I've noticed lots of the stores that sell batteries have them on the shelf a lot longer than a yr. or more, How much does a flooded battery degrade over a period of time before it is considered no go for use anyone ..I've gotten different answer from different people ,,could someone explain, thanks
I'm not an expert on these but I've looked at that same question. I think that the best answer (as in most things complicated) is "It Depends ..."
Basically, if the retailer is careful (a full charge and a good check with a load tester when he receives the battery or -- if the battery was delivered "dry", when he adds acid), then a complete re-charge and short float at intervals while it's on his shelf), then a battery will come off his shelf in good condition, even after a few months.
There are two issues with this -- the first is that most retailers aren't that careful. The second is that even if a battery is kept charged on the shelf, it's life is partly taken up by those months on the shelf.
You might think of battery life like this -- there are three conditions:
1) Perfect battery maintenance -- When the battery is new, it's given a careful, correct acid fill and is given the best "break-in" conditioning charge. Then it is immediately put into a vehicle and the vehicle owner gives the battery good maintenance (keeping it charged, keeping water levels correct, doing an equalize cycle when needed, protecting it from temperature extremes when not in use, etc.) Let's say that under these "perfect" conditions, a battery will last for 8 years.
2) Perfect battery maintenance, with some shelf time -- this would be like #1 but with storage (under excellently-maintained conditions) of a year on a shelf. Under these conditions, you could still expect a long service life but the battery would probably only last 7 years in the vehicle.
3) Not very good maintenance in storage -- this would be for a battery that's not well set up when it is put in storage and is allowed to sit there partially discharged and unmaintained for a while. It may "look good" - good sitting battery voltage, apparently taking and holding a charge well, etc. -- but if "sitting damage" or sulfation has taken place, the battery may only last 3-4-5 years in service, even if the owner maintains it well once it is in the vehicle.
So, to be sure of the absolutely best battery service, you want a battery that is well setup when new and doesn't sit on a shelf. Some owners will only accept a battery that is setup and serviced at the time of sale (i.e. no shelf time). Others will accept a short time 2-3 months, if the know that the battery was correctly set up at the time that it was put on the shelf.
There's no exact
answer, but I think that you can see that the time and effort (which translates into money that the retailer will have to put into the battery) of conditioning the battery when new, and the time that it spends on the shelf both make a difference. Be sure that you know how knowledgeable and thorough your retailer is, then make your decision on how much shelf life you will accept.
(Mostly here I'm thinking of wet-cell batteries - similar but different factors may apply to different types of batteries. There's a lot of judgment needed for individual circumstances.)
HTH, BH NC USA