98 Wrangler - starting / battery issue

[83 Shellback]

Long story short, garaged / not-in-use 98 Wrangler Sahara. Battery dead (understandable)

Charged battery. Starter died while cranking in attempts to start (+25 yrs old). Replaced starter, then battery. Started okay, drove a short distance (maybe 5-10 miles) and put back in garage. Wasn't too concerned with it being unused in the garage since I have a charger and can jump from another vehicle. Also, figured I'd start it every month or so (failed to do that).

Fast forward to recent. Now, I have it on a tender to keep the battery topped off. When I try to start it, it cranks over once from a full charge and then battery dies (clicks like drained battery or maybe solenoid issue).

Jumped it and took it to a nearby shop. Figured alternator since it didn't seem to be charging the battery - though, admittedly, I probably didn't drive it far enough to charge the battery. Think if it jumpstarts okay, that means the solenoid is probably ok..

Anyway; Shop just called me and said the alternator is fine - the problem is that I have an AGM battery but those are for vehicles with a lot more technical requirements than my 98 Wrangler (touchscreens, backup cameras, heated seats, etc.) which has none of that. Said AGM batteries sometimes don't charge properly from the original alternator in the Jeep. They also said the battery wasn't charging (said it showed 0%).

Approved getting a new, non-AGM battery, but does that sound legit?

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[cj7ox]

Nope! I run AGM batteries in my 85 CJ7. After sitting for a long while they will die. Never had a problem with my alternator charging the battery when in regular use. It may be the battery had died from neglect. It could also be the trickle charger used. I seem to recall that not all trickle chargers make AGM batteries happy, but have no empirical knowledge.

 

[83 Shellback]

Just noticing my charger has a AGM setting, which.. I didn't use. Didn't know what an AGM battery even was.. thought it was some kind of boat battery or something. Bleh.

Thanks for replying.

 

[THAW]

Anyway; Shop just called me and said the alternator is fine - the problem is that I have an AGM battery but those are for vehicles with a lot more technical requirements than my 98 Wrangler (touchscreens, backup cameras, heated seats, etc.) which has none of that. Said AGM batteries sometimes don't charge properly from the original alternator in the Jeep. They also said the battery wasn't charging (said it showed 0%).

Approved getting a new, non-AGM battery, but does that sound legit?

It sounds mostly legit.

Alternator charging is rarely optimal for an AGM battery (due to driving-habit-based charging cycles if not intrinsic design compromise), and voltage regulation in non-modern vehicles is likely to be particularly poor for maintaining one.

An AGM battery can certainly be used in a vehicle not originally designed for one, but in general AGM batteries are more expensive than flooded acid batteries so (especially) in such applications it's wise to prolong battery life by occasionally using a properly-sized (in Amps) external charger with an AGM profile.

Either way, based on the history you described, you likely need a new battery.

 

[83 Shellback]

It sounds mostly legit.

Either way, based on the history you described, you likely need a new battery.

Yep. I probably ruined the battery by leaving it in unused the garage and not using a trickle charger on it. Learned a few lessons here.

Thanks for replying.

 

[alphawolff]

I'd suspect a starter issue or possibly a block ground issue. Odd for a new battery to fail that quickly.

AGM batteries HATE being discharged, so if you've let that new battery go flat once already it might not hold much of a charge anymore.

 

[83 Shellback]

I'd suspect a starter issue or possibly a block ground issue. Odd for a new battery to fail that quickly.

AGM batteries HATE being discharged, so if you've let that new battery go flat once already it might not hold much of a charge anymore.

Yeah, it got fully discharged sitting in the garage. That took place over the course of a year or longer maybe. Not sure when I put the battery in, honestly, but I also didn't expect a battery to die in that short a time. And, figured it'd charge up with no problem.

Replaced the AGM yesterday with a standard flooded cell [Interstate MT-34]. Starts like new. Have it on a tender currently. Will see how things go.

Thanks for replying.

 

[83 Shellback]

Got a shiny new Interstate battery installed in the Jeep now, and all is well [for now].

As we all know: Jeep is just a registered acronym "Just Empty Every Pocket".

Happy JEEP'ing, and thanks for the replies. Lord knows I need a sanity check from time to time.

 

[alphawolff]

Yeah, it got fully discharged sitting in the garage. That took place over the course of a year or longer maybe. Not sure when I put the battery in, honestly, but I also didn't expect a battery to die in that short a time. And, figured it'd charge up with no problem.

Replaced the AGM yesterday with a standard flooded cell [Interstate MT-34]. Starts like new. Have it on a tender currently. Will see how things go.

Thanks for replying.

I didn't realize the new battery sat for a year, lol. Nice work.

 

[mishkajb]

If you've heard of OPTIMA batteries, then you know about AGM (absorbent glass material). It still uses an acid solution for electrical storage, but doesn't require refilling like the old-fashioned lead-acid (flooded) battery.

My uncle used to work for Interstate Batteries. When OPTIMA first came out, they would get several returns, saying the battery was defective. They cannot be recharged from "0%". They require a special charge/discharge cycle to bring them back to operating conditions. IIRC, if it goes below 25%, you can't recharge it with a traditional straight voltage charger.

Here's a little more info on AGMs - https://www.optimabatteries.com/experience/blog/what-does-agm-mean-on-a-battery-charger

And let us know if changing your trickle charger to AGM reconditions the battery!

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