Can a battery test "good," start the truck reliably every time, but actually have a depleted reserve capacity?

Last week, I was working on the truck, and had the key on (run position) for about 30 minutes. (Fan, lights, radio, etc. were turned off.) After this, the battery was low enough it could not start the truck.

After charging it overnight, I was buying some stuff at Autozone, and had them test the battery. Battery read "100% charged, good battery." The next day, after starting once and driving about 20 minutes, I decided to try Advance Auto, and see their result. "Good battery, recharge."

Battery voltage this AM (after driving most of the day yesterday) is 12.07 VDC. Headlights on low-beam drops this to 11.75 V. Charging voltage is 14.7 volts.

I'm wondering about the the real capability of these hand-held battery testers the stores use. In my memory, the old "wheel-it-out-to-the-vehicle" units seemed to run the battery through a series of tests that took about 2 minutes, and drew some serious current. The AZ and AA tests took only seconds. What are they really testing?

I've not yet pulled the cover off the battery to see if it may be the original (it's possible). If so, a new one will go in regardless, but this is a weird one.

Andy

 

The stores testers are junk.....

Turn the head lights on, and have someone start the car as you are testing the voltage at the battery. If it drops quite a bit, especially below 12 the battery is junk.

 

When my battery died last summer it tested "good" after I got jumped and drove to autozone yet it wouldn't start the truck. It only started to read bad after I triedto start it hooked up to the tester. I knew I needed a new battery but they still felt the need to test it and tell me it was fine regardless if it started the trick right in front of them or not.

 

If you have 12.07 V after driving during the daylight, your battery is not holding a charge anymore.

Easy test at home if you have a meter and trickle charger.

Charge the battery overnight, remove it and check the voltage. If it is not in the 12.8x to 13.x range, it is not taking a charge.

Let it rest for 4 hours, and test it again, with nothing on the battery, it should be within 0.5 V of the post charge voltage ( again this would be going from 13.1 to 12.6, not 12.5 to 12.0 ). If the battery with nothing on it cannot hold the charge, it is bad.

The hand held battery tester should be able to do the same tests as the old wheeled battery load testers, but the question is can the AA or AZ employee actually use the hand held tester correctly ?
This is what I find, the counter guys at AA or AZ know LED lights, and neon underbody kits, nothing about actual car testing and parts. Aside from that, they say some of the stupidest things I have ever heard.

If you have a Napa near by, they would be able to test the battery for you in the back, and should be good at running a load test on the battery.

With summer coming up, your battery is going to leave you stranded soon, a marginal battery will flake quicker in heat than cold.

 

A new battery doesn't cost all that much. I look at it as insurance to keep from getting stranded.

 

And since you will need a new battery...

May I suggest Sears Platinum Batteries manufactured by Odyssey.

 

Well, any battery is going to drop voltage under FATHERFORD's test. It will definitely drop below 12VDC, since that's where it's starting out.

I just investigated, and the "old" battery is a NAPA 65-month battery with a DEC05 date code. Starting voltage under the conditions you described dropped to about 10V momentarily (it doesn't take long to start the thing). Since it's working on 5 years old, I installed the new 850CCA "Energizer" (Johnson Controls) battery. Testing as above yielded the same results. Maybe I'm throwing away a few more months of useful life, and under normal conditions, I'd probably just wait until winter to change it out; however, since we'll be towing the trailer around camping this summer, I'll feel better with the new one.

Andy

EDIT: I just saw all the other responses. Thanks for those. As you see, I have changed it out. Better safe than sorry.

SSCULLY: I thought that heat did more actual damage to a battery, but the symptoms would be more evident in the cold. Maybe I'm wrong.

FATHER: I considered the DH Platinum, but just couldn't cough up the extra coin right now. I've been looking for a new job since December, and things are pretty thin.

 

SSCULLY's telling you exactly how I would "test" a battery at home. I think it's entirely possible for you to have a battery that will seem to charge, but that will not hold it.

Like most people now, I have a number of battery operated power tools. Some of the older ones use Ni-Cad batteries. As these batteries age, they seem to charge normally, and will run the tool for a useful amount of time right after being charged, but if left overnight, the battery will be "weak". I've taken several of these multi-cell batteries apart and have tested each cell individually. In all cases, one of the cells will show an almost zero voltage reading, while the others will be fine. That cell has developed an internal short that causes it to discharge when not in use. I can sometimes restore that cell by applying a brief, high voltage charge across its terminals alone. This essentially "burns" through the short (kind of like blowing a fuse) and the cell sometimes works normally for a while.

