I have a 2008 Kawasaki bruteforce 650 4x4i. But I went to start it and it wont start. I hit the start button and it makes the noise to turn on but it wont turn on, then my battery starts going down, I put the charger on it and it gets charged and try it again and at first when its cranking yeah sounds really strong but then after a few times it just gets weaker and weaker. What could it be how can I start eliminating potential points of problem, could it be a battery, that's what I'm thinking but how can I confirm, cause I charge it and check the voltage and its almost 13volts then I hit the start button volts drop to 10. something as soon as I let it go they go 12 something and after that they just keep dropping. Any ideas on what it could be.