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!

0.8mA is perfectly acceptable for background current drain. This would not cause your battery to drop in voltage from 12.79 to 12.4V over 25 days.

The odd thing in your case is that the voltage drop is the same with all the accessories disconnected. USB sockets are a notorious problem for draining batteries if not isolated or ignition-switched as the step-down transformer in them can consume up to 50mA even with nothing plugged in. It can't be this though as the voltage drop is the same when disconnected.

It could be explained by a failing battery though if it has suffered internal damage/sulfation to the plates, diluted/contaminated electrolyte or has a higher internal resistance than it should from being completely discharged for a period of time. The internal resistance forms a voltage divider with the load. It is only when a load is applied that internal resistance comes into play. When disconnected from the bike there is no current drain at all, so everything is fine and no, or very little voltage drop is noticed (and will test as such on a battery tester). However, as soon as it is exposed to a current drain, however tiny, the internal resistance influences battery voltage negatively. If a battery is past it's best this resistance will be higher than normal and cause the voltage to drop more rapidly, which is I think what you are seeing.

It's actually a lot more complex than this. If you're interested in the equations and the science behind it then have a read of the attached PDF.

Attached Files

lead acid batteries.pdf (211.9 KB, 16 views)

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Wasted money on a new battery and found it was the usb 12v socket .
The 12volt side is ok but the usb 5v transformer seems to slowly drain the battery .
Had the same issue on a ttr it was the 5v usb output causing a drain .

The extra power socket I have are not an USB however, regular cigarr socket, so I cant rule out the battery...

The issues continues, disconnected all fuses (fuse 1-7 + ABS fuse + main 30 Amp fuse) as well as disconnecting the 12V socket, ctek eyelet, heated grips, xenon lights and it still drop faster than if the battery would have been completely dis-attached from the bike.

I now ordered a new original battery, will arrive today or tomorrow hopefully. Need to get the bike out of the garage and get going so if the problem remains I'll have to take it after the season.

I would also look into maybe the battery internals are the culprits as pleiades mentioned since you have no external current drain other than the 0.8mA you mentioned
So are you having issues with starting uo in winter time after leaving the bike unused for 25 days? or did I miss part of the thread!

BTW which model of CTEK do you use if it is the test & charge, then forget the test part of it; it is the same as a cheap voltmeter! A waste of money. But the charger is ace

The new battery seems a lot better, no dramatic voltage loss, need to study it a bit more. The problem was not that I got stranded but more my own fear that it would happen sinceI spotted the rappid voltage drop.

Maybe I mentioned it already but the bad battery held voltage if not subject to any power drain.

The Ctek battery tester I have is this one:

https://www.amazon.com/CTEK-56-925-V.../dp/B00COPZ842