I drove Canadian & Alaskan arctic in the summer not the winter but one battery was more than enough for my KJ CRD http://drivingtothearctic.blogspot.com/
In winter a reserve jump battery might be useful. I used to carry one in Death Valley & other off road runs with my XJ but that was a ratty old vehicle. In the arctic winter it is important to include block heater and that far north some folks have a heater for their battery.

FYI: It is NOT Canadian law LOL.

Also, Why not just a booster pack instead that you can use for multiple purposes.

Canada does have a summer too. Best to go then. Unless you are planning on taking the Ice Highway?

Take lots of pictures and don't forget to look for underwater elk!

Man, don't think you're fooling anyone with that underwater elk stuff. Those elk have already gone to Greenland for the winter. It's those ferocious hitch hiking penguins that you should be on the look out for. Sure, they look cute at first but once they get in your vehicle you're done for.

I'm going to splain it one more time (I pretty much posted this more times that I can remember) before a MOD moves this to electrical...

All power to operate a vehicle comes from the alternator (all power to move a speaker does also). Once the Batt provides juice to start a vehicle it immediately becomes a load on the alternator as does the electrical system and any accessories. If you add another battery, you add an additional load and since the alternator can't generate "more power", it's output is now split again and everyones share is reduced (like a Fed program).

Keep in mind that an isolator system isn't perfect either. There is loss through the isolator itself (reducing the charge voltage) and since the "extra" battery is still connected to the circuit via the chassis (negative return for the whole electrical system) it can still discharge if the main battery discharges as well. Electrons have a nasty habit of traveling to a positive charge when there's a difference of potential. Since there's no isolator on the ground wire, and electrons seek balance you can see the potential for extra batt drainage when you least expect it.


Ohm's Law..... you betta recognize... chilly willy.