Battery Optima vs Costco?

[petaling]

In my cold environment,a Costco Group 41 (650 Cold cranking amp) and 2 previous ACDELCO batteries with the wasteful alarm system/short trips only lasts 1-2 yrs.Because of the generous warranty and declining prices,I pay less and less per year to get a replacement battery.I started with the 90 C$ ACdelco 6 yrs ago now I am using the fourth battery in 6 years at 65C$.ie I got 25 C$ back after spending 90C$ 6 yrs ago and got to use the 4th battery.Not bad but too troublesome to remmeber to get battery out and haul it back before minus 20 c with windchill hits.

I.ve checked the alternator output 14V steady,at idle 14.1 or 2 at 1500 rpm,2000 rpm.Not overcharging.

I've phoned Optima,they told me while no battery fits exactly, their group 75/35 redtop is the best bet.But this is only sl more CCA,While others has said on this site Group 34 RED top is the way to go.

Thanks for any comments from colder Us climes or Canada or other cold countries!