in my experience maintenance free batteries are better for the average joe, because they do not require acid filling by the reseller.The resellers do not use a good quality electrolyte, which ruins the battery.
The maintenance free ones are fine, they dont rust the car body and do not require acid top up, no amount of extra years of battery life will ever compensate for corrosion.
If you buy a maintenance free battery buy a local brand of battery and get it fully charged before installing in the car, it will be a good experience.
I have had them last more than five years and atleast 3 years (because there is no chance of missed electrolyte top up)
As for the AC delco battery, batteries will degrade in storage, if they are already filled with electrolyte (which is the case with maintenance free batteries), now look at the AC delco supply chain, someone buys its from a foreign country, ships them to karachi ,then clears them from customs and then it stays in storage until it eventually reaches the user. All of that time is reducing the life of the battery, even before it is installed in your car.
I personally use a multimeter to check the battery voltage, when i buy a new battery, if it is above 12v, the battery is not bad.
Whatever battery you use , maintenance free or lead acid, you should give it a charge before installing it in the car, not a booster charge, but a charge to full capacity.
I am using maintenance free batteries of daewoo, solite and volta over the past ten years with no bad experience.
