But it was a result of faulty wiring.

 

My 2025 Stingray ticks along at 12.1V according to my CarLock device. I did get a couple of low battery alerts early on with it, but that seems to have stopped now. When I got the alerts, the car would still start normally, but it would not perform an OTA. I put it on the battery tender overnight and CarLock read a higher voltage and the OTA worked fine.

 

FWIW checked on the standby current draw ans it says it's only ~2 milliamps. That is low. BUT noted in another discussion what I had mentioned Corvettes are known to completely drain the battery on over the air software updates. Those appear to NOT allow the parasitic reducing circuits to activate. Andy's 10 milliamp draw is ONLY after all circuits have activated. Much higher prior.

Assuming you don't have an amp meter as a minimum with the devcie connenected and not test the Frunk, Truck, Map Lights with the devcie inserted in the OBD port and NOT. There are othe line sone V4 defeat devcies that plug into the OBD port that drained the battery. Folks removed each time they stop.

 

@JerryU where did you find the standby draw for the CarLock. I could not find it. But that is plenty low. He has other stuff connected too though.

Yes, the 10 ma is after all of the car system go into a sleep mode. I do not know the technical term that GM uses for that condition. I only know that I observed the shut down in the form of current draw reading, and watched it drop down in more or less discrete steps. Dropping from 10 amps to 10 ma.

 

^^^^

Google Found:
Is CarLock draining the battery of your car?

CarLock SupportThe CarLock device has different power saving modes, so when the car is idle, it will consume only around 2mA. Even if your car is idle for a couple of weeks, there should be no problem.

BUT key question, does being Plugged into the OBD does it block some of the Parasitic reduction circuits. I do recall one of the V4 defeats that plugged into the OBD did and a poster said they removed when they parked!!

 

Fuses
There are fuses inline for the 2 Bluetooth controllers and none for the CarLock (didn't come with one). Maybe the draw doesn't warrant an inline fuse? Maybe it's inside the device (well, that would make it hard to change)? I can ask them because now I'm curious.

Draw
Yeah, the controllers are listening for Bluetooth connections at all times since they are always on and powered by the battery. So that will add some draw. I can ask CarLock what the draw is on their device to confirm Jerry's search result, but it might be hard to figure out for the controllers... I will ask Oracle but the other one is some off-brand that came with a kit I purchased from Custom LED Service and I may not be able to figure that one out.

This is good to hear - can you check if this is the case right after you shut the car off? An hour after? A day after? I would love to hear if you see similar results as me because your battery should only be a year old or less.

Update on My Battery
Car is at ~13.28V on the charger. It's a 1A charger so it's expected to be slow. I'm waiting for the charger to go into maintenance mode (flashing red LED turns green) before I disconnect it to see if there's any loss of charge without the negative terminal on. I have this LiFePO4 battery in my Amazon cart that was discussed in this thread by @dstewart51 . I can go ahead and buy it now to be safe since it is an eventual cost I will have to incur, but I am curious if we will see similar results (voltage readings) with a lithium ion battery. I made a thread on AGM vs LiOn for my replacement and decided on LiOn because there's really no reason not to. I still need to tell CarLock what voltage minimum to set; leaning towards 11.5V at this point because whether it's lead acid, AGM, or lithium ion, that seems like a cause for an alert notification. While everyone has a lot of apprehension about my battery's life (reasonable given the usual C8 stock battery lifespans), I would like to get to a definitive conclusion before tossing the battery just because I can as a preventative maintenance. It would make me feel better and also mean I can figure this out in the future on my own or if someone else needs help (who may not be so eager to drop $300 on their car for something they may not need).

https://www.corvetteforum.com/forums...ttery-way.html

 

The best way to get definitive proof is to have it load tested. They take a look at the voltage under a heavy draw, and how the voltage drops under heavy load.

Voltage is useful..to a limited extent...for evaluating the state of charge of the battery. And it does drop some as the battery ages - the voltage you reported, 12 V is low and indicates a low battery. But a key cause of failure is if/when the battery develops higher than normal internal resistance. With no current draw, that will not necessarily show up just by checking battery voltage. Under a heavy load, if the battery has a high internal resistance, there will be a significant voltage drop. And that is what you want to find out. And the result is definitive proof, short of a hard failure in the field.

As for the 11.5 volt threshold, if you see that, the battery is already dead (0 state of charge). And the car probably wont start.

 

You need a new battery (third time saying this).

 

I had the battery out for the past few days and charged it to ~13.2V with my NOCO Genius 1, then disconnected the charger and let it sit in the house just to see if it would discharge on its own.

