When AGM batteries die is it always suddenly?

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I've had two AGM batteries and they were good, always held a charge and then just suddenly failed. Even with a jump start the engine wouldn't run properly, they would idle but not take much load when you drove off without dying.
Never had that problem with a traditional lead acid battery.

Have I just been unlucky with some sort of internal battery short in the AGM batteries I've owned or is there more to it.
The reason I ask is that I'm using another sealed AGM battery that's now about 9 years old,
that's performed flawlessly holding enough of a charge even after a couple of months disuse to always start the car. I just don't want to be left stranded with sudden battery failure.
 
Which brands are these?

I would also like to know about this, and what exactly is the voltage of a 'dead' AGM, as compared to a conventional lead acid deal (ARE they different)???
 
Are these Optima batteries? In the various auto forums I visit, I have read of sudden battery failures for all types of batteries, not just AGM. I guess we will have to carry a spare battery, along with our spare tire.
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I have had Exide Orbital batteries do that,suddenly no cranking speed or power and recharging them does nothing.
Exide has since dumped spiral cell technology in favor of AGM flat plate design.Something about more surface area...more power and all that stuff.I say its because Exide is in bankruptcy again and needs to cut costs everywhere it can.
 
Dead battery. I always put mine on a 2 amp charge over night, if possible. A cars alternator is not made to charge a dead battery.
 
Originally Posted By: dailydriver
Which brands are these?

I would also like to know about this, and what exactly is the voltage of a 'dead' AGM, as compared to a conventional lead acid deal (ARE they different)???

The first battery was a British sealed Exide battery that lasted 9 years.
The second was an Interstate (Yuasa) motorsport battery that lasted only 4 years.
It's been a view years ago now and I did measure the voltage at the time. The Interstate battery IIRC still read 13 volts and I don't recall if the car would start without a boost but the real problem was that it wouldn't run properly and I had to nurse the car home about 100 miles following a friend like that. At one point I couldn't do more than 50 mph without the engine cutting out but it did improve as I got closer to home to the point that it would run properly.
But once I got home, again IIRC I don't think the battery would restart the car and I replaced the battery with another AGM`, the same one I'm using now.
 
I don't think that this is a problem exclusive to AGM batteries.
I've seen sudden death on most sealed batteries we've had.
They're fine until they're not, without much warning, if any.
I'd be looking at an alternator problem if the car ran poorly once it was running.
The battery isn't doing much once the engine is being run with enough revs to produce enough alternator output to run all of the car's essential systems.
I've had bad batteries and the car was always fine once you got it started by either rolling it down a hill and letting the clutch in, getting someone to push it and doing the same or after a jump start.
If you had problems with the car running once started, you may have a bum alternator.
 
Originally Posted By: CATERHAM
Even with a jump start the engine wouldn't run properly, they would idle but not take much load when you drove off without dying.


This sounds more like an "I tried jumpstarting a BMW" problem than an AGM problem. If it was a BMW, well, next time use a better power source for the jump. If that doesn't work, let it idle for a few minutes, shut it off, then restart it. They seem to like that.
 
Originally Posted By: LargeCarManX2
I believe AGM batteries need to be on a slow trickle charge most of the time when not in use.


This will help them. AGM batteries do not stand being discharged (they lose a little life), so use a trickle charger if you let them sit unused.
 
Originally Posted By: fdcg27

I'd be looking at an alternator problem if the car ran poorly once it was running.
The battery isn't doing much once the engine is being run with enough revs to produce enough alternator output to run all of the car's essential systems.
I've had bad batteries and the car was always fine once you got it started by either rolling it down a hill and letting the clutch in, getting someone to push it and doing the same or after a jump start.
If you had problems with the car running once started, you may have a bum alternator.

Nope, no alternator problem or any other problem once the battery was replaced and it's happened twice four years apart. That's why I'm somewhat nervous about the 9 year old AGM I'm currently using.
I have no problem if it just dies, as your say I can always get a jump or bump start the car assuming the car will RUN PROPERLY and THAT'S BEEN THE PROBLEM IN THE PAST AND WHAT I'M NOW CONCERNED ABOUT.
 
There is a LOT less electrolyte in there, so some chemistry that might be disgussed in the flooded chemistry might be more abrupt.

