I have a 2022 STX. I keep it on a Noco 10 battery charger/maintainer whenever I'm going to leave it parked for more than a day...Even after it shows to be fully charged if i leave it parked for more than 2 - 3 days it goess into sleep mode where nothing lights up in the cab when I open the door..I removed the battery charger and found the battery to be at 12.4 volts..Is my battery rreally low or not necessarily?

 

I've been messing with this for a few weeks, even though battery read fully charged on the charger, it still would go into sleep mode. Reset the BMS a couple days ago after fully charging and things are working normally again. Lots of You Tube or Google on resetting BMS, it's super easy.

 

I think if you are following that process and having such a quick drop 1 of 2 things is likely. 1 you have some form of parasitic draw or 2 your 12v battery is likely toast. I have a 21 and use the same NOCO charger every once in a while to top up the battery underhood and under the back seat. Our truck sat in the garage for almost 3 weeks while we were away recently before it went to battery save mode. The NOCO brought it right back up. Normally even with general use weekly I don’t see SOC drops of any significance and any drive of an hour or so brings any small loss right back.

 

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When the charger is connected, the BMS has no control of the charge rate.
When the Charger finishes its charge according to it's AGM Program, the Battery State Of Charge will be in the 13.6 +/- Volt range and Charger shuts off.
The Battery voltage will slowly drop to the 12.5 +/- range as the. Battery >Space Charge< drains off from the truck's sleep mode drain > and the BMS assumes control again< in about a 6 hour time interval, it accepts the Battery final State Of Charge.
12.4 Volts it settles to is about 70 to 80% full charge by design and intent of the Control system design. The SOC will continue to drop over time from the vehicle drains.
The less than 100 % SOC is a protection factor to prevent over charge heating of the Cells that are not to be charge above 14.7/8 volts an AGM requirement. The Cells are sealed and can blow open ( if) the Cell/s gets too hot and internal pressure build-up. Then the Battery is lost at that point.
Intent is to lengthen the Battery long term life by controlling these factors and the Charger is a Smart type, with an AGM specific Charge program.
There is a lot going on, more than just connecting a Charger, seeing the result and not knowing how it got there, and why.
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Good luck.