What size battery for a 2002 chevy trailblazer?

The 2002 Chevy TrailBlazer uses a group 78 battery that has at least 740 cold cranking amps to be able to start it. The cold cranking amps is a measurement of the maximum number of amps that the battery can give off to start Your vehicle at freezing temperatures. There are two main types of batteries that are on the market these days, lead acid and AGM. Lead acid are the traditional type of battery that have wet cells that will need to have water added to them periodically. AGM is a newer type of battery that has a sealed technology and uses gel so You will never have to service them. AGM batteries last longer and give better performance than a lead acid, but they also usually cost more.