Battery Drain- Did I do this right
Thread Starter
Racer
Joined: Oct 2005
Posts: 457
Likes: 1
From: Royal Oak Michigan
Battery Drain- Did I do this right
1980 L48 Auto
I have been rootcausing a alternator/starter/battery issue for a few weeks now and I checked for battery draw yesterday based on posts in this forum.
Please confirm my process and results:
1. disconnected + battery cable at the battery (red wire)
2. set my ohmmeter to "DCA" 20mA
3. Set it in series between the battery and + cable
4. closed the doors
My results were 0.00 mA. draw
I checked for voltage with it in series and was getting about 12V.
Is this possbile (clock does not work) or is this an indication of some problem in the system?
When I did this a couple of years ago I was getting 8-9 mA draw (my clock worked then).
My issue with the alternator is that the volt gauge in the car jumps all around and I confirmed that at the battery and at the alternator- I am replacing it today.
All my connections at the starter look good and solid- no corrosion on any of the terminals.
Any comments would be appreciated
Darrel1
I have been rootcausing a alternator/starter/battery issue for a few weeks now and I checked for battery draw yesterday based on posts in this forum.
Please confirm my process and results:
1. disconnected + battery cable at the battery (red wire)
2. set my ohmmeter to "DCA" 20mA
3. Set it in series between the battery and + cable
4. closed the doors
My results were 0.00 mA. draw
I checked for voltage with it in series and was getting about 12V.
Is this possbile (clock does not work) or is this an indication of some problem in the system?
When I did this a couple of years ago I was getting 8-9 mA draw (my clock worked then).
My issue with the alternator is that the volt gauge in the car jumps all around and I confirmed that at the battery and at the alternator- I am replacing it today.
All my connections at the starter look good and solid- no corrosion on any of the terminals.
Any comments would be appreciated
Darrel1
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Yes, you did the analysis correctly. Since you show no current draw, that indicates that nothing is ON when it's not suppose to be. A fully charged battery should be close to 13 volts with no load. Yours is kind of low. Sounds like a battery or charging problem.
Gary
Gary
Thread Starter
Racer
Joined: Oct 2005
Posts: 457
Likes: 1
From: Royal Oak Michigan
My dome lights are not working at this time have not rootcaused that yet- the bulb is out
How do I tell if I popped my fuse in the meter- it still measures voltage is the Amp setting a different fuse??
Darrel1
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
take the cover off your meter and just check the fuse for continuity.. if you connected it with your doors open you would have drawn 1000MA on the 20MA setting.. always start on the highest amp setting and work your way down.
make sure you have a good reliable reading on your MA draw..
i don't know if you should have other small current draws with an 80..
maybe radio presets, or any other aftermarket equipment?
if your battery is more than 3 years old, you can do no wrong by just replaceing it with the biggest amp cca battery you can find..
make sure you have a good reliable reading on your MA draw..
i don't know if you should have other small current draws with an 80..
maybe radio presets, or any other aftermarket equipment?
if your battery is more than 3 years old, you can do no wrong by just replaceing it with the biggest amp cca battery you can find..
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
20 Ma is to low a setting. Roger is correct, you either poped a fuse or fried the meter. Always use the highest setting when your measuring something unknown. All of my meters have a 2000ma (2 amps) setting, thats the place to start, then turn it down to a more appropriate setting if needed. The fact that you measured 12v (approx) with the meter on volts and connected between the battery termional and the red cable means you have a path and should have read some amount of current. Some meters have a 10amp setting, use that first if you have it to make the first test.
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
20 Ma is to low a setting. Roger is correct, you either poped a fuse or fried the meter. Always use the highest setting when your measuring something unknown. All of my meters have a 2000ma (2 amps) setting, thats the place to start, then turn it down to a more appropriate setting if needed. The fact that you measured 12v (approx) with the meter on volts and connected between the battery termional and the red cable means you have a path and should have read some amount of current. Some meters have a 10amp setting, use that first if you have it to make the first test.
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
My '78 measures 3.5 mA with no clock, stereo or alarm (fuses out). A friend advidsed me to use an analogue meter for chasing small draws. What draws the 3.5 is a mystery to me but it doesn't run down the battery.
Heel & Toe
Joined: May 2009
Posts: 15
Likes: 0
It sounds like to me that you have a bad ground. Check your negative battery cable. I just bought a 1975 vette and the guy told me that he had to replace the battery once a year and thought it was the clock draining the battery. When I bought it, the car turned over real slow before it started. I then started replacing fuel lines and noticed that the negative cable was broke where it bolts to the frame and he had a clamp holding the cable to the frame. I replaced the negative cable and the car turns over great.
Thread Starter
Racer
Joined: Oct 2005
Posts: 457
Likes: 1
From: Royal Oak Michigan
Well I finally replaced my alternator on Thursday night. Checked the output at the alterantor and battery
Car running
Alternator: 14.4 V- and steady
Battery: 14.12 V-
and steady
Car Off:
Battery: 13.5 V
So I was happy as can be until Friday evening- went out to take her for a drive and nothing- same as before- hooked up the jumper cables and she fired right up.
Took the battery out and trickle charged it all night- Now everything is fine.
I think with all the rootcausing and my bad alternator I just ran the power out of the battery.
Still need to look at my Meter to see if I blew a fuse in it
Thanks for all the help
Darrel1
Car running
Alternator: 14.4 V- and steady
Battery: 14.12 V-
and steady
Car Off:
Battery: 13.5 V
So I was happy as can be until Friday evening- went out to take her for a drive and nothing- same as before- hooked up the jumper cables and she fired right up.
Took the battery out and trickle charged it all night- Now everything is fine.
I think with all the rootcausing and my bad alternator I just ran the power out of the battery.
Still need to look at my Meter to see if I blew a fuse in it
Thanks for all the help
Darrel1