My 91 BMW seems to undercharge batteries and this causes them to degrade gracefully but definitely... Im seeing this right now for a group 40 battery. So the failure isnt always immediate.
 
Originally Posted By: Corvette Owner
Originally Posted By: LargeCarManX2
I believe AGM batteries need to be on a slow trickle charge most of the time when not in use.


This will help them. AGM batteries do not stand being discharged (they lose a little life), so use a trickle charger if you let them sit unused.



AGM batteries have SLOWER self-discharge, so sitting off a charger can be done for longer, which is a good thing.

ALL lead-acid batteries lose life rapidly when uncharged or undercharged.
 
Originally Posted By: SubLGT
Are these Optima batteries? In the various auto forums I visit, I have read of sudden battery failures for all types of batteries, not just AGM. I guess we will have to carry a spare battery, along with our spare tire.
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Ever since production moved to Mexico, Optimas are junk now. I had one that lasted 1.5 years. My friend had one in his car for 2 years before it suddenly quit. He has about a year on his replacement, so we will see how long that one lasts.
 
The spiral cells have one major drawback. There is only one grid per cell. It that breaks loose at the internal busbar, or internally in the wrapped cell the battery goes OC.
 
Originally Posted By: CATERHAM
Originally Posted By: fdcg27

I'd be looking at an alternator problem if the car ran poorly once it was running.
The battery isn't doing much once the engine is being run with enough revs to produce enough alternator output to run all of the car's essential systems.
I've had bad batteries and the car was always fine once you got it started by either rolling it down a hill and letting the clutch in, getting someone to push it and doing the same or after a jump start.
If you had problems with the car running once started, you may have a bum alternator.

Nope, no alternator problem or any other problem once the battery was replaced and it's happened twice four years apart. That's why I'm somewhat nervous about the 9 year old AGM I'm currently using.
I have no problem if it just dies, as your say I can always get a jump or bump start the car assuming the car will RUN PROPERLY and THAT'S BEEN THE PROBLEM IN THE PAST AND WHAT I'M NOW CONCERNED ABOUT.


This DOES sound like your alternator is not putting out enough current/amps for your car's usage, EVEN IF it is functioning perfectly within it's RATED output, and is drawing amps from the battery to make up the difference (if it is running poorly once the battery is going out).
Are these OEM size/rated alternators, or did you install smaller/lighter/lower output models (less drag on belt drive/engine, hence more power to the wheels) for racing/performance reasons??
 
while it is made with continuous grids they have several connecting points on each that all line up once the plate pair is wound.those get cast together as part of an interconnect or post.
the big killer is water loss that accelerates corrosion.this takes out an interconnect.
remember the acid becomes more concentrated as you lose water.i get these types of battery often that are testing poorly but have an unusually high oc voltage at rest after being fully charged.i carefully add small amounts of water and let it soak in.then do an impedance test.if still poor i give each cell another dose of water.if its still not improving its just worn out.most improve a lot.many like new.
Originally Posted By: SHOZ
The spiral cells have one major drawback. There is only one grid per cell. It that breaks loose at the internal busbar, or internally in the wrapped cell the battery goes OC.
 
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My experience lately with plain lead acid batteries is that sudden death seems much more common than it was 30 years ago. Almost never seem to get that telltale slooow crank. Just go out one morning and click,click,click.

I am trying a BatteryMinder now and hope to see if that gives me any extended service.

And I DO pry the caps off and add distilled water in spite of some warnings on here.
 
Originally Posted By: kc8adu
while it is made with continuous grids they have several connecting points on each that all line up once the plate pair is wound.those get cast together as part of an interconnect or post.
the big killer is water loss that accelerates corrosion.this takes out an interconnect.
remember the acid becomes more concentrated as you lose water.i get these types of battery often that are testing poorly but have an unusually high oc voltage at rest after being fully charged.i carefully add small amounts of water and let it soak in.then do an impedance test.if still poor i give each cell another dose of water.if its still not improving its just worn out.most improve a lot.many like new.
Originally Posted By: SHOZ
The spiral cells have one major drawback. There is only one grid per cell. It that breaks loose at the internal busbar, or internally in the wrapped cell the battery goes OC.


HOW do you get the water in there, through the dense sponge covered vents in the top???
21.gif
 
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