my bmw k100lt wont keep the battery charged and after about 30mins it dies ,when itry to restart it the battery is already dead ,i thought it was the alternator so i took it off ,went to check it and it was fine so im thinking it is the battery although i bought it about a year ago but its being sitted off for about 6 months ,so what can it be ,should i replace the battery again?

cdm, October 2009

plates are probably sulphated,but have you metered your circuit? corroded connectors can cause all sorts of problems

Velofellow, October 2009

Your BMW dealer or any bikeshop should be able to test your battery to see if its toast.
You can also check that the reg/rec is ok by putting a multimeter across the battery terminals, you should be getting a reading of between 14 & 15 volts while the engine is running.
It does sound as if you need a new battery especially if it has been lying up for 6 mths without getting a regular charge. Chances are the cells have probably sulphated & now it won't hold a charge,
regards Stephen.

steo, October 2009