Surfer69

Alternator and battery have been fine for over 5 years with no problems. Now car is showing signs of weak charge by slow start up and once now no start at all. When it didnt start meter on battery showed 12.3 volts maybe if I remember but when charging it's 14.5 which I think is OK and should mean alt is good. Just before normal start battery reads maybe 13.8 or something.

So I'm pretty sure I got some short or drain somewhere just dont know how to isolate and find it? Never been good with the electric stuff.

Any help is appreciated.

hugie82

5 years the batt might be on it's way out judging from your voltages. Most batt are 12.7 fully charged and the charging voltage should drop down after a day of use or a long trip. It should drop down to 13.0 to 13.5 after the ride but an easy test.....
place a multimeter on the battery and start pulling fuses one at a time. If you pull a fuse that makes the voltage go up by .01 or .02 volts you found the draw circuit.
What make battery do you have?

TedH

5 years out of a battery in a C3 is about the limit. Even with my tick-tock clock disconnected, I have to be careful to not let my C3 sit for more than a couple months without driving. My aftermarket JVC radio also does a better job of NOT draining the battery than the older dual-din SONY it replaced.

Replaced the battery last fall after about six years.

When I replaced my starter shortly after this battery change (unrelated, I ran it without shims and wore a bearing against the flexplate), I also replaced the ground wire connector from the harness that attaches approx 12ga wire at my bell housing bolt. Not sure if it is HEI-specific but it seemed to help hot starts on my car.

DUB

Surfer69,

If your engine cranks after sitting a few days...you do not have a significant drain to be concerned about.

Hugie82 is correct in his response.

100-200 milliamps of draw is normal. I prefer it to be NO MORE than that. And most of that will be your factory clock if still working.

I have to agree that it can be your battery...the condition of the cables to the battery...and the cables being TIGHT.

You can be having wear issues at the starter solenoid...or the connections at the solenoid are loose or dirty, etc.

What year is your Corvette????...because if it is a 1969...they did not have a voltmeter....they had an ammeter. So how is it you know the voltage value????

DUB

SH-60B

To answer your question, remove the battery ground cable and clip a test light from neg bat to neg cable. If it lights up you have a parastitc loss. Pull one fuse at a time to find the circuit that has the drain. The light goes out whan u find the draining circuit. For this to work the interior lights must be off, pull them out if nec., also if your radio has a memory pull it's fuse.

DUB

This test is not conclusive OR accurate.

YES...this test will let you know you have a power drain...but not letting you know how much. And that is what is important...is the amount of amp draw on the system. So you would have to know how your test light looks when it is 'glowing' and the value of amps that make it glow at that brightness. You can spend days trying to chase a 'demon' that is not there.....by NOT knowing the amount of AMPS the system is drawing. It is fine to have an amp draw.

For what it is worth.....if you owned a 1984-1996 Corvette and did this test with the test light.....you would be shocked on the fuses you would have to remove to make the test light bulb go off. And you would SWEAR that you have a problem ...when actually you do not...because once you used the tool that can read the amp draw...you would see that you are just fine.

I have had many people come by and tell me that they have an amp draw and can not tell me how many amps the system is drawing from it...but once I connect my tool to it...I un-hook it and walk away and tell them that they are fine...and do not worry about it. I tell them that they need to make sure all of the connections for the charging system are CLEAN and TIGHT and that the alternator is working and the battery is NOT old as the pyramids.

DUB

TX-Techman

I have a 69 as well and the best option is to get a multimeter with a milliamp setting. connect it in series with the negative battery terminal and see what the reading is with everything off. Mine is around 25 ma with everything off according to my Fluke 87. This is just from the clock and aftermarket radio draw, your should be similar unless you have something else going on.
If it is significantly more than that began removing fuses until the current draw is correct. By this process of elimination you can narrow down the culprit.
If all of that checks good and you have a standard battery, spend $2 and get a cheap hydrometer. A battery may put read plenty of voltage and still have a dead cell and I do not trust the electronic testers. Check each cell to see if they are all similar count of ***** floating. If all have none or few floating try charging the battery and retest. If most have 3 to 5 ***** floating and 1 or more have none or 1 floating you have a dead cell in the battery.
I also have an 08 and the battery kept going dead. Had it checked at the dealer, Autozone twice, and AAA once with all reporting the battery and charging system was fine. Battery would not hold for more than a couple of days if that so I finally picked up a new hydrometer and found 2 dead cells, replaced battery and no problems in 3 or 4 months.
Also if it is the battery I would recommend staying with a standard battery. I have had terrible luck with them in the 69.

Tim 1973

This is the best way IMO, do not forget to check the alternator, I have found them to be the culprit.

Surfer69

and we're back.....

Yeah the battery is Sears Die Hard standard cranking. I have a suspision this POS aftermarket radio KHE-300 is causing the problems since it has it's own issues. Clock is good and still runs so there should only be two draws. I was quoting volt numbers using cheap multimeter I have.

So I need to send radio back anyway for refund. I will do that and see if problem goes away. If not then looks like new battery is safe bet. Thanks all.

SH-60B

Uhhh, he has a '69, you're in the wrong forum section if you think he has a C4. And the test I described will do exactly what I said it would, find the circuit with the drain on it. It won't find the amount of the drain, but that's really a secondary issue as there should be absolutely no drain on the battery of a '69, memory radio and all lights off as I described.

Thanks though for reminding me why I don't post much on this forum any more, too much BS for the height of my boots. Have a nice day, uhhh..."DUB"

DUB

NO B.S here...I was just STATING FACTS!!!

