The little battery doesn't have a particularly high capacity many are replaced unnecessarily imho as they could be masking a potential different fault.
The cars don't usually have much of a parasitic load but this can increase significantly especially if an ECU crashes or hangs without shutting down and going into sleep mode.
Changing the battery effectively resets and reboots everything so masking the problem till it happens again
The later 2020 onwards 2nd generation cars have a battery saver option which helps but is not perfect.
I got into the habit of fully charging the battery in my 2016 car every couple of weeks if not being used.
I recently had an ecu crash in my 2020 car which I posted this about a couple of weeks ago on FB:
"
A different spin on a flat 12v battery.
Yesterday around 16:00 my BM2 app warned the 12v battery in our FE was down to 12v. It usually sits at around 12.8-13v permanently.
This is the first time in this car it’s played up.
I was about to swap it out with the virtually as new superior Yuasu battery I had taken out of our 2016 car before we sold it.
However I noticed from the app data the voltage was dropping rapidly suggesting a load.
The graphs from last night and this morning show how fast it was discharging after the charger stopped at around 22:00.
It was down to 10.5v by the time we went shopping this morning
I have just been out with my current clamp. Disabled the bonnet switch and locked the car, after a few minutes the current should drop to near zero. There was actually a constant 3-5A load on the battery something in the car had crashed and hung.
I disconnected the battery for half an hour and then monitored the current, it was behaving properly.
Earlier this week there were some odd symptoms rear doors didn’t unlock, key fob response erratic almost as if the key’s battery was flat. This morning I am almost certain the DRL didn’t come on….
It will be interesting to see what happens over the next few days the problem has coincided with the recent freezing weather and us using the remote climate command.
I had noticed the steering wheel heater had come on even though that option was turned off in the app.
If it wasn’t for the fact I know it’s voltages have been ok I would think the 12v battery was probably the cause of all this and on its way out but the symptoms initially suggest something else"
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