Ive a 2010 Honda Accord. The manual recommends a small group 51 battery (that's OEM as well) providing 500 CCA. Various websites say to upgrade to a Group 35 or 36 providing 650 CCA. In Chicago, winters get cold. Is this upgrade ok for the alternator? The bigger battery fits my tray. Any significant reason to not do this? Thanks.
There's no real downside to putting in a larger CCA battery, as long as it fits in the space provided. The starter will only use the amount of power it needs to start the vehicle, so the alternator should be able to keep up with the charging aspect of it. As with all charging systems, it takes an amount of time to recharge a battery after starting the car, so there'll be no change there. The only real difference between the two batteries you'll be able to tell is the amount of money it'll drain from your wallet when you purchase it. Other than that, there shouldn't be any issues.