Hi all

I'm facing an issue with my XT660Z 2015 (ABS) bike, it seems like the battery are slowly (faster than normal) are drained.

During this winter I have monitored it and made frequently measurements of the battery voltage (bike has been unused, stored at 13 degree Celsius, and key in state off).

With battery and all accessories (heated grips, power plug etc) attached to the bike:
Day 0: Fully charged
Day 1: 12.79V
Day 5: 12.68V
Day 15: 12.60V
Day 31: 12.44V
Day 37: 12.40V

With battery detached from everything
Day 0: Fully charged
Day 1: 12.86V
Day 5: 12.85V
Day 25: 12.76V

Attached to bike without accessories, tank removed
Day 0: Fully charged
Day 5: 12.68V
(follow the same pattern as with accessories)

I have measured the average amp usage (over 1 minute say) and it's around 0.8mA (in serie on the positive battery terminal). Of this fuse 7 (for odometer, clock and immobilizer) seems to consume 0.74mA, does it sound reasonable?

The battery is not original, it's a Bosch M6 011 (12V, 8Ah, TTZ10S-4 / TTZ10S-BS), but it should be 6 months old and what I know completely drained once when I received the bike (could not be started then, just some relay clicking).

Googling a bit and I found a figure that at 12.5V the battery should be about 75% charged, I reach 12.5V after about 25 days, with some math this gives:

(8Ah*0.25)/25/24 = 3.333mA

And this is more than 4 times what I could measured!!

I have checked the battery with ctek:s battery tester (quick puls check I think) and also an old school thing where 100A are consumed during 10 seconds and I read of the voltage. In both cases it tells me that the battery are ok.

Also read a lot of issues with the voltage rectifier connector, I pulled out the connector and measured average amp usage but didn't have any affect.

I normally using a ctek eyelet battery indicator and after 4 days it use to tell me that I need to change my battery and after a month it starts to shine red telling me that now I really need to charge the battery. I could also say that I tried to start the bike at 12.4V and it worked.

I will try to make a measurement with fuse 7 pulled out over 5 days to see if that makes the issue go away but other than this I'm out of ideas. I do not seems to get my head around what is happening, could the battery be bad anyway?

All ideas/advice are welcomed!