I have a 2001, 6 speed convertible. Last Friday I went to start it and it was dead, no lights, no horn, no nothing. Put a new Interstate battery in it yesterday. Started right up. drove it on & off all day. Went to start it this morning, nothing, dead as a rock. Anybody have any ideas ??

John

 

Whats the date on the new battery?

 

You've got something stuck on. Could be as simple as the little bulb under the hood. Or in the glove box.

I'd try parking in a dark and quiet garage, may make the sleuthing a lot easier. Could be a tricky thing but sounds like it's not intermittent at least!

 

A brand new battery completely dead after one day....Umm, I would look at the alternator? What killed the first battery. Charge the battery turn the car on and see if the alt is charging.

 

You may have a power drain. There are a number of things that could do it. make sure that none of the seat adjustment buttons are being accidentally held in the on position. make sure none of your lights (including interior) are staying on. There are other possible power drains as well. There is an outside chance that your alternator has gone bad. you can use a voltmeter to test it while the car is running. Have you tried jump starting the car with the new battery in it? If you can get the car running you should be able to see both on the guage as well as in the DIC what battery voltage is being put out. Again, my bet would be a parasitic power drain somewhere. Good luck tracking it down.

 

Not may.... You do!
Now the challenge begins. Finding the RW... right wrench. 🙄

 

If you are not electrical savvy to use voltage meter to sort out voltage drainage issues (BTW, I am not) and making sure you have not left anything on in the always on mode sockets (i.e. cell phone), my suggestions for a DIY is: 1) pull one fuse at a time that is associated with stuff on the car that can be turned on without the key such as power seats, headlights/fog lights/interior lights. If after going through the pull fuse process for each one to sort out the problem and still having battery drain, put a kill switch on the negative battery cable when parked until you can take it to someone that can do the diagonals of the issue.

 

It could also be that the battery, while new, was sitting on a shelf for a while. Same thing happened to my parents in one of their cars. Left the new battery on a tender for a few hours since this car takes a lot of short trips and there has been no issue since.

 

I doubt very seriously a bulb under the hood, or in the glove box would take a new, fully charged Group 78 battery to totally dead in 12-18 hours! I do agree he has something drawing the battery down. My 2000 C5 did this years ago, and it was a bad BCM. But a bad seat control module, or some other module in the car, could also do it. If OP has a voltmeter, there are threads here that can help him. Anyone who owns a C5 should become familiar with 2 very important things:
How to use a voltmeter, and
How to pull codes from the DIC......

 

Here's a few things that you checkC5 battery drain. Checking current draw.
For those of you who have C5's that have problems keeping the battery from going dead if you leave your car idle for a short period of time, here is a procedure that you can use to see if your car is drawing an excessive amount of battery current. The C5 corvette should be able to sit idle for weeks without running down the battery far enough that it will not start.

If your car has a good battery and it depletes the battery in a few days or a week, use a DC Amp meter to measure the battery current draw when the car has entered the BCM sleep mode.

Once ALL of the cars loads are removed (i.e. doors shut, trunk shut, interior light off, radar detector and phone chargers removed etc, (make sure that you disconnect the under hood light), disconnect the battery NEGATIVE terminal. Connect a DC AMP METER capable of reading at least 10 amps in SERIES with the NEGATIVE battery terminal and the NEGATIVE battery cable. Once you connect the amp meter into the circuit, the car should power up and enter the "SLEEP MODE" within a few minutes. It should not take longer than 10-15 minutes. If the car is in the RAP (retained accessory power) mode, it may take that entire 10-15 min to power down.



Battery drain test with more detail




The battery cables MUST be properly torqued to the battery with a torque wrench to 11 FT/LBs. If you can ever move the terminals by moving the battery cables, the terminals are NOT tightened properly.

Remove them, clean them and re-torque them on the battery.

BC









When you initially connect the AMP meter in the circuit, the current draw will be high. Somewhere around 8 amps. As the BCM determines that the car is secure, it will start dropping off loads and go into the SECURITY MODE and Sleep Mode. As it drops off loads you will see the battery current drop down from 8 amps to around 2-3 amps them in the milliamp range.

If there is a unwanted load, it could take up to 10-15 min for the current reading to settle out as low as it will go. The target reading will be 15-20 milliamperes. As you can see in the next photo, my 02 ZO6 draws .02 or 20 milliamperes.



With this small current draw and a properly charged battery in good condition, your C5 should be able to sit idle (without a battery tender or battery charger) for at least 3 weeks if not longer. My ZO6 has set idle for 30 days and started normally after that period.

