Standard flooded or AGM?

mike · Nov 9, 2024

2007 Liberty, a little less than 73000 miles. 3.7, auto. Currently has a 6 year old Super Start Extreme (part no. 34EXTJ) standard flooded battery. No obvious battery issues, I want to replace the battery because of it's age. This is my wife's car, it's driven less than 1500 miles a year. Mayhaps less than a thousand. I'm wondering if I should get an AGM battery? The Super Start Extreme has been real good, and I often (weekly or more) leave a Noco charger/maintainer on it at least overnight, sometimes for a few days. My question is, should I replace the battery with an AGM or get another Super Start Extreme?
Thanks, Mike

LibertyTC · Nov 9, 2024

I stopped buying lead acid batteries many years ago. AGM's tend to provide greater cranking power, especially when it's below freezing.
You won't see corroded terminals on AGM's either.

u2slow · Nov 9, 2024

I'm recently onto the second AGM in the jeep. Pro-actively replaced at 7yrs. Keep it as a shop battery till the end.

Luke · Nov 9, 2024

AGM FTW! … just be aware that they like to receive more volts for proper charging, raising the voltage to ~14v will extend the life of your battery.

mike · Nov 12, 2024

Luke said:
AGM FTW! … just be aware that they like to receive more volts for proper charging, raising the voltage to ~14v will extend the life of your battery.

I'm not sure what all this means, Luke. You say they like to receive more volts. Does this mean that if I switch to AGM I'll also need to change the alternator? I have a Noco Genius 5 tha I use regularly. If I change to AGM will I want to use it from day one?

Luke · Nov 12, 2024

Unfortunately I never had an AGM in my KJ … my current beast is a Toyota FJC. You can use a diode to “trick” the alternator to provide increased voltage … or you can buy a pre made device similar to below. Perhaps the KJ/KK dudes will chime in.

https://voltageboosterpro.com/product/voltage-booster-pro-texas-slim/

KJowner · Nov 13, 2024

I'm fairly sure the charging system on the KJ is controlled by the ECU so fooling it may be difficult.

mike · Sunday at 7:32 AM

KJowner said:
I'm fairly sure the charging system on the KJ is controlled by the ECU so fooling it may be difficult.

It seems that the product Luke mentioned is only for toyotas. I did a quick search for a similar product made for Jeeps. To be honest, most of what I read was way over my head. I did find an interesting comment on a Jeep Cherokee Club page, "One thing we can rely on is that AGMs sold for automotive use are designed to work with past and current automotive electrical systems." That's from 2 1/2 years ago. If this is true, that tells me that an AGM would be fine. All I want to do is replace the battery with one that will last. The Liberty gets driven rarely. This past week, it wasn't driven at all! This is more the rule, rather than the exception. I've had a Noco Genius 5 hooked to it for 2 days now. I'm just looking for the best battery to use in a vehicle that is rarely driven, < 1500 miles a year. If an AGM fits the bill, that's what I'll get. If it's best to keep using plain old batteries, I'll keep using them.

LibertyTC · Sunday at 11:13 AM

Any Group 34 will fit directly into the KJ. Of course the AGM is best.
The best AGM is an Odyssey Battery, but expensive. Odyssey uses virgin lead.
My Odyssey AGM is now close to 13 years old & still fires Jeep right up !!
If you buy the best, it won't die like the rest.

KJowner · Sunday at 11:25 AM

mike said:
It seems that the product Luke mentioned is only for toyotas. I did a quick search for a similar product made for Jeeps. To be honest, most of what I read was way over my head. I did find an interesting comment on a Jeep Cherokee Club page, "One thing we can rely on is that AGMs sold for automotive use are designed to work with past and current automotive electrical systems." That's from 2 1/2 years ago. If this is true, that tells me that an AGM would be fine. All I want to do is replace the battery with one that will last. The Liberty gets driven rarely. This past week, it wasn't driven at all! This is more the rule, rather than the exception. I've had a Noco Genius 5 hooked to it for 2 days now. I'm just looking for the best battery to use in a vehicle that is rarely driven, < 1500 miles a year. If an AGM fits the bill, that's what I'll get. If it's best to keep using plain old batteries, I'll keep using them.

