This has been a lifesaver!

I live in Northern Ontario and it gets VERY cold here in the winter. I use this to jump start my battery when it hits -40. It is now about 6 years old and doesn't hold a charge as long as it used to but it still gets the battery running and I can use in more than once between charges. I have the 700v and it works just fine.

This is a lifesaver if you don't have booster cables because you just plug it into your car and let it charge your battery from the inside. It only takes 15 minutes. Just make sure to always have it charged and ready. It also works as a flashlight. Can be found at Canadian Tire.