C5's that drain batteries in days or a week have an excessive battery current draw issue. Here are a few places that have proven to be a cause of excessive battery current draw:

1 Drivers or Passengers seat control multifunction switch. The return spring in the switch gets weak or damaged and the seat sticks in a movement position. The motors are thermally protected by a "circuit breaker" in the passenger’s foot well and will continuously set and trip until the battery goes dead.

2 Driver’s LUMBAR motor. Same as above!

3 Interior lights, dash lights, or other interior lights.

4 Head light motor control module. The module can short inside and draw current even though the lights are down and secure. If you feel the module and it’s HOT, it’s bad.

5 Alternator. The diodes can and do go bad. If they go bad, the field windings will always be powered and draw current. If you suspect that the alternator is drawing current, remove the field terminal wire from the back of the alternator and insert the AMP Meter in SERIES with the circuit (between the red wire and alternator field terminal). The current draw should be ZERO. If you have current draw, one or more diodes are bad in the alternator. The last alternator that I checked this way was drawing 5 amps.

6 Bose Amplifier. There’s an amp under the dash on the driver’s side dash. The relay for that amp sometimes sticks and the amp remains on even though the car is OFF.

Cell phones, radar detectors, wide band controllers etc... can get left plugged in.

NOTE! If you open the door, or trunk or even remove and then replace a fuse for troubleshooting, it will wake the car up and you will need to wait for it to enter the SLEEP mode again to read the current draw.

If you remove a BCM fuse, it will negate the test because the BCM is controlling the current draw.

Hope this helps figure out the reasons for premature battery failure.

Bill Curlee




Here is a portion of a post by Bill Curlee, the Forums resident electrical wizard:

The correct BCM current draw should be 30 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.

Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendency stay on
and cause this issue.

Also pull the fuses for the Bose system amp.

Examine the car in the dark for lights staying ON.

Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.

Look at my electrical stickey. I think I cover this in detail in that post.

There are several COMMON things that cause excessive current draw

-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off

And here is Bill's thread on how to further narrow down a current drain:

http://forums.corvetteforum.com/1567522286-post590.html





One common problem with unknown battery drainage is; the drivers seat adjustment switch. I had this problem too so as test I unbolted the seat to get access to the bottom and disconnected the harness.
That solved my problem. Be sure to adjust the seat to your liking before you do this



Found out the battery had a bad cell..

 

I would jump the battery and start the car. If your alternator is good, then the engine will keep running when you unhook the jump pack. This is a trick to see if alternator is good. If you want to be certain before changing it out, then hook up an inductive Amp meter to see if the charge current is good. Good news is alternator is easy to swap out.

 

BOTTOM LINE! You HAVE to get you hands on a Multimeter. If you are NOT TESTING, YOUR GUESSING!
FULLY RECHARGE THE BATTERY! If you are unsure that its good, have it fully tested at the Parts Store.

Start the engine. READ the battery voltage at the battery terminals. Should read 13.5-14.7 VDC (Engine Running) Compare that reading with what you see on the DIC Digital Voltmeter ((on the IPC) and on the Volt Meter gage on the IPC. (list the three readings)

NEXT and probably the most important; Conduct a Battery Current DRAW TEST. Disconnect the NEGATIVE battery cable. Place a 10 AMP capable Amp Meter in series between the battery Neg Cable and the NEG battery terminal. WAIT at least 12 MIN for the car to fully go to sleep! With the BCM in Sleep Mode, You should see very close to 0.025 - 0.030 milliamps. High current readings indicate something in one of the two fuse boxes is drawing excessive current.
You could still have a bad alternator diode which would let the alternator take a LOT of current from the battery when the engine is OFF. Feel the alternator and see if it is WARM (cold engine) To test for a bad diode, DISCONNECT the large red BATT wire from the back of the alternator. Install a 10 Amp capable AMP Meter between the removed RED wire and the BATT terminal on the alternator. The correct reading should be ZERO AMPS. Any reading of current draw will indicate that the diode/s in the bridge rectifier circuit are leaking and require replacement.

BC

 

Check the wires to the starter. If loose, voltage will drop, battery won't charge from alternator, all sorts of bad ****.

 

12 good answers and crickets from the o.p......

 

My drain was the OEM radio. Had the same issue with a Delco stereo in both my '97 Regal and my '07 Hummer

GM head units from this era just seem to take a poo on me I guess!

But given the history I've had with them, when my C5 was dumping the battery, first place I looked- radio. Pulled a constant 1.8amps thru the fuse with the vehicle off and everything else powered down

Left the fuse out as a sanity check, car sat for almost 2wks at 12.2v consistently on the battery

tldr- check the radio for draw