I've had a red top on mine for years, it's lasted well.

u2slow · Sunday at 1:50 PM

LibertyTC said:
If you buy the best, it won't die like the rest.

Not my experience by a longshot.
(Generalized - not a dig at Odyssey.)

reconpatrol · Sunday at 2:43 PM

why not consider Optima red ( as OEM) my first one last over 12 years changed in 2020 , dec .

Luke · Sunday at 5:54 PM

mike said:
It seems that the product Luke mentioned is only for toyotas. I did a quick search for a similar product made for Jeeps. To be honest, most of what I read was way over my head. I did find an interesting comment on a Jeep Cherokee Club page, "One thing we can rely on is that AGMs sold for automotive use are designed to work with past and current automotive electrical systems." That's from 2 1/2 years ago. If this is true, that tells me that an AGM would be fine. All I want to do is replace the battery with one that will last. The Liberty gets driven rarely. This past week, it wasn't driven at all! This is more the rule, rather than the exception. I've had a Noco Genius 5 hooked to it for 2 days now. I'm just looking for the best battery to use in a vehicle that is rarely driven, < 1500 miles a year. If an AGM fits the bill, that's what I'll get. If it's best to keep using plain old batteries, I'll keep using them.

It is yes… I also saw that post while searching for a Jeep solution. Without any reference to a source it’s difficult to assess it worth. You could check your alternators charging output with a decent voltmeter to get a baseline and then inquire with the battery manufacturer as to suggested charging voltage.
To be clear an AGM will be “fine” but if you want to keep it healthy for longer increased charging voltage is recommended.
As an aside you mentioned your short trips… this is another benefit to increased charging voltage, it handles that driving style better and you won’t need your Noco as much.

Luke · Sunday at 6:10 PM

Excerpt from the Odyssey AGM Technical Manual. Note the 14.2-14.5 volts. I could only achieve that with a voltage boost. It gets even more imperative as the temperature drops.

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mike · Monday at 8:34 AM

Thanks to all. Lots of info to study. Thankfully it's not a need one now situation, I'm just planning ahead. My other car is a 2021 Ford Escape with the original (AGM) battery, it needs replaced soon. If I replace the Liberty battery first, mayhaps I won't be buying two batteries at once. Hopefully I can get a year between purchases.

mike · 2024-11-20T08:35:31-0500

Luke said:
You could check your alternators charging output with a decent voltmeter

How do I check this? You mention a voltmeter. I have a Fluke77 multimeter. Will that work?

KJowner · 2024-11-20T09:16:35-0500

mike said:
How do I check this? You mention a voltmeter. I have a Fluke77 multimeter. Will that work?

A Fluke will do nicely, switch it to DC and measure the voltage at the battery terminals.
I'd guess you wouldn't see much more than a fluttering 13.5v as the ECU runs as an AVR on our setup.
As I said earlier, I've had a redtop on my CRD for years and it's been excellent, the specs for charging it are a bit lower than the Odyssey at 13.3v so it's probably more suitable for a Jeep.

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mike · 2024-11-21T09:00:42-0500

Thanks KJowner. I'll give it a try. I'm guessing that when I use the Fluke it's with the engine running. I think I've decided to get an Optima RedTop. What do you mean by: "as the ECU runs as an AVR on our setup."? I see you have a CRD, mine is a 3.7 gas.

KJowner · 2024-11-21T16:06:18-0500

The ECU controls the voltage supplied by the alternator the same way to the Automatic Voltage Regulator on a generator controls the voltage by varying the field strength. It's the same system on the gas and diesels. Why they decided this was necessary instead of a conventional regulated alternator I don't know, I guess it's because the PCI bus runs at nearly battery voltage so needs a very stable supply???

Standard flooded or AGM?

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