Why do new batteries with the same date measure

[Geo-TH,In]

Why do batteries with the same shipping date measure different voltages and cranking amps?
I went to RK Monday and bought 4 of their biggest AGM mower batteries. 3 of my core batteries were 9 years old, the other was 8. So I can't complain about the years I get form Excide AGM batteries.

I picked batteries that measured 12.71 volts and 435 cranking amps.
There were some batteries with 12.39 volts and less cranking amps.
So how can new batteries have less voltage and less cranking amps? If I'm going to pay $45 for a mower battery, I want their best. I don't want to take it home and charge it.

I'm guessing that some batteries may be older and when they ship they all get the same date on the sticker.

Do you take a voltmeter with you when you buy new batteries?

geo.

 

[rustred]

normal situation for battery's sitting on a shelf. what ever happened to the saying "charge before use"? used to be standard procedure.

 

[Geo-TH,In]

Why would I want to buy a new battery that self discharges?
George

 

[Jim.ME]

I think you will find every battery self discharges. How long it takes varies. The cleaner and drier the battery is the slower the discharge is. Something placed on top of it can be a conductor between terminals, it might be poor but it could be a conductor.

I still like to put new batteries on a charger when I can.

 

[Red Dave]

Good luck finding one that doesn't.

They all do it, some faster, some slower, but they will all self discharge over time.

 

[Billy Shafer]

ALL batteries will discharge ove time. Some faster than others.

 

[Steve@Advance]

Just a theory, when a pallet of batteries comes off the line, they are put on a quick charge just long enough to get them going.

Some get a better charge, some didn't make as good a connection, some stayed on longer...

But once in operation, given a properly working charging system, it will settle in and all will be equal.

 

[Dean]

Of course not.

There is nothing to be gained by measuring the terminal voltage of a cranking battery upon purchase.

See below.

Dean

 

[JD Dave]

Yes, worse yet, what the manufacturers don't tell us is that batteries (12V) at a voltage of about 10.5 to 11.25 are really dead and if left in this condition, it will severely shorten their life. Keeping a battery tender on them to maintain 12.6 to 13.3 volts will save a lot of money for battery replacement.

 

[John T]

George, Im sure you already know lead acid (including AGM) batteries sitting on a shelf even if in perfect conditions SELF DISCHARGE due to electrochemical reaction, and the longer they sit the more discharged they become. Im a long retired and rusty Electrical Engineer so don't take my word for it (see if different fact checkers have different responses lol) take a look at the paper below from which the quote below was taken.

TO YOUR INITIAL QUESTION "Why do batteries with the same shipping date measure different voltages and cranking amps?"

MY RESPONSE: Even with the same shipping date they may have sat on the shelf at the factory or a warehouse at different temperatures for different times (or had different manufacturer dates) PLUS received different degrees of charging at the retailer or upon manufacture A LOT OF VARIABLES could contribute to their voltage at Rural King

"Lead Acid batteries, regardless of construction chemistry all exhibit a self-discharge
characteristic that varies by storage temperature, state of health and state of charge of
the subject battery."

See the URL https://gelcoservices.com.au/docs/Lead%20Acid%20Battery%20Self-Discharge%20Paper.pdf

John T NOT a battery expert only one engineers opinion, others may differ
Battery Self Discharge Explanation

 

[Gambles]

Little known secret: The date on the battery is not necessarily the date it was manufactured. It could also be the month a delivery guy inspected it, peeled the tag off and stuck on a new one.
I once saw February 15 date on a battery. This just happened to be on February 2, 2015. Now think about it for a minute. Lets just say the battery came off the assembly line on 12:00 AM on February 1. The battery would go to the manufactures warehouse. Then on a truck. Then to a stores warehouse. Then to the store.
All in a matter of 36 hours? Nope.

 

[Ted in NE-OH]

All batteries are not equal. All a battery has to do is when charged, produce the rated CCW. Some will be overachievers and some will just meet spec.

 

[Geo-TH,In]

"There is nothing to be gained by measuring the terminal voltage of a cranking battery upon purchase."

I usually get 8 to 9 years out of these batteries. So there is nothing to be gained?
geo

 

[Jim.ME]

(quoted from post at 06:43:03 03/18/21) "There is nothing to be gained by measuring the terminal voltage of a cranking battery upon purchase."

I usually get 8 to 9 years out of these batteries. So there is nothing to be gained?
geo

My thought is the gain, if any, is still an unknown. You have no controlled comparison between those you voltage checked and those without or that you considered failing your test. What would be the results if the same person (you) ran the same number of batteries from the same shipment, you didn't check terminal voltage on, under the same conditions at the same time? That is how control studies are done, using several different people, and done several times, not just one side by one person. How the batteries are maintained after installation could affect the outcome, thus the need to have multiple controlled comparisons to determine the true gain.

 

[Geo-TH,In]

"Little known secret: The date on the battery is not necessarily the date it was manufactured."

That's what I'm thinking too. So why would anyone buy an old battery that has been sitting on a shelf and is not at full charge? To keep a battery healthy you need to maintain a full charge.
george

 

[BarnyardEngineering]

I've never seen a battery with anything more specific than the MONTH of manufacture on it, and it's just a cheesy colored sticker.

 

[Dean]

I get very good life from cranking batteries as well, and I do not take a voltmeter with me when I buy such. As previously mentioned, all so-called "storage batteries" will self discharge.

I do look at the date codes (No, I did not say that they are precise.) and select the most recent. Of course, I would not buy a cranking battery that had been setting on the shelf for many months.

That said, most folks do buy such discharged batteries when they buy a new car, truck, tractor, etc., because most such machines have been sitting on a dealer lot for months before sale, in addition to the amount of time between when the battery was manufactured and when it was installed in the machine. Worse yet, dealers, especially tractor dealers routinely start machines to move them from place to place without allowing the engine to run long enough to recharge the battery. It's been decades since I knew of any dealer who routinely charged the batteries of machines setting on the lot and it is not uncommon to find such machines with severely discharged batteries. For this reason, I nearly always insist that the dealer replace the battery with a fresh one when I purchase a machine unless the machine was recently delivered.

For the past several years I have been buying Deka batteries at my local CNH/Kubota store (the parts manager gives me a discount for being a good customer), and I simply ask him to order a new one rather than take one from stock.

I'll leave my volt meter at home.

Dean

 

[Dean]

Bingo, BY.

Dean

 

[Bob Bancroft]

And now the situation is exacerbated by all the electronics with their parasitic draw. Many ag machines set for long periods of time. My neighbors have a combine which kills batteries. Wouldn't you think they could be made so that when turned off, all draw is cut off as well?

 

[SVcummins]

Youve never seen a battery With a date Branded into it

 

[DoubleO7]

No matter how hard you pinch those pennies, your not gonna take them with you.

 

[kencombs]

Good read
https://batteryuniversity.com/learn/article/elevating_self_discharge

 

[Dusty MI]

At one time the Acid & Water was not added to the battery until it was being prepared to be used.

 

[DWF]

(quoted from post at 23:50:56 03/18/21) At one time the Acid & Water was not added to the battery until it was being prepared to be used.

I bought a battery last summer for the 4 wheeler. It was dry, but they had the mix to put in it. The guy selling it said to make sure you let it sit with the mix for at least 1/2 hour before charging, works fine.
DWF

 

[Dusty MI]

Also, At onetime the dealer stamped the date on the battery when it was sold.

 

[1948CaseVAI]

(quoted from post at 16:23:55 03/17/21) Why would I want to buy a new battery that self discharges?
George

All batteries will self-discharge given enough time.

George have you ever considered having a Facebook account?