hey scotty, i have a 1998 jeep grand Cherokee that often takes a little while to start it has always done this but now that i have moved further north in Canada have noticed that it wont start even if the block heater is plugged in, it will only start if i keep the battery on a maintainer, i had the battery tested but it tested good except the cca that the tester read was 649 while my battery is rated for 775 cca, what does this mean, it wont start when its -25 degrees Celsius or colder, what do i do?
Change the battery and find the one with the highest CCA value that fits your car.
Not to mention battery cables. That Jeep is 23 years old and at those kind of severe low temperatures any degradation of the cables is going to be a problem. A popular upgrade on Jeeps is to install heavier gauge battery cables to reduce voltage drop.