Way to fragile with over discharging. Alternator failed and battery stayed charged enough to get me home BUT the battery was 3 months old and never had any other discharging. It was tested frequently by me about weekly and even charged it monthly with an appropriate smart battery charger to maintain it prior to this . Battery is unrecoverable after ONE discharge (and not a left on side of the road discharge. In fact the alternator was working intermittently, Iike at stop lights voltage would creep up to near normal). NOW the budget Walmart battery it replaced failed during a freezing stent after only one year which is why I went with a good AGM to begin with. Well guess what, put that old cheap Walmart battery on the charger in recovery mode and not only does it test good consistently, it starts the truck every time and it’s consistently testing at 810CCA (rated at 650CCA). That is more than the twice as expensive AGM battery rated at 775CCA EVER tested even on day one (it typically tested around 720CCA. Even if a cheap flooded battery last half as long, it’s half the price so what exactly am I gaining with an AGM ESPECIALLY since the AGM is apparently intolerant of mishaps.
No more AGM batteries for me
- Thread starter stanlee
- