Im designing a project with a pump that Im using for watering of plants. I need to power the arduino and the pump with some kind of battery and Im thinking about a motorcycle battery. Is that a good choice or should I choose some other one?
This is the pump Im using:
Get whatever you need for the pump, and then a switching regulator to make 5V for the arduino.
check www.pololu.com, they have a bunch.
A 12v motorcycle battery is a pretty good choice. Another added benefit is that you can buy some pretty cheap solar panels to add charge to them. I'm all about renewable energy. Besides, you don't want to have to trickle-charge a fountain every couple of days. There are some solars that clip right onto the battery without any fancy wiring needed. Not to mention those batteries are portable, rechargeable, and last a MEGA long time for house-oriented electrical projects.
Be aware that vehicle batteries are typically not deep-cycle - they are designed to be kept fully charged all the time with occasional very high current drain. Deep cycle batteries are designed to be discharged all the way repeatedly and will have a much better life than typical vehicle batteries for such use - however if the battery has plenty of capacity then you won't be deep cycling it anyway... Assume the nominal capacity to decrease with age anyway.