I understand that AC Delco encodes the month of manufacturing a car battery using two digits and encodes the year by one digit.

The battery I just purchased, for example, is labeled P124R, which, IIUC, means that it was made in December 2014.

I'm puzzled by this ambiguity regarding the decade of manufacture. How does a buyer rule out he's dealing with an exceptionally unscrupulous retailer who put on the market 10+ year-old stock? Just as importantly, how can a manufacturer of AC Delco's renown make the date this ambiguous? Is it, for instance, the case that a battery that has been sitting on a shelf for 11 years will be so unusable that it could not possibly be sold as a one year old battery?

  • Do you mean 2004? 2014 was last year and the battery your just purchased is only 7 months old Commented Jul 27, 2015 at 20:08
  • My battery code is P048R was it made April 2008 😩 Commented Feb 11, 2018 at 18:47
  • Because a 10 year old lead-acid battery won't hold a charge. It's like why they don't need to specify the year of manufacture on donuts. Commented Apr 24, 2020 at 6:28

3 Answers 3


NOTE: Much of your question seems to be a rant, so I will answer the last part, which seems to have gone unanswered to this point.

According to the Battery University, a typical lead acid battery will lose about 5% of its charge every month (whether this means 5% of of the total charge when completely full - ie: 5%, 10%, 15%, etc, or 5% of the remaining charge - ie: 5% of 100%, 5% of 95%, 5% of 90.25%, etc, is unclear). This means if a battery sits on the shelf too long, it will need recharged after a period of time to be fully operable in a vehicle.

That is for a battery which is stored wet (with acid in the cells). A dry battery (one without an electrolyte) will maintain on the shelf indefinitely. Once the electrolyte is placed in the cells, the process begins.

There is another factor which will make a battery go bad. According to the same website:

With usage and age, however, the flooded lead acid builds up sludge in the sediment trap, which causes a soft short when this semi-conductive substance reaches the plates.

This can cause issues when the battery gets old. I assume it happens at a slower rate while on the shelf, but will still happen over time as it becomes aged.

What this means is, a battery with acid in the cells can only sit on the shelf for so long before it must be recycled or it will not work right. Have no fear, though, lead from batteries is one of the most recycled things we humans pull out of the ground. A battery which has sat on the shelf for too long, while it may not provide you good usage, will still be able to be exchanged for a new one under the normal battery warranty programs. I'm sure batteries are sold beyond their expiration dates, but they are also easily replaced.

  • I really couldn't care less whether a new replacement battery is fully charged—just so long as it has enough to get me going. My question is: If you bought a battery that was made in 1990, fully charged it, then installed it in your vehicle, would it function just as a new battery?
    – Calaf
    Commented Jul 28, 2015 at 1:53
  • Not if it was put on the shelf wet, no it would not. If it was stored dry, then electrolyte added, yes. Commented Jul 28, 2015 at 2:23

AC Delco's website addresses this:

How do I read the warranty date code on my battery?

The warranty date code is located on the top label of the battery. The first character is either a P or S. The next two digits determine the month, the third digit is year and the fourth digit indicates the manufacturing plant. For example, P 094N means the battery was made in September 2014. (http://www.acdelco.com/content/dam/ACDelco/North-America/ACDelco/nscwebsite/en/Home/Auto_Repair/Battery_pdf/ACDelco-battery-warranty-information.pdf)

See the answer below for more information about battery life. Either way, the warranty period for your battery starts from the time of purchase.

  • 1
    Indeed my warranty starts from the date of purchase, not from the date of manufacture. The question then is this: Do I care when the battery was manufactured? Does it matter whether it was made in '04 or '14?
    – Calaf
    Commented Jul 28, 2015 at 1:54

It pays to get a Solar brand battery tester which uses a conductance test to evaluate how many CCA is left in your battery. That way you can decide when it is time to let go of the battery.

  • This does not attempt to answer the question in any way. The OP asked how old the battery is, not how much life is left in it
    – Nick C
    Commented Jul 31, 2015 at 8:22
  • You have to look beyond what the OP is asking. Why is he asking what he is asking? Is it wrong to address that?
    – David Xu
    Commented Jul 31, 2015 at 9:57
  • Generally, sure - but in this case he specifically says why he is asking - it's because he wants to be sure the new battery he bought is actually new, and not a 10 year old one being sold as new
    – Nick C
    Commented Jul 31, 2015 at 10:32

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