Originally Posted by Bill400

@guy Thanks,
The vast majority of electronic problems with our cars is correctly summarized: "It's the battery!".
No OEM voltmeter is provided. Xks tend to be garage/driveway queens, not driven daily, so low battery voltage is likely.
For many folks, the battery test is start/no start. When battery voltage is low but sufficient to start, the problem goes unnoticed until it presents itself as a module fault, seemingly out of the blue. The problem is accentuated, I believe, by marginally performing new batteries.
If a battery is less than 100% charged (say 12.4V) when installed, will the battery monitoring system (BMS) of 2010 and newer models prevent it from ever becoming fully charged? My understanding is that the BMS will properly reset over time. Maybe too long and battery never recovers?
The service manual battery section, previously attached, is good but maybe it's time for our brain trust to cobble together a proper document.