05 CTS-V battery drain?

Wiring, DIY, lighting, etc.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

05 CTS-V battery drain?

Post by kevm14 »

In some ways it is surprising that this hasn't happened more frequently since the car obviously sits a lot. I don't always have the battery charger connected though. The battery that is in it was installed under Cadillac CPO in probably late 2010 so it is pushing 9 years of service (it is rated as a 6 year battery). To be clear, what I'm about to describe has never happened...

The car sat for probably 4 weeks without a charger which I would think is OK. I decided to connect my charger last weekend. It never left the first charging stage (red light blinking). At some point I opened a door for some reason and....dome lights did not come on. Went on travel...left the charger on. When I got back, the red and green lights were flashing alternately. Never seen that before. Disconnected and reconnected last night. Measured voltage on battery (while charging) this morning and it was like 5.5V or so. Oh god.

Finally I disconnected the ground side to isolate the battery from the car and in only a few minutes of charging the battery, the voltage had risen to over 10.5V. So not sure what is going on but it seems like a drain. I think the last time I drove the car was to bring your child to work day. It would really suck if Ian left a light on in the back or something. I guess I'll charge the battery up (seems like it will take a charge, even though I'm sure at this point it is compromised), reconnect it, and sort of see if I can figure out what is going on. If it was just a battery issue (i.e. shorted cell) it wouldn't act any differently disconnected from the car. So it seems like something on the car side drained it. To be continued after battery fully charges.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Up to 12.0V.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

12.18V and climbing. It is taking a charge I think. Obviously it was deeply discharged. It is only a 1.25A charger which is quite slow. I mean the alternator on my Briggs twins are supposed to do 3A or so (into a small lawn & garden battery), to put that in perspective.

Very interested to connect the terminals back and see if a dome light pops on or something. Sigh. At least I hope it is that simple.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

12.32V
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

12.73V.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

13.40V
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

13.70V

Also I got impatient and touched the negative cable to the bolt I threaded into the battery ground terminal (which is how the charger is connected). When I connect it I get a spark. Also I heard a relay click from the trunk area. Battery voltage quickly gets pulled down below 13V which means the draw is in excess of the 1.25A the charger can supply (and maybe multiple amps). Keep in mind the charger normally works fine with the car fully connected so the parasitic draw should be substantially below 1.25A. I did not see any interior lights come on.

I managed to pop the trunk open with the remote while I touched the terminal to my bolt. With the trunk open the relay click was louder. Getting warmer. Then I pulled the left trunk panel and under that is...a Bose amp. I connected the terminal again and the click was even louder. So I removed the amp, disconnected the plugs and...no click from the amp but the battery voltage was still getting pulled down.

This is about as far as I got but I am wondering if something on the bus is not going to sleep or something. When the battery finishes charging I will probably connect it and probe fuses to see if I can isolate the draw to individual circuits and see if that leads me anywhere. I guess I could also just drive the car and shut it off again to see if something needed to reset...then there is the Tech 2 approach which may actually be quite helpful. Also, the test I did so far may be completely pointless. Why? Because the computers may all wake up upon initial battery connection. But they should go to sleep a few minutes later so what I really need is a good ammeter. I would connect it upon initial battery reconnection and then monitor for a sharp drop after a few minutes, which I would think would be normal behavior. My FSM probably has words on that actually. I will investigate.

I am going to bet that this is going to be something simple but I will need to go through a process to isolate it. I also need to keep the battery in mind before I go too crazy. It is still almost 9 years old. If I had a good ammeter I could measure real current flow instead of guessing based on battery voltage getting pulled down. I will try my fuse current technique with the table I posted in a sticky.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

14.25V, still in first stage. Probably due to enter second stage soon. Sheesh. Thing was dead.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Ha, just entered second stage.

Voltage is 14.27V. I think it switched from constant current (bulk charge) to constant voltage mode for absorption.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

14.395V. Still not done.
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