have quick disconnects (to make checking battery drain easier) and keep the battery on a battery tender to avoid the problem.....

gerardvg

Hi
Check the antenna motor, listen out for a click noise every minute or so.
If the antenna does not open the contacts when fully retracted, the motor can activate not moving and trip the overload.
This can happen when the assembly jams, the antenna motor has power at all times.
Just listen out for a click near the antenna, has happened to me would drain a battery in a day or two.

johngammel

Interesting idea - I'll do that. How hot does the motor get? I'll assume eventually it will just burn out.

playsdixie

here are the pics

Paul Workman

Not a lot to add to the discussions regarding parasitic draw (aka "keep alive" for the computer (ECM, etc) and radio presets). However, if you're interested, here are some tidbits that may be useful to know.

• Typical charging voltage ranges from 14.7 when under hood temp are cold, and will taper off to 13.8 volts when under hood temps are warm AND the battery if fully charged.
• "Acceptable" parasitic draw is anything under 50mA for most cars, including Corvettes. That said, I have found that 25mA (.025A) ± 10mA is more typical for a C4 Corvette with stock radio (i.e., no after market stuff) etc. installed. Specifics for your Vette can be found in the FSM.
• A battery that is unloaded (except normal parasitic draws) that reads 12.2 volts in indicative of a fully discharged battery. Less than 12.2 (unloaded) is indicative of a severely discharged battery.
• And, except for normal parasitic draw, a battery that reads 10.1 to 10.5 volts may have experienced a shorted cell. (If after first attempting to charge a battery in such condition, after allowing it to sit for 30 minutes before measuring the voltage and it reads ~ 10 volts, the battery likely DOES have a shorted cell and is due for replacement.
• Lead and sulfuric acid react over time to form a layer of lead sulfate crystal formation that grows and creeps across the lead plate. This sulfate acts like an insulator covering the lead plates. As more and more of the plate's area is covered with the crystalline sulfate, the battery's capacity to provide electrical current is diminished. This phenomenon - a chemical reaction - is the "nature of the beast". But, this chemical reaction can be slowed by normal charging during the times the alternator is running. And, like "all" chemical reactions, they are slowed by decreasing the temperature. Sulfate formation is significantly retaded in a battery during winter (i.e., sub-freezing) temperatures.
• Many modern chargers have a de-sulfate mode which pulse charges the battery with a higher current than normal. The result is to break up and dissolve the crystal formation. (Chargers e.g., C-tek and Battery Tender, and others feature desulfate modes. Some chargers automatically revert to a pulse mode once the battery is fully charged.)
• AGM batteries were designed for the military to withstand violent shock experienced in armored vehicles (tanks, Humvees, etc.). They are constructed by rolling thin lead plates separated with a special paper that is soaked in sulfuric acid (electrolyte). There may be some very minor differences as far as charging and steady state voltage goes. But, they don't require exclusive AGM chargers: the same alternators in our Vettes or any other vehicles for that matter are perfectly capable of charging/maintaining AGM batteries. AND, the parameters are essentially the same for the common "flooded" lead-acid construction as it is for the AGM (rolled) batteries - far as charging voltages go and characteristics of depletion is concerned.

Anecdotal:
Now and again I've run across a battery that measured ZERO or perhaps only a volt or two, the result e.g., a courtesy light left burning overnight, or an antenna motor that for whatever reason was drawing a large parasitic current. Many sources, including the tech manuals for various chargers, indicate the battery is a lost cause and a replacement is required. (Harumph!!) NOT NECESSARILY I find!!

I happen to have a cheap, old battery charger, sans all the new fangled automatic electronic processors that will provide the necessary charging voltage/current to a battery (or a grapefruit, for that matter) and sometimes "resuscitate" a "dead" battery regardless of condition. (An older "trickle charger" will work as well I find) After a few hours of "resuscitation", such a battery has often recuperated enough for my "smart" automatic chargers to accept the hand off and finish the job. No question the capacity of the battery suffered for the experience, but reinstalled in the vehicle (Vette, lawnmower, etc.) continued to provide years of service.

In my experience, batteries in work vehicles (for example) that last about 5 years tops. Typically these vehicles were driven regularly during the work week, but NOT connected to an charger at any time the vehicles were idle. However, batteries (on my Vettes, motorcycles, lawnmower) that are attached to a (Battery Tender - i.e., "smart charger") have performed as new for periods well in excess of 10-12 years.

Hopefully, some will find a few nuggets that will help them next time the car won't start and before abusing their wallet for a new battery!

johngammel

I put my stethoscope on the antenna for 5 minutes and didn't hear anything. I also did some more test starts and drives with normal results. I think my next step is to see if I have a very sensitive door switch as was brought up at NCRS Lakeland last month. Just keep plugging until I exhaust all the possibilities and give up. Maybe I'll just have to get a new battery even though the old tests good.

Hot Rod Roy

I'd suggest you find the problem, rather than just throwing money down the toilet (unless you like collecting batteries).

johngammel

I tested both doors. At the midline they each need to open to about 2 1/2" before the interior light goes on. With boards stuck in each door so they are open 2" the light will extinguish when the timer expires. That's obviously open so I eliminating the door switches as a possible cause. ARGHHHH.

aklim

Did you do a load test on the battery where they actually put a resistance load on it? Next, repeat the test in 10 minutes. I have seen a battery that tested good and the power draw test after 10 minutes was lower by about 20%. Also check alternator.