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Great stuff as always DUB.
My dvm has milliamperes on it. Is that what I need to accurately detect a draw? Or is there a special tool that I need?
I looked back thru the posts, but I didn't see any confirmation that the battery has been tested. If it was, sorry I missed that info.
Voltage is nice to know, but conductance is also very important. Even using a simple carbon pile tester can give some idea of the batteries capability. Even a new battery can go bad and not actually hold it's charge.
I looked back thru the posts, but I didn't see any confirmation that the battery has been tested. If it was, sorry I missed that info.
Voltage is nice to know, but conductance is also very important. Even using a simple carbon pile tester can give some idea of the batteries capability. Even a new battery can go bad and not actually hold it's charge.
Cut and paste from post #1: I have a fairly new battery that I leave on a tender when the car sits
That's what I was going on to begin with. But testing it would be a good start, I agree.....
Agreed. I will take the battery out and have it tested today.
What I don't understand is ...
1. Why the car can sit for two hours and not start. AND
2. It can sit 24 hours and then start?
What can cause this contradiction?
SR,
Since you are going to take the battery out and have it tested you have to take the NEG ground off anyway. Do the drain test at that point after you pull the fuse for the alarm.
"" 1. Why the car can sit for two hours and not start. AND
2. It can sit 24 hours and then start?""
I think you have a drain and possibly an intermittent one but would like to see the test light results before anything crazy gets suggested.
EX: Have you ever had a switch that has to be wiggled a little work, one that has to be pushed/turned just the right way to work ? How about a "motor" that had to be tapped to work ? (Alternator, Blower motor, electrical fuel pump, power seat, power window etc ) Not saying that you have had to on your car but I'm just trying to make a simple, real world explanation that you'd understand so it answers your question Possible that something could be stuck on after a bump through either the component itself or a switch ?
I would say get the 30 second test done first since you are taking the battery out anyways and then come up with a plan of attck.
My $.02
SR, you're on the right track. Start at the Batt. and eliminate it as a source of trouble. I've been providing on-site, phone and email support for Electrical/Electronic equipment for 30+ years (Auto Mech. in the early 80's too, yuk) giving troubleshooting advice to end users and Techs and it's difficult at both ends. All of the suggestions I've read here are excellent but you'll be best off following a point by point method. Once you know the batt. is good (either load test or conductance) then I'd do the test light/meter check. A battery can have poor internal connections (plate straps or lug to plate) acting intermitently also (had a batt. blow up once while doing starter current draw test, had to use the chem. shower, acid everywhere). I'm predicting success soon.
Been along time since I been here....
Normally hang in the off topic sec where the action is....
Didn't read all the posts, but on our 81 the window switch would stick in the on position and man you could smell the plastic melting after awhile...
Didn't figure out what was draining the batt for some time till I noticed the switch.
And remember, It'll stick but look normal at rest position.
Take a look. hope that helps. Now back to the action...........
Great stuff as always DUB.
My dvm has milliamperes on it. Is that what I need to accurately detect a draw? Or is there a special tool that I need?
Yes, yes, yes!. That's how you measure parasitic drain!. 3 pages of this thread any nothing on measuring what the title says.
The basic method is to lift you're batt negative cable and use your meter to measure current by connecting between the batt cable clamp and the batt terminal. A heads up here is you normally have to move the meter lead terminal over to the terminal that's marked ma. Problem is you now open the door and turn on the courtesy lamps you will draw amps instead of ma. So start with the 10amp setting and terminal to see what you draw to begin with and if your meter is accurate enough to read ma on the Amps scale. I say this because it's very common to blow the ma fuse and the operator gets frustrated because he no longer can read any current at all.
Now that you are read to measure ma current you can pull select fuses to locate the high drain problems. Now how much is to much?? Well newer cars with all the new gadgets can be as high as 85ma - says Optima batt tech. But just yesterday my '94 Camaro w/PMC/EFI measured steady 5ma and only 2ma with the courtesy lamp fuse pulled. I guesstimate your 81 Vette is same or less.
I can't explain your 2 hour dead issue while 24 hours is better other than you left a door ajar or light on. BTW Hobo Fake has a decent little batt tester for 20 bucks.
