How many batteries does your U bass have? Is you Yamaha active, and if so, it would not use more than 2 batteries a year, unless it is 18v and requires 2 batteries, than you would not use more than 4 year. The Ray5 will use 2 per year max (if you like and keep it). I would say keep them in the refridgerator or a good storing placy, you got 2-3 years supply 