Cheap AGM battery.

[Moab]

AGM batteries are basically closed cell car batteries that don't need water added to them. And won't leak acid if turned upside down or sideways. There are a bunch of other advantages you can look up:

https://batteryclerk.com/pages/agm-batteries-pros-and-cons

"Pros for AGM Batteries

They are spill proof. Because the acid is held in the fiberglass mats, they won't spill, even if they are broken. 

They are safe to transport and are exempt from hazardous materials restrictions.

They are vibration resistant. They were designed to withstand the constant vibration of military airplanes and helicopters.

They are shock resistant.

They can withstand colder temperatures than a typical wet cell battery. If they are frozen, even though they won't operate, they are not damaged.

They can be installed in any orientation.

They produce minimal gassing, so they can be used in less well ventilated areas.

They have a low self-discharge rate, meaning they can be stored for longer before they require a charge.
If well maintained, they last longer than SLA batteries.

They require no maintenance.

These dependable batteries are often used in marine vehicles, RVs, golf carts, wheelchairs and scooters, UPS systems and high end motorcycles where durability is required or battery orientation is an issue.

Cons for AGM Batteries

Manufacturing costs are higher, making the batteries more expensive.

They are sensitive to overcharging and high voltages, and require full charging between uses, which can make them un-suitable for some applications where returning them to a full charge is difficult.

They require a charger specifically for AGM batteries that monitors volts, amps and ambient temperatures.
Some older battery testers can't accurately test AGM batteries.

AGM batteries are well designed, reliable, and durable power sources for applications where their advantages outweigh their disadvantages."

But suffice it to say they are the best car batteries available today.

I got into them from belonging to a 4x4 forum. In my research I found that only a few manufacturers make all of them. And simply put different branding on them for various retailers. 

In my search thru these various retailers that use the best manufacturers I found this one at Oreilly Auto Parts. It's $169.99. plus they have a 10 or 5 percent discount code for online ordering. You can also save the $20 core fee. If you can return your old battery to a local O'Reilly's.

This one fits my Jeep. But you can put in your vehicle make and model to see if it or another fits your car.

https://www.oreillyauto.com/detail/c/marine-agm/marine---boat/batteries---marine---deep-cycle/deep-cycle---marine-batteries/6bf1f04ea895/super-start-marine-agm-group-size-34m-top-post-battery/ssbj/34magm 

[majorhavoc]

Agree AGM is superior to traditional lead acid battery technology.  Don't know what it is about the lowly Kia Soul, but replacement batteries (which my mechanic says I should strongly consider, with the colder weather and my existing 4 year old battery testing as "marginal" on his diagnostic equipment) are super expensive.  The cheapest compatible battery on the O'Reilly's website is $180 and that one doesn't specify it's an AGM, so I'm assuming it isn't.  The cheapest AGM for my car is $240.  Grrr.

The battery in my Honda CB500X is an AGM. But in the motorcycling world the creme-de-la creme now is lithium, which weigh a fifth of AGMs and take up about a third of the space.  They're sold with styrofoam spacers so they don't rattle around in a motorcycle's "massive" battery box.  I wonder how long before they start showing up in automotive applications? 

[EBuff75]

The battery in my Honda CB500X is an AGM. But in the motorcycling world the creme-de-law creme now is lithium, which weigh a fifth of AGMs and take up about a third of the space.  They're sold with styrofoam spacers so they don't rattle around in a motorcycles "massive" battery box.  I wonder how long before they start showing up in automotive applications? 

Probably not any time soon for car applications, just due to the price.  Looking up the group size 35 that goes in my Mazda, I can get AGM for around $240, but a lithium runs around $830-900!  And the lifespan isn't really any longer than a regular battery.  Antigravity says 4-5 years for theirs. So it's more than 3x the cost of AGM (and about 4-5x the cost of traditional lead acid), but doesn't last any longer.  Yes, there's a significant weight-savings, and the cranking amps are much higher, but in mass-market cars (they are used in a few high-end cars - Lamborghini, Porsche, BMW, etc.) I don't seem them becoming a thing unless the price drops significantly.

