2014, 450 Grizzly. I used to have a second battery w/jumpers on my ATV for various reasons. Recently I bought a battery jumper unit that’s no bigger than your I-phone. Puts out 200-400 CCA and will hold it for up to six months. It also has other charging capabilities. My ATV battery puts out about 220 CCA. I recently had the opportunity to test it’s abilities on a Polaris Sportsman with a dead battery. Fired right up.

I paid a little over 100 bucks for mine from Bulldog Verizon, but I see they are available on Amazon for less than that. There is another company that sells similar units for less.
Helped me solve a concern I’ve had for some time cause I am usually by myself and probably not physically able to pull the recoil starter add on that’s available from the dealer.
Solved my problem, perhaps it can help you.
I solved the ATV pull start, but that’s not much help when I am alone.
Thanks, Tom/Idaho