I do not know or care if you know..BUT I do this everyday...and even though your information was useful...it was NOT conclusive. And I can not sit silent when I know I can add information from EXPERIENCE that can help forum members.....even if you take it like a direct attack on you...which is was not!

Finding the circuit is ONE THING...KNOWING how much is being drained is another ...AND you initial post stated NOTHING to that FACT...so I was just adding the information so the guy would not be wondering what is going on.

I am QUITE AWARE that he has a 69. I was using the C4 as a reference to amp draw values..so to speak. Because if a person were to use the test light only....it could cause them much grief because..AS I WROTE ...the test light does not give a value. Unless you want people pulling fuses on a system that does not have a high enough amp draw value to drain a battery. SERIOUSLY!

There is a drain on the system in a 1969...unless you feel that the clock is getting power from some other source other than the battery. There is a drain...slight as it may be....still a drain. About 100 milliamps.

You have a GREAT DAY

DUB

mikey

if you want to find the drain very quickly, just look under the car for a puddle of electrons. they'll be right below whatever is draining, unless of course your garage floor isn't flat or you're parked on an incline.

obas

Surfer69

Update:

So pulled radio and that wasnt it so bought new battery and it appears that's what it was since it's been two days now and the car starts fine everytime.

There is still a chance if I had a drain it hasnt affected the new battery yet but hopefully all is good. THX

joewill

some cars with aftermarket radio will have about a 10 milli-amp draw to keep its presets active, and your phone charger may draw a little also, your clock will draw a little also.. you should not have an amp.. (or I call it 1 amp) that is too much and will drain a good battery in a few days.. also a bad diode in your alternator could be the problem. all of these are hot circuits with the car and key off. a 15 milli-amp draw will drain the battery in about 2 months or more depending on your battery size and condition and age.

you still may have a draw but the new battery will not deplete as fast and will only seemingly solve your problem. wait a week between starts and see what happens.

Surfer69

Joe that's what I'm still worried about exactly. Can the multimeter read amp draws straight from battery or do you have to take off one of the leads or something?

GCM

My 84 Vette, starting with a fully charged battery and new alternator, will only show a maximum of 13.4 volts on the dash voltmeter which steadily drops throughout the day as I am driving it until it gets down around 12.4 volts whereupon it dies and will not restart. I have been through 2 new batteries and 2 new alternators with no change so I know that the problem does not exist with this part of the charging circuit. Someone suggested that this could be a problem with the charging wire off of my alternator and possibly a fusible link or the excitation wire to the alternator. Can anyone tell me how to find the actual problem?
Thanx
GCM

DUB

I know you do not want to read this...BUT...

You have a battery that starts off when the engine is running is at 13.4 volts....then it begins to drop and finally dies at or around the 12.4 volts.

I would be really looking at the condition of your battery cable ends on the cables....and making sure the terminal bolts are tight.

I would NOT ASSUME that the large red wire that bolts onto the back side of the alternator is actually good. I have encountered many where the strands of the wire were broken INSIDE the insulation and was not allowing the circuit to charge correctly.

Have you removed the alternators and had them tested AFTER the engine died???? I know that the company that rebuilt my alternators always told me to be very careful when I an tightening and LOOSENING the nut where this large red wire is secured to the backside of the alternator. 'They' told me if the stud spins...it can effect the internals of the alternator.

I am suspect that it is the alternator. Check your grounds...making sure they are clean. I would also look at and inspect the positive battery cable at your starter solenoid.

Also...you do not have any of these pulleys that reduce there diameters. Back in the day I had many customers who had me put them on...only to have me put it back to factory due to the alternator did not want to charge at idle.

DUB

TX-Techman

You cannot rely on the volt meter on the dash and voltage is not a good indication of battery and charging system condition.
On that model of vehicle I would crank it up and with it running pull the cable off the battery. If it dies you have a charging issue for sure, but if it keeps running the charging system is putting out something anyway.

DO NOT USE THIS TEST ON NEWER VEHiCLES, it may blow the alternator.

You may still have a charging issue but it is at least putting out. With the system discharging this rapidly I suspect a severe overload situation when comparing charging system output to actual load. It would be great if you had access to a good clip on DC amp meter, but I suspect that is not the case and they are pretty expensive. With that you would be able to see what is really going on. The alternator will only put out what is needed up to it's maximum. If you have the correct alternator and the pulley size has not be changed it should not be working hard at all if all the lights and everything is off except for neccessary things like ignition, fuel pump, ...

It definitely sounds like you are taking more out than is being produced. If all looks good but the problem persist you must track down the power consuming components and modify to bring into compliance. A volt meter is helpul but is not the best tool for narrowing the issue down.

Questions;
1. What capacity is your alternator. Looks like it should be 140amp output. If you had a 90 or 100 amp unit that could be a problem.
2. Do you have any aftermarket electronics? lighting, audio amps...
3. Have you converted any other components that were mechanical
but are now electric? This includes cooling fans, lighting, pumps...

DUB

140 Amp output is really high and WAY above what came in the car originally.

1984 early alternators were 97 amp alternators....then late 1984 and 1985 went to 120 amp...then went back down to 105 amp in 1986.

He already has electric fans from the factory....a primary fan and if it has the auxiliary fan...that will make it two electric fans.

I seriously doubt that there is a component that is 'eating' up the power that the alternator is producing. The PROBLEM is in the charging system...as I wrote in my past post. Wiring, alternator, cable ends, over sized pulleys....something.

DUB