I use trickle chargers on my motorcycle and Friday car and work great. They usually come with two ways to connect. I usually use the quick connect that comes with it that way instead of jacking with the battery every time I just pull the quick connect cable out of the battery box and plug in. I usually use the cheap ones from walleyworld $20-$30 but noticed they only last about two years and stop working so you have to check them periodically if your hooked up for extended periods.
I use Battery Tender for my quad battery. It's works great... My buddy also bought a quad at the same time I did, I got the tender he didn't. He had to purchase new battery already... mine still says fully charged.