Yes , the battery could have a weak cell , and age has nothing to do with it , it will have all the voltage because its not a dead cell , which would make it have something like 8.5 volts , (approximately 2 volts per cell) , but with a weak cell , the battery would have full voltage , but under a load , the amperage drops so low its unable to pull the load required to spin the starter fast enough to start it , a automotive parts store (Autozone , etc.) or a bike shop , should have a Battery Load Tester , and it will tell immediately if the battery is at fault and can't hold the load , or on its way out due to a weak cell .....