5/19
10pm - 13.10V freshly disconnected from the charger

5/20
2am - 12.90V
11am - 12.84V
11pm - 12.83V

5/21 today, 3PM I took it to Advance Auto Parts and had it load tested. It read 12.83V and tested perfectly. However, I did buy a LiFePO4 battery just in case this one was bad. And now that I'm reading the comparison of which one I should use, there's really no reason to throw the lithium in the car at this point:
-

1. I already paid for it, and could let it sit on a shelf safely but what's the point really? As pointed out, the 5-year battery might cause problems if I rely on it and with my extra parasitic draw, it's a pain even sitting between weekends. No reason to put inferior technology back into the car.
2. I can test it out and hopefully not have a different experience than the guy who has been having a great one with this TPE lithium battery... the FLA will be here if I do to get me by, while I probably just get an AGM and give up on lithium. Not paying $1200 for an Antigravity lithium so it's up to you, China!
3. I can solve the original issue of low voltage alerts and in fact probably crank them up to 12.8V based on my research. The voltage of lithium is quite different than FLA:

 

Agree. Based on the chart you posted, when you install the Li battery you want to be alerted when the resting voltage drops to 12.8 volts. I don't think you will have any issue.

Many have successfully dropped an Li battery directly replacing the OEM FLA battery - and it does not require any changes to the charging system. Many are designed specifically for that. You should not have any issues, but you will not necessarily see the voltages you expect, because the charging system in the car is is designed to charge an FLA to a state of charge of 80% (based on the Service Manual description) so its not going to charge the Li battery to 100% SOC. Based on forum reports of successful use of Li batteries in the OEM system, it does not hurt anything - but the voltages may be a little lower than you expect if you are basing it on 100% SOC numbers in the Li chart. Still....it should not drop to 12.8 v, so I think that's ok as a threshold for your add-on device.

The Stingray car charging system is designed to charge the FLA to 80% or so, based on the Service Manual description. And the resting voltage for an FLA at 80%, is around 12.41 volts. The target charging voltage, when the engine is running, is higher than that, of course. And, it is complicated by the fact that the the charging system has other charge modes, with a higher charging voltage, that will kick in when the headlights are on, or HVAC fan is on high, or windshield wipers on on, or battery is cold, or vehicle speed greater than 90 mph, and there is also a sulfation (actually desulfation) mode (see attached description). So it can charge the FLA to more than 80% at times, and in practice forum members may report seeing FLA resting voltages higher than 12.41. (all of this is why I don't look at battery voltage - its a rabbit hole).

The charging system does not know that your new battery is a Li battery, so it estimates the SOC assuming its an FLA (as far as we know). When the charging system in the car determines that the battery state of charge is 80% or more, it is going to enter the Fuel Economy Mode under many conditions and maintain a charging voltage between 12.5 and 13.1 volts according to the Service Manual description. Compare this to the charging profile for the CTEK Lithium US charger that is designed to charge and maintain an Li battery to 100% (attached). During charging it maintains a voltage of 13.8 volts, peaking at 14.4 volts, before entering a float phase where it maintains 13.6 volts for an extended period. These voltages are higher.

So, while you should have no trouble with the Li and you should not be dropping below 12.8 volts, I don't think the car will generally charge it to 100%. That is not a problem. In fact, its probably a good thing. Most sources say an Li battery should not be maintained at 100% SOC.

Here is the charging system description from the Service Manual. I think it is similar or the same across other GM cars and other model years too.

"Charging System Modes

Battery Sulfation Mode

The BCM will enter this mode when the interpreted Generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2 - 3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.

Charge Mode

The BCM will enter Charge Mode when ever one of the following conditions are met:

• Windshield wipers are ON for more than 3 s.
• Climate Control Voltage Boost Mode Request is true, as sensed by the HVAC control module via serial data. High speed cooling fan, rear defogger, and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
• The estimated battery temperature is less than 0°C (32°F).
• Battery State of Charge is less than 80%.
• Vehicle speed is greater than 145 km/h (90 mph)
• A current sensor malfunction exists.
• System voltage is determined to be below 12.56 V

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9 - 15.5 V, depending on the battery state of charge and estimated battery temperature.

Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 A and greater than -8 A, and the battery state-of-charge is greater than or equal to 80%. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5 - 13.1 V. When fuel economy mode is active, the generator is not charging, only maintaining open circuit battery voltage. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.

Headlamp Mode

The BCM will enter Headlamp Mode when ever the head lamps are ON (high or low beams). Voltage will be regulated between 13.9 - 14.5 V.

Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 s."

Below, for comparison, is the charging profile found in the manual for the CTEK Lithium US charger, that is designed to charge and maintain an Li batttery at 100% SOC.

 

@Andybump I appreciate you sharing your wealth of knowledge here. That's good about the 100% charge - I have a Bolt EV and many owners do the "40-80%" rule when they can even though most EV owners just let it fully charge and perform its maintenance cycles. I charge my car probably once every 3 weeks because I work from home and don't go out much, but I try not to run it into the ground and think they battery conditioning at full charge is more beneficial than the "added wear" of topping it off. From what I'm seeing, nothing will be different for me using the new battery other than the voltage to tell CarLock to monitor.

Lot of good info in here and I've learned a lot! Specifically, FLA batteries are just more problematic and Lithium or AGM is the way to go.