I had minor starting issues in -30C weather a month ago, so when I went in for my first major service I asked them to look into it a bit. I also wanted to know if a block heater retrofit was possible; answer, not really since the block heater is installed in the water pump. Anyway, after a very long wait to recharge the battery they declared it a pass; 12.44 V and 383 Amps compared to a normal battery voltage of 12.8, and rated 420 Amps. I was startled to learn the battery was down so much. A week prior I had spent 20 hours (in 2 days) on the road, so it had ample time to fully charge the battery.
I have determined that my Atlas has the EFB (Enhanced Flooded Battery). I believe the alternative battery is the AGM. From what I have read, the battery type needs to be entered into the car computer so that the charging system knows the correct charging voltage to apply. I checked out the battery again a couple of days ago, and before starting it was down to about 12.1V, and upon starting was getting 15.0V at idle. Since normal battery voltage is about 12.8V when fully charged, in good condition and with the surface charge drained off I believe the battery to be in marginal condition at best. Also, the charging voltage seems to be a little high since a max of 14.8 at mid RPMs is typical. But I understand that the AGM needs a higher voltage; perhaps 15.6V.
So, it does seem important to correctly identify the battery in the car's computer. But if the information is not correct then I can foresee problems; overcharging a EFB on AGM setting and undercharging an AGM at EFB setting. I had get the correct info on the battery to set the correct mode on my new battery charger NOCO G7200. I think that makes six so far, but the only one that can safely be used on some of the new batteries.