Is There Anyway To Test The Battery To See How Much Life Is Left?

Unfortunately, there is no test to specifically determine how much 'life' is left in the battery. New batteries from the dealership have a relevant life expectancy of about 8-12 years. Whereas our battery has a relevant life expectancy of 3-5 years. If the battery is failing, the CEL will illuminate and a DTC will be stored in the vehicle's computer.