Replace battery or not?

[heathenbrewing]

If the crank is slower, would you consider this more of an indication of a dying battery over the technical checks?

So the past 2 weeks the starter has cranked slower than it did previously. Car still starts but I thought I should look into a new battery. Pulled out my owners manual and it states a reading of 12.8 - 12.9V the battery is considered charged. So I drive to the store to look at batteries and after 20 minutes I go outside to check the voltage (as per manual) and is bouncing between 12.9 and 13. Decided against the new battery since I left the tools at home. Check the V again and it was at 12.9. This morning it was again 12.9. Btw, the eye indicates the battery is good.

Battery is 6 years old
Operated in a year round warm climate
Manual states any voltage below 12.6 = replace battery

 

[DBMaster]

It's certainly old enough to be worn out. Voltage won't tell you everything, such as how much of a load it can handle. Any store that sells batteries can wheel out a tester and test it for you free. I would do that. when it goes bad you'll get slow cranking for a short while and then no crank. The only battery I ever had that gave me more than a week or two of warning was an Optima red top (AGM battery).

 

[scurvy]

Originally Posted By: heathenbrewing
So the past 2 weeks the starter has cranked slower than it did previously.
...
Battery is 6 years old
...


Those alone are enough for me to condemn a battery for replacement.

 

[wrcsixeight]

An aging battery is like a gas tank which keeps getting smaller.

You can still fill it up, 12.9v, but it only takes a 'gallon' to do so, and you need 3/4 a 'gallon' to start it.

6 years is a respectable lifespan for a battery. If you want to drag it out longer, carry jumper cables.

The manual stating 12.6v or less = replace is one of the more ridiculous things I have read.

 

[SwampSurvivor]

Batteries aren't good for more than 4 anymore

 

[Charlie1935]

Get the battery load tested and the starter checked for amperage draw.

 

[NateDN10]

Originally Posted By: Miller88
Batteries aren't good for more than 4 anymore

The battery in my Cobalt is 7 years old with no signs of dying. That it's trunk-mounted certainly helps.

 

[heathenbrewing]

Thanks all. I guess I am just trying to avoid dropping the change if I dont have to, but I guess 6 years is a good run woth an OEM battery.

I think I will take it to have it load tested.

 

[heathenbrewing]

Originally Posted By: wrcsixeight

The manual stating 12.6v or less = replace is one of the more ridiculous things I have read.


Maybe it was discharged not replace. I left the manual in the car.

 

[440Magnum]

Originally Posted By: scurvy
Originally Posted By: heathenbrewing
So the past 2 weeks the starter has cranked slower than it did previously.
...
Battery is 6 years old
...


Those alone are enough for me to condemn a battery for replacement.


I pretty much agree, although slow cranking can also be due to the starter getting older and its grease and oil getting thicker in cold weather. Some parts stores will load test a battery for you, and that is the real kicker. It may read a perfectly normal voltage with no load, but sag way more than it should when it has a load drawing current from it. The internal resistance of batteries tends to go up as they age, so their output voltage sags under load worse and worse.

That said, most conventional car batteries I've had in the last 15+ years have worked GREAT right up until that time when they won't do ANYTHING anymore. AGMs are different- they tend to die more slowly like conventional batteries used to. At least that's been my experience.

 

[HerrStig]

Have it load tested. Hot weather is tough on batteries, the summer may be catching up with it.

 

[JHZR2]

12.9 is over fully charged, it is holding a surface charge. Good news is that self discharge isnt crazy high if it is holding it, and there arent funky car parasitic loads either.

My guess is that the impedance has grown to the point where under load, the voltage drops quite a bit and the battery is struggling. Remember that Vt=Voc-IR.

This is why though I hate HF for the most part, I like their cen-tech digital battery tester - because it actually tells you the impedance of the battery.

You could use a carbon pile load tester too...

 

[Dave Sherman]

I changed my battery last winter because it was cranking noticeably slower than before when it got down to 20 degrees or below. I thought 4 years was a little young, but it failed a load test. On the other hand, I got 7 years out of my Saturn's factory battery before one fine day it went from fully functional to nearly dead over a couple hours. If it's cranking slow and it's not a fault of the starter or loose/dirty battery cables, change it before it leaves you stranded.

 

[4x4chevydude]

You could test it alot and get good readings but performance tells more....at 6 years old I would replace it now but since your climate doesnt get bitter cold then maybe just leave it. I replace old batteries before winter here since it drops to -temps in the winter but if it didnt I might leave it.

 

[Chris142]

Originally Posted By: Miller88
Batteries aren't good for more than 4 anymore

that has not been my experiance. my last battery out lasted the 84 month warranty. my bosses wife's 03 is still running the original battery

 

[JamesBond]

Have you taken the caps off and checked the electrolyte levels?

And not to be a pessimist, but I have a feeling if you take your car to a parts store to have the battery checked they will always tell you that you should replace it. So maybe take the diagnosis with a grain of salt.

In my car, I keep jumper cables in the trunk, In my parents, gf, grandparents cars the battery gets replaced.

 

[SwampSurvivor]

Originally Posted By: Chris142
Originally Posted By: Miller88
Batteries aren't good for more than 4 anymore

that has not been my experiance. my last battery out lasted the 84 month warranty. my bosses wife's 03 is still running the original battery


Different climates. Where I am, -20F a few times during the winter is no uncommon. A few years of extreme temperature changes are not good for vehicles.

 

[DBMaster]

I guess there are always qualifiers. In Texas, with a battery mounted in a hot spot under the hood, you are lucky if you get more than three years out of a conventional battery. I had a number of brands in my 89 Accord and none lasted longer than that in 23 years. An Optima red top lasted six years. That is what you would call anecdotal evidence. If ever in doubt, get a free load test and alternator test at an auto parts place, Sam's, Sears, NTB, etc. and find out.

 

[Volvohead]

Originally Posted By: HerrStig
Have it load tested. Hot weather is tough on batteries, the summer may be catching up with it.


Summer kills them. Winter buries them.

 

[HTSS_TR]

Try Thermo-tec heat barrier, it reduces the heat from the engine to the battery.

Amazon has several larger sizes, cut to fit your batteries.