I have a 2007 Suburban LTZ with 333K miles that I bought in 2007 with 7K miles.

Back on January 12th, I came out to a completely dead battery. I drove it the previous night and had no issue. The battery is a 3 year old AGM with 30K miles. I charged it up and it tested out fine. Figured something got left on but I didn't find anything. I had been driving it daily with no issues until about 2 weeks ago. Drove my Challenger for a few days then went to drive the suburban a couple days ago and it was completed dead again. Figured maybe the battery was on its way out so I swapped over the month old battery from my truck to it and today, it's dead again. Only 5v registering.

I did some parasitic drain testing and after a few minutes, it'll drop to 20mA and stays around there. I spot checked it several times throughout the day and it's always around 20mA.

I replaced the radio with an aftermarket unit over a year ago and I did a custom HID lighting upgrade several months ago. The radio is drawing almost nothing and the HID lighting is relay triggered when the headlights are turned on so it's drawing nothing as I would expect.

I suspect something is waking up periodically and drawing enough current to drain the battery after a couple of days or so of not being used. I've seen this happen with other vehicles with onstar type systems when they can't phone home.

With the sunset of 2g/3g as of the first of the year, I'm wondering if this is an onstar related issue.

Has anyone else noticed this happening as of the first of 2023?

I really need to do some overnight current monitoring so I have a couple different current monitoring devices coming that I can interface with an esp8266 or esp32 and transmit real-time data to my server for analysis. Hopefully I can catch a consistent current spike and if so, I can start monitoring individual fuses until I find what's causing it. I thought about hooking my scope up to overnight it but it needs to be hooked up to a pc and I'm hesitant to leave my laptop in my vehicle overnight.

 

Why not remove like a quarter of the fuses overnight until the drain stops and then concentrate on those circuits? Just a thought. Cheers. Wavelength.

 

I've been monitoring it for almost 3 days now using am INA219 and an ESP8266 and there has been no unusual drain occurring. I'm averaging about 35 mA which is perfectly normal. One to three times a day, there will be a spike up to 200 mA for just a couple seconds which is nothing of concern.

So far, I'm not seeing anything out of the ordinary. We haven't been using it while monitoring because the INA219 can only handle 3.2A and it needs to be inline between the positive terminal and positive wire to work properly. I need to do monitoring during normal use to see if I can catch anything. I have 500A SmartShunt coming that writes data over Bluetooth for later visualization. It also has a UART so I will be attaching it to an ESP8266 so it can capture data every second and send it to Home Assistant for alerting as well as write data every seconds to my InfluxDB. I can then create some graphs with Grafana for better visualization of the data.

Here's the data from the ISA219. You can see the 200 mA spikes and the battery drain is normal. There is a momentary voltage drop when the current spikes to 200 mA but it's obscured by the current reading. It then jumps back up to the previous voltage.

 

I don't think a 200ma spike a few times a day would drain the battery. Wavelength.

 

Have you tried monitoring the battery with it completely disconnected to see if it dies on its own?

 

The voltage drop in my graph is normal for the 35 mA draw.

When I first found it dead, I charged it fully and spot checked it over the course of a couple days while in my house under constant temperature and it remained steady. Since it happened with two different batteries, I'm sure it's the vehicle. The park assist module has been having issues so I'm wondering if it could be that. I'm not sure if it's powered while the vehicles if off, however. It's been raining for a couple days so I haven't had a chance to do anything else with it.

I did end up removing the current monitor because we need to use it for towing this weekend. I had ordered a SmartShunt but I found out the serial interface isn't currently supported by the firmware so I cancelled it. I may get a Victron SmartShunt. It's well supported and they have published the UART specs so I can monitor it real-time over Wi-Fi. I currently have a Bluetooth voltage logger attached but it only logs ever 1 minute. It's real-time when viewed in the app via Bluetooth.

 

It looks like this has something to do with leaving the vehicle unlocked. It eats up over 1v per day when not locked with the fob. Just locking it from the inside door switch is not enough. I'll be doing more testing in the morning to try to determine what's drawing the power.

Since my wife uses it to tow a camper that has lighting inside, I've already installed a second and isolated battery. I even moved the radio over to the second battery because I found that it was drawing .20mV all the time. That's not much but it's 1/2 of the total draw when all modules are asleep/

There is a TSB for a battery drain but mine already has updated programming that would cover that.