05 CTS-V battery drain?

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

Re: 05 CTS-V battery drain?

Post by kevm14 »

It finished within the next hour of posting that, settling on a lower maintenance voltage of around 13.2V.

Before I connected it, I used Adam's micro-load based (micro-controlled) tester. It said like 98% charged (makes sense) but like 53% capacity. Then we did some tests involving connecting the battery to the car. Voltage dropped to like 9.8V while cranking which is on the lower side of normal even though the starter sounds pretty normal to me.

I reconnected the amp and put that all back. I also reconnected the charger so we'll see how that behaves. Adam thinks it's just a crappy cell in the battery and I should just buy a new battery. Probably good advice. What I am trying to avoid is deep discharging a brand new battery which is why I wanted to determine if I have some parasitic draw. Based on everything we saw, and that the battery is pushing 9 years of service, I'd say it probably just needs a new one...

Unfortunately I lost my G meter peaks and stuff. Wah. I guess I'll update when I replace the battery or disconnect it for the week to see if it drains (it may not even though it could be bad). It takes a group 101 which is an uncommon size. 650CCA which is on the low side if you ask me but that's what it specs (and honestly what fits).
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

So as I said, last night I connected the charger (Battery Tender) to the battery after reconnecting the ground terminal to the car. This morning the charger was on green indicating a complete cycle and that it had entered the maintenance voltage. That wouldn't be possible if there was a drain in excess of ~1.25A. Here is my current theory:

- Battery was getting weak. I may recall slightly weak cranking when I drove the car in that week in April, now that I think back. Nothing bad but I did notice that it sounded a little different. This would have been a clue.
- I let it sit probably 4 weeks with no charger which would NORMALLY be totally fine.
- It had probably drained to a low level at this point, or one cell had pulled the others down.
- When I connected the charger, it did not have enough current to actually get the chemistry going again (so to speak)
- After disconnecting from the car, it did charge but it took like 3 full days. My first thought was the battery had plenty of capacity. More likely (and sort of validated by the battery tool), a cell is bad and effectively causes an internal drain or resistance that works against the charger.
- The car may do something undefined with an extremely drained battery, that may present like a parasitic drain when it's really the battery that is out of spec. If you read the forums, these cars (and I think the STS even more so, with its 23 CAN modules) really need a good battery or else weird stuff can happen. Again, this battery is approaching 9 years in service (rated for 6 years).
- Once the battery was charged, the voltage was again in spec, the car modules booted up, did whatever routine they have, and then enter a sleep state, and everything was happy. The charger was able to complete its cycle since the battery was recently charged.

In summary: Probably don't jump to electrical conclusions when you have a battery that is likely bad. I don't think there is anything wrong with the car. But I may still get an inductive ammeter (with the new battery) and see what kind of draw it does have ~20 minutes after shutdown or whatever. It is probably fine. The FSM should have specs on that.

Also, when Adam and I were messing around with his battery checker tool, when I turned the key on, the audio system came up and worked fine, by the way. So I also don't think there's anything wrong with the amp...

Other conclusions: My cheapness combined with my willingness/interest to jump into diagnosis mode sometimes works against me. In the end I don't really care as it always becomes a learning experience, which I embrace.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Someone on the internet says a group 78 will fit though it does not appear to me that any additional height is possible. Napa specs say it will be 0.562" taller. The cowl cover seems to lay directly on top of the battery. I think that is out but I'll do more research. Too bad because a group 78 is WAAAY cheaper. And has more cranking amps.

Apples to apples. Napa Legend.
Group 78: https://www.napaonline.com/en/p/NBP7578
Group 101: https://www.napaonline.com/en/p/NBP75101

$131 vs $210. Yeah. Or I can get a group 78 in AGM for $198 at Advance before a 20 or 25% coupon. That would be the way to go if I thought it would fit. I don't think it will fit.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Wow I think there might be just enough height clearance.
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If the battery is returnable I see no reason not to try the AGM group 78.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Got a 25% off coupon for Advance.

Looks like $180.88 and then I get $22 back when I bring my old battery back for a total of $158.88 which seems pretty good for an AGM.
Adam
Posts: 2240
Joined: Wed Oct 23, 2013 9:50 pm

Re: 05 CTS-V battery drain?

