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· Registered
93 Posts
Hi Winston, considering the unloaded battery voltage is 12.87, for AGM that is a good charge,
the voltage collapse to 12.3 ignition on and just over 10 v cranking is borderline,
testing the battery cca performance which should be at the rated amps, with a good electronic tester,
and starter motor current draw would be first checks,
the 60 seconds is the network shutdown period and not necessarily an issue,
if it had an overnight drain you would not have the 12.87v
The boxer engine does demand a strong battery, and starter motor,

· Registered
93 Posts
Hi Winston,
when you are performing the test , do you recall how long the ignition / 10 a fuse is live total time in minutes to reach 10 v from 12.87, ,
It is possible to measure the actual current drawn by measuring the voltage across the fuse,
there is a calculation matrix depending on type of fuse, i use an amp hound when checking muliple fuse boxes to save time,
out of interest what other additional electrics are added and how are they powered/ controlled
have they been in use when the bike intermittently fails,
what journey times frequency in the days before the non start,
what battery voltage is displayed when the non start occurs without cranking ,
apologies for the questions, trying to help,

· Registered
93 Posts
Hi Winston,
Apologies i have been busy and skim read the thread,
i have had a good read and hope the below helps, ,

i am assuming you have the regular 12AH 200 cca battery, ?
from your simulation tests 5 can shut down cycles plus a little extra say 6 minutes collectively without charging, to draw from the settled charged voltage to just over 10 v,
it would be ideal to start with fully charged using an ammeter from the battery positive to the bus bar, to measure all current being drawn during your 5 cycle tests, amps , volts plus time drawn,
with accessories fitted and set as they would be for riding when the random low volts non starts occur,
measuring the exact current draw including fuel pump and exhaust flap cycles, can awake 60 second to shutdown loads etc ,
would be useful for clarity of actual current draw and remaining voltage in ready to ride mode,
the next step is to start the bike with the battery at least down to 12.4 v and measure voltage and current flow into the battery for at least 5 minutes, and then considering recent journey times decide if sufficient potential is being restored,

my reasoning is to establish how much of the battery potential is used against recovery reserve capacity as accurately as possible,
which would be before any component chasing,
yours clearly runs out of reserve capacity over a known period,

I use an inductive clamp type multimeter, its less invasive from a time to dismantle perspective, and creating un necessary fault codes
and covers a wide current range, the slight drift even for small values is marginal,

Only once the running charge time and demand is considered within capability of the battery to be acceptable,
Would i consider moving to component draw and then heavy draw tests,
Such as starter current at the heavy supply cable and voltage at cranking can help diagnose high / low current draw and focus on wiring and starter performance,
good luck,

· Registered
93 Posts
Hi Winston,
if i were to consider the amp hound and its useful but limited function on circuit loads ,
an inductive amp clamp would be my first choice for general testing, and my go to for this task,
its important to quantify the current drawn,
measuring directly at the battery ,performing tests as Sizzling Badger has,
Then the current flow every thing off with no load ideally no more than 0.05a,
then charging current being absorbed into the battery, it should climb to a peak and settle down to approx 20% of the rated ah capacity , t which could be tested after a journey to avoid overheating if necessary,
The alternator max output is just over 55a,
bearing in mind the oe battery is 12 ah there is not much reserve power to play with,
its well known the battery needs to be 100% , mainly due to the old school car type high current draw starter motor , and the big old engine running gloopy 15w50 oil,
as the issue has not occured since your testing simulations and support charging, the above should help find why the battery is running out of reserve power,
see attached, this is my multimeter that i use before, amp hound, thermal mapping and scope,
good luck, forest
Liquid Fluid Bottle cap Measuring instrument Flooring
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