School me on a new starting battery for my TJ

A little update - new red top Optima installed 10/24/2024

Just a little over a year now and started having some problems.

A couple weeks ago it was a slow/ almost no crank over.  This was after sitting for over a week and right after a single digit temperature night.

Charged it up and ran fine the few times I used it. 

Tuesday, I went to start and it was the same thing again (Started and just drove it Sunday)

Charged it.

Left it off the charger last night and this morning when I checked, it was at 11.8V (15 degrees out).

So I disconnected it to remove it.  Just went out (a couple hours later) and it's back up to 12.01v.

I don't think there's too much of a vampire draw on a TJ?

I don't think there's a warranty with Optima since it's over a year old (battery date is 9/24)

Maybe Autozone has a warranty...

Optima%20Red%20Top%20Battery%20Dec%202025-M.jpg
 
Thanks for the info about the possible warranty.  pretty sure I bought it at AutoZone.

Funny part is I have the original Optima that came with the Jeep sitting out in the barn for years and it holds at around 12.6v whenever I check it.  I only top it off twice a year when I use it to power my hoist to take my hard top off & on, rest of the time off the charger - it holds it's voltage.

The new batteries aren't like the old one (that one is from 2004!)
 
It just started up fine even though it only got up to 12.04v as it got warmer out (just sitting, no charger).

Tomorrow I'll throw the load tester on it and see where it's at for CCA and internal resistance.  If it shows bad, I'll get the warranty replacement.  The battery hold down bolt in back under the firewall ECU harness sucks to get to!

 
When I worked for advance auto many moons ago, we would warranty out as many of those optima battery’s as we sold. I have no idea if they have gotten better or not, but I vowed to never buy one.  I sell interstate at work and they are pretty good, but I second what others have said about Walmart batteries. The only thing I don’t like is having the drag the core thu the store, or dealing with someone who hardly knows what a battery is in the event of a warranty.
 
The last battery I put in the Beetle was an 850CCA AGM, It was the first battery over 600CCA I have found that would fit. It made a huge difference starting in the cold.  I noticed that over months the residual voltage would drop.  One of the single digit mornings we had this year the Beetle wouldn't start.

I have a trickle charger that has an AGM/Lead setting. I put it on AGM and charged the battery over night.  The car started fine the next day.

The residual voltage went back up to normal and seems to be staying there even in the cold weather. 

Do you think it's possible the alternator is not fully charging the AGM?  The voltage goes up by a couple volts when the engine is running so the alternator is putting out.

What's the difference between charging with the AGM/Lead setting on the charger.
 
I think the last couple of batteries I got were made by Johnson Controls.  I know one time I was having a slow start issue (that turned out to be a starter) and I brought a year old battery back to the store and they swapped it out for a new one, no questions asked.  Not sure which store, but it was one of the major auto places.  I tend to buy middle of the road batteries price wise.  The Jeep sits a lot during the winter.  I'm not sure what's in it right now battery wise, but last week I put the charger on it and was surprised that it didn't take longer to change from charge to maintain.
 
King of the Hill said:
What's the difference between charging with the AGM/Lead setting on the charger.

I'm pretty sure the AGM settings are a slightly higher voltage and lower amps.  My noco charger has a setting AGM/Cold.  AGMs need between 13.8-14.6 volts.  I read some trucks (like tacomas/4runners) alternators only put out 13.5v running so the yota guys put in a gadget that tricks the computer to raise the charging voltage for AGM.  Charging under 13.8 causes capacity loss on an AGM and will ruin them.
 
If I can find a 1000CCA battery I will use it when ever possible.  A friend of mine had a built 396 Chevelle that I had never heard run.  One day while I was down there he was going to fire it up, I don't know how long it had been sitting but when he hit the key all you heard was the starter ring like a bell.  He said the problem was the battery and I was skeptical.  He said he forgot that he put his good battery in a car he just sold to his buddy.  His buddy came over with the car and he took out a 1000CCA battery and put it in the Chevelle.  When he hit the key it spun right over and started right up.  I couldn't believe how much the big battery made a difference.
 
So  after I charged it up Friday, I let it sit (still in the Jeep)  Battery dropped to 11.9v by this morning (15 degrees out)

I probably have a slow draw to figure out!

Ran the Jeep for a few minutes and then tested the battery. 

Tester says "good" but what do the numbers mean?  I kind of understand CCA and 626 is definitely lower than the 800 CCA listed on the battery, but what does the internal resistance mean in our use case?  Is 3.95 milliohms bad or good?  When I looked up the subject, all I got was resistance to charge/discharge rates regarding to solar or competition audio uses.

Current%20Optima%20Test%2015%20degrees-XL.jpg


for reference I checked the 20 year old Optima in my barn (sticker shows a date of 2004).  I expected it to be worse than it is...

Old%20Oprima%20Battery%2015%20degrees-XL.jpg



 
I wonder if the CCA would go up if it's fully charged?

AI Says:

Based on the readings shown on the Topdon BT100 tester, the battery is in fair health and a good state of charge, but is showing some signs of aging. The tester itself indicates "GOOD BATTERY".
Analysis of Readings
Reading Value Analysis
Health 61% This indicates the battery has 61% of its original capacity. The typical industry standard for replacement is when health drops below 80%, with most experts agreeing replacement is necessary below 70%. At 61%, it is nearing the end of its useful life, especially in cold weather.
Charge 70% A voltage reading of 12.42V corresponds to approximately a 70% state of charge. A fully charged battery typically measures 12.6V or higher when resting. This indicates the battery needs to be recharged to prevent further sulfation damage.
CCA Tested 626 CCA The tester measured 626 cold cranking amps (CCA). This is compared to the rated 800 CCA.
CCA Rated 800 CCA A healthy battery should deliver at least 90% of its rated CCA, which would be 720 CCA in this case. The measured 626 CCA is below this threshold, indicating reduced performance under load.
Internal R 3.95 m? Internal resistance increases as a battery ages. While there isn't a universal "good" number for all batteries, a value of around 3-4 milliohms is common for a battery showing some wear but still functioning.
Summary
The tester has determined that the battery is technically "GOOD", as indicated by the green LED and message on the screen. However, the specific readings suggest the battery is aging and losing capacity.
It is currently undercharged and should be fully recharged as soon as possible.
While it still functions, its capacity loss (61% health, 626/800 CCA) means it may struggle to start the engine, especially in very cold temperatures.
You should monitor the battery closely and consider replacing it proactively to avoid being stranded. Would you like to know some signs that indicate it's time to replace the battery?
 
Im in need a battery for the Sequoia, it will not remote start when its been sitting over night and it cranks slow with the key.  I tested mine and well.....battery says its 725CCA.  I have 87 lol.  Not even sure how it starts.  I've had great luck with MidState battery in Bloomfield.  I get there seconds, work great just not petty.  Had one go bad and they swapped it for me.  Ill be getting one of those for the Sequoia.
 
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