SR, If your Batt. tests good I'd begin looking for poor connections (see DUB post) in either the Starter or Control Circuit (Solenoid etc.), although one of your earlier posts where you disconnected the Batt. for a long period and it cranked does suggest drain. I'll just read updates for a while as it looks like too many cooks at this point and I have a 68 which has different wiring. Just for my knowledge is your Batt. behind the Dr. seat like mine?
You guys are awesome. Thanks for the continued suggestions.
More Discoveries
I finally found the fuse that killed the audible part of the alarm. Although the test light continued to light in a pulsing fashion after I pulled that fuse. I shut the door and the courtesy lights were flashing in unison with the lit test light. I didn't go any farther as I was taking the battery out at that point.
The battery tested successfully when a load test was put on it at our local Interstate Batteries store. They said that the battery was in great shape.
Now with this new information I'm thinking I've got to find what's making the courtesy lights/test light pulse on and off. I guess it's back to pulling fuses again.
Am I correct?
Last edited by Street Rat; 12-02-2016 at 04:23 PM.
You guys are awesome. Thanks for the continued suggestions.
More Discoveries
I finally found the fuse that killed the audible part of the alarm. Although the test light continued to light in a pulsing fashion after I pulled that fuse. I shut the door and the courtesy lights were flashing in unison with the lit test light. I didn't go any farther as I was taking the battery out at that point.
The battery tested successfully when a load test was put on it at our local Interstate Batteries store. They said that the battery was in great shape.
Now with this new information I'm thinking I've got to find what's making the courtesy lights/test light pulse on and off. I guess it's back to pulling fuses again.
Am I correct?
Pull that alarm out, first, then go from there.....
I would have to say it has no significant power drain....because IF you had .300-.400 amps of power drain...it would eat you battery up over night.
Have you had a chance to locate and inspect that junction connector in your wiring harness that feeds wires to your starter???
I can not tell you on how many of these go bad...and if the car is driven and the engine compartment/engine is hot...this connection ( due to its location) can fail when it also get hot just by shear radiant heat. The if you include heat from wiring connectors that are not clean and tight...this compounds the problem.
You guys are awesome. Thanks for the continued suggestions.
More Discoveries
I finally found the fuse that killed the audible part of the alarm. Although the test light continued to light in a pulsing fashion after I pulled that fuse. I shut the door and the courtesy lights were flashing in unison with the lit test light. I didn't go any farther as I was taking the battery out at that point.
The battery tested successfully when a load test was put on it at our local Interstate Batteries store. They said that the battery was in great shape.
Now with this new information I'm thinking I've got to find what's making the courtesy lights/test light pulse on and off. I guess it's back to pulling fuses again.
Am I correct?
Today I put the battery back in the car and tested for current draws.
I slowly connected each wire that was previously connected to the battery positive. I checked for current draw on each wire. I found one wire hooked to the battery that was causing a drain. It was a wire a previous owner (BUBBA) connected to the battery for something. This wire was responsible for the courtesy lights flashing also. All other circuits had no draw. I was under the impression that this was a radio wire for a clock or such. It's yellow in color about 18 ga. I have not tracked the wire down yet. So right now that wire seems to be the culprit. We will see.
Today I put the battery back in the car and tested for current draws.
I slowly connected each wire that was previously connected to the battery positive. I checked for current draw on each wire. I found one wire hooked to the battery that was causing a drain. It was a wire a previous owner (BUBBA) connected to the battery for something. This wire was responsible for the courtesy lights flashing also. All other circuits had no draw. I was under the impression that this was a radio wire for a clock or such. It's yellow in color about 18 ga. I have not tracked the wire down yet. So right now that wire seems to be the culprit. We will see.
And what was the amp draw on this 'yellow' wire when you attached it???
How are these wires being attached to the 'battery positive' as you wrote? There should be no wires that you attach to the positive battery cable on your car. The positive wire attached to the battery is the cable. UNLESS they are using one of the special side terminal cable bolts that allows you to attach wires and not effect the battery cable making proper contact with the battery itself.
I know you know about this connector I previously mentioned...but I thought I would post photos of if so if other members not aware of what it looks like...they now have a reference.
I was using simply a test light to test for draws. The yellow wire made the courtesy lights go ape crap. They pulsated on and off until the timer kicked them off. The test light pulsated with the flashing of the courtesy lights.
12-01-2016, 09:50 PM
Possible that something could be stuck on after a bump through either the component itself or a switch ?
