Problem with the Batterie

hello everyone, i have the following battery problem: my old yuasa ytz12s broke down in winter due to charging too often. I don't know how old she was either. I have now bought another agm battery. 12V 11Ah 140A. I fully loaded and connected it. After a day it was empty. I thought it was defective and exchanged it, but the new one had the same problem. It also only cost 40 euros. Is the battery bad or am I doing something wrong?

greetings Kismet

Hi Kismet.

Sounds to me like you have a parasitic drain on the battery when left idle. But was the bike being used or parked up.

If parked up then the .....
Most common fault is the underseat light switch, which sticks on when the seat is closed, remove the bulb over night to confirm.(will flatten a battery over night)

After that your down to using a Multimeter on the battery feed to test for a drain somewhere.

If being ridden then..
It will be your voltage regulator gone down, located behind the headlight unit. Quick test of the battery voltage while running should show 13/15 volts,
12v or less means no charging from the regulator. Not read of an alternator ever going down, changed a few regulators though.

Hope this is of help to you.

Be safe, be seen and heard!

Have you got a 5v usb step down transformer connector in the 12v socket?

Hello friends, it was a battery error. I installed a new one and it wasn't 100% fully charged. As a result, she lost her tension again and again. Now everything works fine. Thanks for your tips and hints....
Greetings Kismet