I'm sure your vehicle battery has developed a similar problem. The constant charge/discharge cycles cause the plates to become distorted and eventually, a small internal short between plates develops. About the only thing you can do when this happens is to replace the battery. (Don't try my high voltage charge trick on a lead-acid battery! Exploding batteries are NOT fun!)

- Jack

 

I've done the same thing with NiCd packs. As a matter of fact, I worked on the DustBuster just this week, but might have to tear it apart again.

Just for grins, I might charge this thing up and do some voltage tests before I take it in for the core refund. It's close to the end of it's "65 months," so I guess I shouldn't be surprised if it's failing. (You'd think they put a countdown clock inside these things sometimes.)

Andy

 

Yipes! A 5+ year old battery? I'm impressed it lasted that long.

Way back in the old days, when there were 6-volt systems, (Bluejay would know about this, since he and I are about the same age), batteries would just keep on truckin', but would get progressively weaker and weaker. You could "judge" when to replace the thing by how slowly the engine cranked. Now, they just fail "totally" - one day fine, the next, DEAD!

I'm certain it's due to the thinner plates, packed closer together, to provide more charge density, but, is this really progress?

- Jack

 

65 months based on what start date? The day you bought it? How long do you suppose it sat on the shelf before you bought it?

My son's care needed a battery and I knew it was a 24. My wife and I walked into Sam's club this past weekend and there was a skid of batteries that just arrived and had not been put on the shelf, so I thought 'fresh batteries,' and right in front was a 24. AS I stood by the skid I noticed they all had a sticker on them that read 0510. Could that mean May of 2010? I looked at the batteries on the rack those stickers looked like dates, with the oldest being 0909. I put that 0510 stickered battery in my cart and bolted that fresh battery in to his car yesterday.

Point is, that 65month battery may have sat on the shelf for 8 months before you bought it. I agree, batteries should have a born on date.

My battery did the same thing as yours was doing before I replaced it.

 

Greencrew- That sticker is a "Born on date" They must have run out of April stickers so they started putting the "5" stickers on a little early. No big deal really if it's only a few days. Quite a few manufacturers use those stickers now, so if you lose your receipt, they just go by the date sticker for warrantee replacement. Wouldn't work out too well on those batteries with the 0909 stickers. I always look for the newest date sticker when I buy, but the last several batteries have been Costco batteries and I have NEVER seen date stickers there that are even a month old.

 

Jack- i too was around when 12v batteries came out and I can attest to what you said about 6V as compared to 12V. The difference is that most of the 12V batteries don't just fail one day. It CAN happen, but rarely does. I have seen literally scores and scores of different scenarios with batteries. I have tested batteries for many many years (probably conservatively into the thousands) and I test ALL my batteries at least every couple of months. I have an OTC Pro tester (a $500.+ tester) that is what is called a "conductance tester". It is the most commonly used tester today. I only purchased this particular tester because I have always respected OTC's professional quality and they claimed that the tester was accurate something like 99.7% of the time in blind tests with different battery manufacturers. I also have a 1000 amp "Carbon Pile tester" that has been the gold standard for as long as I can remember. Interestingly, they do seem to confirm each other close to 100% of the time. (I did say CLOSE) When I test on a regular basis, I can see the battery decline over a period of time (actually as long as 1&1/2 yrs+). You know when it will only hold about 11.8-12.0V on a load test when it's fully charged, it's time to change. Interestingly, seldom will you notice any difference in the way it starts, even though the battery won't last much longer. That is the difference in 6V&12V. Lots of warning with 6, seldom any with 12. Just the nature of the (battery) beast. There is enough experience to write a book, but have no fear, I won't go there.

P.S. You are right about the difference in the thickness of the plates being the difference.

 

I guess I'll be checking the date when I buy batteries and tires. No sticker on my Interstate battery from Norther Tool.

 

I learned only a few years ago about checking the date on tires, especially slow-movers like trailer tires.

The date sticker on mine is a 1/2" round one stuck on the short side of the case. Alternately, when it's sold, the dealer is supposed to knock out the appropriate dots" on the top sticker like on your Interstate. I suppose you could punch it out to be anything you want, and they'd have to go by that. (This action is neither condoned nor endorsed.)

Andy