Do you absolutely need one, no. Good idea, yes. I use a CTEK unit that is mounted on the work bench next to the bike. A plug is hooked up to the battery. Every time I park the bike, I plug it in. You'll get mixed reviews. Check out their site and others to learn the benefits. For me, I leave the battery in the bike all winter plugged in. That was the main reason I purchased a charger. One of the auto shows I watch sold me on CTEK.