Just bought 40th Anniversary car. PO said he has a parasitic draw. Battery goes dead every couple days.

Couple of thongs I've checked or noticed.

First I fully charged battery reading was 13.03 to 12.97
second I made sure car was locked over night at least 24 hours of sitting still

Battery reading this am was 12.69

I disconnected neg terminal and placed my MM on 5 amps and checked between battery terminal and cable and found .33 amps. Is this acceptable?
as soon as I touched the probes and made a complete connection the bad headlight motor spun for a couple seconds and then shut off (bushings bad)

Battery shows a 6/17 date so about 3 years old Exide from Walmart. After getting an amp reading then I rechecked voltage at battery because headlight motor used some volts to spin. Battery voltage showed a drop from the 12.69 to 12.55

I think I should pull the battery and take it to advance auto parts and have it tested as a start. I don't have FSM and placed a WTB on the forum. My 94 manual is different some OBD1 and 2 and different terminal

I've read just about every post on draw on this forum.

I can say I wanted till 11pm and went out and peered into the car and did not see any lights on including but couldn't open glove box or sun visors.

If battery checks good then I'll start by opening pass door and make sure I use a board and clamp to push in the door switch and start checking fuses.

If anyone thinks I should be going about it differently or has experience trouble shooting parasitic draw please chime in. Love the Ruby Red car!

 

.33 amps draw is too high.

 

Pulling one fuse at a time, and checking to see if the .33 amp reading changes has proved useful.
Some fuses protect more than one circuit, so it isn't always easy to determine the parasitic draw circuit.

(drove my ruby vert for 12 years - only 1 opti change - beautiful vette)

 

.25ma is the max draw back then. def need to pull the fuses one at a time then check your reading each time

 

The reading should be less than .50 MILLIAMPS.

 

I pulled the Walmart Exide battery with a date code of 6/17 and took to Advance Auto Parts I ran the test it came back bad battery. It showed 12.74 volts but said battery wouldn't hold charge it was defective internally.

I bought new Diehard and am charging slowly. Will install but not start car. It has two fuse blocks inside the engine base. I'm used to seeing fuses on side of dash passenger door??

After reading this post do you think I've found the problem or will have to investigate further??

 

You have solved one problem (battery), but you will have to wait until all systems are ready for test.

 

Once battery fully charged I'll install with positive attached then put MM probes on neg post and cable and see what's what

So cool really appreciate everyone's help.

 

Reminder: WHENEVER POSSIBLE, CONNECT THE METER ON THE GROUND SIDE OF THE CIRCUIT. It’s the same reasoning you employ when, while replacing the battery, you should always disconnect the negative terminal first and connect it last. For a current measurement, the meter will be in series with the circuit, so the probe leads are as live as any wire in the circuit. If you connect the meter on the ground side of the circuit, completing the circuit to ground will cause power to flow if the circuit wasn’t turned off, yet it can’t cause a dead short of a live power wire to ground because the meter is already on the ground side. In contrast, if you connect the meter to the positive side of the circuit and accidentally touch a probe lead to ground, it’ll cause a dead short of power to ground, which is sure to blow up the meter’s fuse or the meter itself.

 

sorry Don I mislead you. The positive cable is connected to the battery. I will leave negative unbolted and place the probe on the negative cable and the other probe on the negative battery terminal.

I am hopeful to see less than <50 milliamps

 

Sorry Don, but that should be less than 50 milliamps (0.050 Amps)

 

Thanks, Roy. When you are 88 you shouldn't use decimals.

 

well after installing a new battery fully charged I checked the MM and got the same reading when I put it on the 20 scale it read .033

I connected the negative cable to the battery and started watching the volts over the course of 15 minutes it went from 12.71 to 12.56

so I disconnected the negative terminal will go back at it tomorrow.

before connecting battery tomorrow I'll open passenger door and clamp a thin board to the light switch to keep it deactivated and lay the MM on the windshield and start pulling fuses one at a time hoping one will make the meter go to zero or something minimal.

Thanks to all who are lending a hand. I love this forum and of course Corvettes.

 

Isn't .033 amps equal to 33 milliamps? Which is within specifications. I think the car is fixed.

 

on the MM 2M scale I'm reading .029-.030 seems like in limits!

I pulled each of the mini fuses inside the car and none had any affect on the milliamps.

Since the previous battery was bad I am gong to install the negative lead on the new battery write down the voltage and let her sit overnight and recheck in the am

If the voltage has dropped significantly then I'll start checking the maxi fuses in the engine compartment if they're good pull the headlight control module basically keep looking.

I did observe a slight spark or arc when touching the neg cable to the battery. Does this indicate that their is more than aminimal draw on the battery?

 

This is from the factory manual when i was at the dealer 25ma was the normal max 50-75ma was for vehicles like cadillac's that has more electronics and computers.

 

would u be concerned about the arc or spark when I touch the neg cable to the battery

 

there is always going to be a little spark. does the battery go dead over night?

 

Firefighter thanks for all the help.

All mini fuses were ok. I pulled the Maxi fuses and found the the accessory 60 amp fuse when pulled the meter went to zero. All accessories work as they should so I connected up the negative to the battery and noted the voltage reading. I will go out in am and check voltage . If it's only down a little like 12.2 from 12.44 then I think I'm ok and the battery was at fault with a bad cell.

 

Here's what I found.

On the Maxi fuses the 60 amp that contols the Power Accys when pulled the meter goes to 0 milliamps

Pwr Accy are seats, pwr door locks, radio and rear hatch all are working fine and none of the mini fuses connected with the those when pulled showed no affect on meter reading.

Last night battery read 12.44 volts this morning read 12.24 volts.

I am thinking the .032 milliamps is fine and suspect the alternator is overcharging and in the old battery may have damaged it internally thats why it showed good voltage but ability to retain charge over the long haul. JMOO

Started car and it was charging at 14.4 volts after about 3 -4 minutes it still remained at 14.4

Even though the battery was a little low at 12.24 I don't think the alternator should be charging at that rate. Maybe I should let the car run for 15 minutes and see if voltage drops down to like 13.2

I am beginning to suspect the alternator. I think it's charging at too high of a voltage. I think it cooked the old battery causing internal damage which is why it showed 12.7 volts but had no capacity to hold a charge for a couple days.

Just my opinion but since this new information has been detailed wonder if anyone can chime in with their thoughts? Thanks feel like I can see land now LOL