If you want to take your project portable you'll need a battery pack! For beginners, we suggest alkaline batteries, such as the venerable AA or 9V cell, great for making into larger multi-battery packs, easy to find and carry plenty of charge. If you want to go rechargable to save money and avoid waste, NiMH batteries can often replace alkalines. Eventually, however you may want to upgrade to the shiniest new technology - rechargable lithium ion/polymer batteries.This guide was first published on Jul 29, 2012. It was last updated on Jul 29, 2012. This page (Overview) was last updated on May 04, 2015.