Post by Adam »

Did you replace the battery yet?
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Ordered the battery (AGM group 78, hope I can jam it in there). Will pick up on my way home. Maybe I'll even put it in tonight.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

Battery info and specs. Factory group 101 was 650CCA.
Specifications
Amp Hour: 60.0 AH
BCI Group Size: 78
Cold Cranking Amperage: 740 A
Cranking Amperage: 925 A
Negative Terminal Location: Side Right
Positive Terminal Location: Side Left
Reserve Capacity: 115 min
Terminal Type: Side Mount
Voltage: 12.0 VDC
Product Details
Part No. 78-AGM
Warranty Details (3 YR FREE REPLACEMENT)
Autocraft Platinum AGM (Absorbent Glass Mat) batteries are specifically designed for today's power hungry vehicles. Autocraft Platinum AGM batteries are engineered to provide up to 2x the life vs. a standard flooded battery. This battery is ideal for vehicles with electrical accessories (DVD players, heated seats, GPS, plug-in accessories) which put a heavier demand on the battery or vehicles with start-stop technology. Autocraft Platinum AGM batteries are engineered with PowerFrame grid technology, a stronger and more durable positive grid technology.

Product Features:
Up to 2x the life vs. a standard flooded battery
Designed for vehicles with high electrical demands or accessories and vehicles with start-stop technology
Non-spillable design allows for installation in any location, including in-vehicle
Robust design offers exceptional high temperature climate performance and the most reliable starting power in cold conditions
Higher level of vibration resistance compared to standard flooded batteries
Engineered with PowerFrame positive grid technology which virtually eliminates premature failure and is up to 66% more durable and more corrosion-resistant than other grid designs
PowerFrame grid technology provides superior starting performance with up to 70% better electrical flow than other grid technologies. This means more consistent starts
PowerFrame manufacturing process uses 20% less energy and releases 20% fewer greenhouse gas emissions than other manufacturing methods
Built to meet or exceed vehicle starting power requirements
Maintenance free for maximum convenience
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

kevm14 wrote:This morning the charger was on green indicating a complete cycle and that it had entered the maintenance voltage. That wouldn't be possible if there was a drain in excess of ~1.25A.
Looks like my theory was correct. Got home, battery indeed still on green. But the charger was hot. It is never hot in the maintenance part of the cycle, which just maintains some modest float voltage like 13.2V. Should need very little current. So I'm thinking...well, there's either a drain on the car side that the charger is attempting to keep up with, or the battery itself has a bad cell and it is dissipating the energy into heat. One touch of the battery proved which it was.

My garage/objects were 65°F. Battery reading nearly 92°F. Theory confirmed.
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Old battery installed.
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Had to remove plastic cowl cover as if I was going to do the cabin air filter. That basically made the entire top of the battery accessible to pull straight up. Easy. Well, less easy without a handle.
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Group 78 installed. It fit perfectly in the tray and with the retaining clamp. Notice how close it comes to the plastic cowl cover. But it clears. Just. Unfortunately the insulated battery cover would not fit over the group 78. This is an AGM battery so honestly it is probably not needed.
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Look how close.
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Cables attached. Charger connected. Just for fun. Probably will be done very quickly. I did look it up and it is compatible with AGM chemistry. I guess I will test it with Adam's tool at some point just to see the result.
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The only fitment issue is this. There is not enough room to slide the weather strip all the way onto the cowl. So it will just sit on the battery over the last 6 inches or something. I think I can live with this. I have a higher capacity AGM battery for less than a standard chemistry group 101.
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Bonus! This battery had a date sticker that said 4/19 which is amazing. I read horror stories of 18 month old stock. Kind of sucks when the warranty is only 3 years. But I believe it is a full replacement. This should last at least as long as the AC Delco anyway.

The old battery is in the trunk so I will take the V in tomorrow.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 CTS-V battery drain?

Post by kevm14 »

As expected the charger was in full float mode having finished the charge cycle on the new battery. The charger was NOT hot when I felt it this morning. More confirmation of my theory.

No issues after the battery was disconnected for like a week. No key fob issue. No check engine or service-this-or-that warning. TPMS sensors transmitted tire pressures and the system began displaying the pressure with no issue. Only thing I had to do was relearn the auto-up front windows, which every single car with auto-up windows requires after the battery is disconnected. You just hold down the auto up until the window closes, keep holding for a second longer and you'll hear the window motor relay click off. It has relearned the motor current.

I did lose G-meter peaks and probably things related to the trip computer. Had to set the clock but because it's fancy, you can make it sync off GPS which I did, and that was done.

I just realized that the SRX also has an Advance Auto AGM (different group). The STS has an Advance Auto group 101. So apparently I'm all in on that...it helps that I find 25% coupons which is significant on a $200 battery.
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