HOW-TO Replace Battery on A Polaris Sportsman 550 EFI ATV 4-wheeler Today, I am replacing our 4-wheeler battery. She sat around in our storage unit for a while till the battery finally gave out. We bought a new one and replaced the battery. We have used the 4-wheeler since then and she runs perfectly, guess I didn’t mess it up, LOL! It was actually really easy to do, I expected it to be harder than it was. I probably wouldn’t have been able to work my way around it if it wasn’t for dad telling me how to do it along the way. I’m so glad the 4-wheeler is working again.