TAC

I would like to test my car to see if it's pulling more juice while just sitting there than it's supposed to. I have a multi-meter but never got around to learning how to use it. Is there a relatively easy instruction set on how to test my car's sitting electrical drain? TIA

LarryW

I came across this thread on the "other forum"; it provides an excellent illustration on how to hook up a meter to check for battery drain:

Battery Dies after 1.5 weeks in storage (see the 4th post down).

Per this diagram, the draw should not exceed 100 mA.

Larry

ZeeOSix

The parasitic battery current should be about 20 mA on the C5 Vette.

Do a search on the other site for "parasitic current" and you'll find some super detailed posts about how I tested mine. You have to wait about 20 minutes to let all the computers "go to sleep" before the parasitic drain goes down to 20 mA.

TAC

Great Instructions! I need some help with the results. With the hood light left in place when I hook up the meter the light comes on and I read 2.28A right away. After about 10 seconds the amperage drops to .345 A for a brief moment or two and then drops to .08 A. From there it holds steady. If I remove the hood light and then hook up the meter I read 1.24 A right away. After about 10 seconds the amperage again drops to .345 A for a brief moment or two and then drops to .08 A. Am I right in thinking all is well? Does .08 A equate to 80 mA? I can't ever try it with the meter set to 400mA because it draws too much to start with.

Thanks much for all the help. This forum is !

TAC

I take it you had different type of meter leads? Mine are probe type. Do you tape them in place or something?

TAC

I added my test results to your post on Z06vette.com. I'll add them here as well. Looks like my car is right on target with a final drain of .01-.02 A loss. Thats 10-20 mA, right?

XXXXXXXXXXXX

I did my own tests and here's my results. All stock '03 Z06

Everything functional - the hood was left up the entire time.

Time 0:00 Hood up and Doors Open - 6.8A

As soon as door closed - 5.40 A

+ 45 sec - 2.8 A hood light still on

+ 50 sec - 1.8 A hood light still on

+ 60 Sec - 1.1 A hood light still on

+ 10.5 Min - .08 A hood light goes off

+ 13 Min - 0.01/.02 A Everything apparently off

ZeeOSix

Looks normal to me.

TAC

I charged the Optima most the day yesterday on the bench. It read 13.42V at 10pm and by 5am today it was at 11.73V. I guess that shows the battery is bad.

ZeeOSix

Yes, it's bad. I went through that fiasco too. Do a search on the other site for Optima battery and you'll find many threads of my Optima battery testing results. Also there is info on how to read the date code that’s burned into the batteries.

I had two Optimas that were bad and got both replaced under warranty. At lest Optima has a decent warranty on them.

zalama

Great discussion here!
So, I have -99 C5.
I have second optima battery now in 9 months, first yellow lasted 2 months.
Now after sitting the car about 1 week my present red optima is all dead.
I checked my battery drainage too:
After the alarm goes on its's 4 amp for few seconds, drops down to 0.8 amps. My only concern is why it only drops down to 0.2 amp(200 mA). I have removed all the fuses and it's still 0.2 A.

This will drain my model 75/25 red optima battery as calculeted :
44 A/0.2 Ah= 220hours=9.1 days.
(Anyway I think the cranking ability is reduced a lot before all the charge is gone)

PS.
I just realized how low AMP/hours this optima battery has.
I'm used to see 60A/h on most cars.

Anyway I think I need to get third battery?!

ZeeOSix

I'd have to dig my notes out, but if I remember correctly the battery current draw wasn't as high as 200 mA when the stock alarm was on. You say 0.8 amp and then 0.2 amps. Kind of confused ... which one is it?

Maybe you have an after market alarm?

Update -- found my thread on the other site. Look at post #4, Item C):
http://www.z06vette.com/forums/showthread.php?t=69875

"C) I set the alarm and after about 10 minutes the current draw on the battery went all the way down to the same 18 mA (key out of ignition) level. Apparently, once the alarm is set the computer must go to sleep, but has the ability to sense if there is any current draw on the system, which would then wake it up and set off the alarm. So, arming the alarm in the garage will not cause more drain on the battery ... something I wouldn't have expected, but good to know."

erick_e

My redtop will drop to 11.7 a few hours after sitting, and down to 10.1 after a day or two. The car reads 14.1 while charging.

After reading this thread, I finally decided to check for parasitic loss.

I came up with 1.5A immediately, and stayed there. I decided to double check it again and then it measured 1.5A and after a few seconds it dropped to .8A then a few seconds later it dropped to .01A

What relay is it that I hear when I connect the multimeter leads? It is located in the right front somewhere. Is it possible that this relay is sticking and allowing a circuit to stay closed, or is my redtop about to die?

ZeeOSix

If you read this thread carefully, you will see that it takes 15 to 20 minutes for all the computers to "go to sleep" before the battery draw drops to the normal 20 mA or less. Read my link a few posts above.

If after say 30 minutes the current draw is still much higher than this, then there is definitely a problem.

Optima Redtops are notorious for going bad ... so if the parasitic current draw is normal it has to be the battery.

zalama

Sorry about confusing info. So when alarm goes on, amps jump very quickly to over 10 amps(Can't really see exact value with digital meter) and then drops to about 0.8, then after few seconds, drop to 0.2 amps.
I waited few minutes and it stays at 0.2 Amps. I guess I need to wait little longer.

I allso hear "click" somewhere from head light motor everytime battery is connected, and amps flash to 4.0 and go soon back 0.2 amps.
This sound is not the light motor because I removed light connectors and still hear that click.
There must be something under the headlight. (horn?)

ZeeOSix

Yes, wait about 20 minutes and see if the current draw goes down to about 20 mA (0.020 amps).

QKSLVRZ

TAC,
There's an easy way to measure your current on the 400 ma scale.

So once you're disconnected the battery, and have the meter hooked up, turn the car on, wait until the current drops, then short the 2 leads on the meter out (so power doesn't go off), with the meter shorted, switch to 400 ma, then unshort the meter, it's on 400 ma scale, and the power never got disconnected so the alarm doesn't cycle.

BTW, my car ran right about 18ma.

Oh, down't forget your radar detectors don't shut off.

And remember current meters go in series, and you can short them, Volt meters go across the voltage, and shorting the leads would be a bad thing.

TAC

Being an electrical neophyte I have no idea how to short the meter. I wondered how people got their meter on the 400a setting without blowing the 2A fuse on that setting. In order to do my experiement I actually taped a wire to the negative cable and taped the other end to my probe. I then clamped the other lead to the negative post (Optima-has both side and top connections).

I was going to try simply attaching the negative cable back to the battery with my meter probes intact, retaining power in it's current condition (no pun intended). Then I could move the lead to the 400mA port and switch the meter to the 400mA setting and then remove the negative cable back out of the battery. I chickened out, figuring I would blow up something.