Date On Deep Cycle Batteries. Shelf Life?

tracker01 · October 15, 2011

I visited my local Cabela's yesterday to look at their "AGM" deep cycle batteries for my trolling motor. There is a number stamped into the top corner of the casing and I have to believe it is the date of manufacture. They had eight AGM batteries in Group 24 and all had the numbers 04-01-10 stamped on them. Does that mean that these batteries are at least a year and a half old? Is this a good thing? The clerk went back into the warehouse and said he found a few with 11-01-10 stamped on them. That's still almost a year old. Is there a rule of thumb on shelf life for deep cycle batteries? Does that rule change for regular (add water) batteries verses sealed AGM batteries? What is the oldest date you would except, paying full price on a new battery?

Jig Man · October 15, 2011

I don't know about the number. What I would be concerned with is the warranty period. It should start when you put them into service. I recently switched to agms and decided to pay a bit more and go for more warranty so I bought Optimas at Auto Zone with a 3 year warranty.

Way2slow · October 15, 2011

Most top brands use 12 months as their shelf life

The date you are seeing is most likly the date it was delivered by the warehouse, not the manufactoring date. That is usually hidden in a string of numbers and letters around the edge and you need the manufactors code to determine it.

If the sticker (like Wal-Mart) and many other use, or the date stamped in it like your's, is more than a few months old, don't buy it, make them check stock for a newer date. Batteries self discharge on the shelf just like they do in you boat and should be toped off every month or so. That does not happen once they are delivered and a lot of the wearhouse don't do it either so it may have been months since it has seen a charger. Therefor, you are buying a brand new battery that could already be significantly sulphated. It will test withing specs, but nothing near what it would when new. They over build them to allow for this so they will have a shelf life, but who wants a battery that's only 75% of what it was when new, I don't. For instance, a 550CCA battery can test at 500CCA and still be sold to you as a good new battery because it's within tolerance, but before it sat on the shelf for months, it may have tested and 780CCA.

I will never buy a battery that's several months old. Well, I only buy from the distributor and are friends, so I don't have to worry about that so let me say "you" should never buy one several months old.

Never buy from a small retailer like you're small volume boat dealers, marina's etc. Only buy from high volume retailers than have the capability to keep their stock rotated.

One additional note, be leary of stickers. Some not so honest wearhouses will pick a battery up from one place because it's been sitting there a long time and stock it in another location, pulling the date sticker off that's several months old and putting a current one on and that retailer would never know the difference. I have been in one of the import wearhouses and seen them doing this several times.

by the way, I haven't check in a while but most manufactors would give you the date code. Some use to have it on their websites.