[NT2C]

One thing to bear in mind is that some vehicles have sensors for monitoring their battery and these have to be recalibrated with a scan tool if you're changing the type of battery.  If you don't then they can overcharge the battery, ruining it and possibly causing damage to the vehicle.  (overcharged AGM and gel batteries can vent enough acid fumes to literally eat surrounding metal)

My advice would be to Google the subject for information specific to your vehicle before making the change.  As cars get smarter they are becoming able to sense the type of battery installed and adjust the alternator's charging rate accordingly, but it's still a good idea to check it with a scanner.

[NT2C]

Let me just add, your Jeep, Moab, is old enough that you shouldn't have a problem with any sensors but, like my '97 Dakota, it came with a regular flooded acid battery and charging system built specifically for that kind of battery. Under certain conditions, these kinds of changing systems will kill an AGM by overcharging it.  The most common situation is where something gets left on, the battery goes dead and you get a jump to start the vehicle then let the alternator charge it.  What will happen is the system will charge it at too high a voltage and current, fine for a flooded lead-acid battery, death for an AGM.  Anytime the battery becomes run down to the point it won't crank then it should be recharged with a dedicated AGM or gel cell charger.

[EBuff75]

Let me just add, your Jeep, Moab, is old enough that you shouldn't have a problem with any sensors but, like my '97 Dakota, it came with a regular flooded acid battery and charging system built specifically for that kind of battery. Under certain conditions, these kinds of changing systems will kill an AGM by overcharging it.  The most common situation is where something gets left on, the battery goes dead and you get a jump to start the vehicle then let the alternator charge it.  What will happen is the system will charge it at too high a voltage and current, fine for a flooded lead-acid battery, death for an AGM.  Anytime the battery becomes run down to the point it won't crank then it should be recharged with a dedicated AGM or gel cell charger.

When I bought another battery charger / tender, I found that battery type flexibility was one of the things which has now become fairly common.  In some cases, the chargers are even smart enough to detect the battery type on their own.  My NOCO Genius 2 (which was only $50) can handle flooded, AGM, and Lithium, plus 6V.  The lithium setting is likely for golf carts or RV house batteries more than 12v car batteries, but it's nice to have the option.

[NT2C]

Let me just add, your Jeep, Moab, is old enough that you shouldn't have a problem with any sensors but, like my '97 Dakota, it came with a regular flooded acid battery and charging system built specifically for that kind of battery. Under certain conditions, these kinds of changing systems will kill an AGM by overcharging it.  The most common situation is where something gets left on, the battery goes dead and you get a jump to start the vehicle then let the alternator charge it.  What will happen is the system will charge it at too high a voltage and current, fine for a flooded lead-acid battery, death for an AGM.  Anytime the battery becomes run down to the point it won't crank then it should be recharged with a dedicated AGM or gel cell charger.

When I bought another battery charger / tender, I found that battery type flexibility was one of the things which has now become fairly common.  In some cases, the chargers are even smart enough to detect the battery type on their own.  My NOCO Genius 2 (which was only $50) can handle flooded, AGM, and Lithium, plus 6V.  The lithium setting is likely for golf carts or RV house batteries more than 12v car batteries, but it's nice to have the option.

Yep, my old Husky 6v/12v had to be replaced with a Die Hard brand that does AGM and gel types when I first started working with AGM batteries for my ham radio setups.

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[Moab]

Ya. The only car forum I've hung out on is for the Jeep TJ. So only 97 to 06. With I assume no compatibility issues. 

I would assume the retailers would put a warning on any listing for an AGM replacement into a vehicle if it wasn't compatible. But we all know what happens when we "ass"ume. Lol.

So far I can already see a huge difference in how it starts. And it was onlyabout $70 more than a lead acid.

Lithium would be cool. We just need to up that slave labor in the Congo. And get the orices down.

[majorhavoc]

The battery in my Honda CB500X is an AGM. But in the motorcycling world the creme-de-law creme now is lithium, which weigh a fifth of AGMs and take up about a third of the space.  They're sold with styrofoam spacers so they don't rattle around in a motorcycles "massive" battery box.  I wonder how long before they start showing up in automotive applications? 

Probably not any time soon for car applications, just due to the price.  

Yeah, that makes sense.  Shaving off 10 or 15 pounds on a motorcycle makes a noticeable difference in handling, especially if that weight is high up (most MC batteries are right under the seat).  So I can see how the price premium is more justifiable on a bike.  Of course, the experts all say that before you pay 3x to go from AGM to lithium on your motorcycle, you should do something about that extra inner tube you're carrying around on your waist.  That'll have an even bigger effect on the riding experience ...