I (we up north) have been using those for years up here in British Columbia. We use them on ATV, boats, snowmobiles, trucks cars everything.
Where I usually see them is at hunting camps , lake cabins where the trucks and ATV's sit for a long period of time and not starting.
Don't much use them in the winter as the snow covers the windshield by a couple feet deep, so pack the batteries home. However a buddy with a lake cabin built a window in the roof of his shed facing south and it is close to the edge of the roof, so the snow doesn't pile up.
Yup they work, up here we get them at Canadain Tire Stores.
Soup.