We get a lot of calls with regards to bike batteries, especially Harley-Davidson batteries. People keep calling and asking why their bikes engines are not turning over. They mention they haven’t ridden the bikes in a while but have started the motorcycle twice a week and kept it idling for a few minutes, so why is it that their batteries have all of a sudden become weak?
Fact: the starter motor on a motorcycle takes a fairly high voltage to actually crank and turn over the engine which means every time a bike is started there is a massive drain on the motorcycle battery.
Based on the above fact it is a bad idea to just start the bike and leave it on idle and hope that the battery is charging and will be in good condition. It is however a good idea to run the motorcycle for at least 100Km once a week on a continuous stretch so that the battery gets properly charged and at the same time one would be able to make sure that the bike is running properly.
Another good option to keep the battery in good condition would be to keep the battery on a trickle charger at least once in two weeks if you cannot take your motorcycle out regularly in order to keep your battery in good health.