What is the impact of long-term storage on sealed lead acid batteries?

[I_am_learning]

I am offered Sealed Lead acid batteries at heavy discount (half the price) at local Sale. But they were manufactured some 5 years back.
How much damage does long storage do to them?
They have never been touched. Just bought 5 years back, and stored.

 

[uart]

Be careful, if they've been allowed to go flat then they may be good for nothing but scrap metal. When lead acid batteries are allowed to sit in a discharged state the electrodes "sulphate up" and they're rarely of much good for anything afterwards.

If however they've retained more than about 30% charge (or have had a trickle charge every now and then) then they could be in good condition. Without any more details it could be a bit of a lottery.

 

[yungman]

That is good info, I have no idea.

 

[I_am_learning]

Be careful, if they've been allowed to go flat then they may be good for nothing but scrap metal. When lead acid batteries are allowed to sit in a discharged state the electrodes "sulphate up" and they're rarely of much good for anything afterwards.

If however they've retained more than about 30% charge (or have had a trickle charge every now and then) then they could be in good condition. Without any more details it could be a bit of a lottery.

They are still in their seal. Never Touched, so never trickle charged or anything.
Assuming, initially fully charged at manufacture and most optimistic self-Discharge of 3% per month, the charge left after 5 years is 0.97^(5*12) = 0.16 = 16%.
Because the battery were stored in not so good temperature, it should have much lower charge than that.
(But do self-Discharge rate remain the same or they acceleratre/deccelerate?)

Anyway, I now think they aren't the best bet.
But, I have heard somewhere that you can recover from sulphation by heavy bench charging or the like.

Also, the sale has been open for an year now, and rumor has been around that those who purchased the battery at the beginning are pretty happy with it till now. However I doubt that they don't have enough knowledge to decide whether the battery works as per its nameplate rating.
Actually they are selling at 1/3 rd the market price.

 

[yungman]

Well the non electronics side is whether you have any need of one? Can you find one that fit into your car? If not, I won't get it. You are looking at the price, but if you don't have particular immediately use of it, it will be sitting for another few years and you'll be selling it at 10 years old and that would be bad!

Don't just look at the price that you cannot refuse. AND this is not from knowledge of electronics....This is learned from my wife and my own mistake. I used to love Smucker's orange and Strawberry preserve. Two years ago they had a big sale for $2 each and was a very very good price. I bought like 30 of each. I ate, and I ate and I ate...and ate! Till the point I was so sick and tired of them! I still have like 25 bottles, they just pass the expiration date! Only stock up on stuffs that has no expiration date.

The lesson learned is only get what you need plus one if you have use of it.