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Leaving a 12 volt battery alone overnight should not drain it more than a certain amount. The reading on my BM2 battery monitor was 12.53 volts yesterday afternoon and 12.42 volts this morning. I recently purchased a brand new Yuasa 50Ah agm battery in April.The battery seems to drain quickly, so I'm not sure if it's functioning properly.

I unplugged mine after purchasing one; the 45Ah 12v Auxiliary battery it came with showed worrying voltage drops in just one day. Even if it's true, I'd rather not worry about checking the battery every day and instead charge it every two weeks if I haven't driven the car .

Factory batteries aren't designed to handle cars that aren't driven every day or even multiple times per week, and the bigger battery just changes the intervals before it discharges, so all you're doing by replacing them with 54Ah is putting the problem off until later.

I get it; it just makes things worse. I guess you can't worry about things you can't see.

To keep the battery charged, my neighbourhood dealer actually sells solar chargers. So it's clear that something is wrong.

my 2022 gr 2lt is comparable to that. If you want to put your car into a sleep mode that searches for a key, etc., by pressing the lock button three times on the remote, as I have done, it takes less than an hour for the battery to discharge.

Is the weather being considered? The voltage may be affected if the battery has gotten cold overnight.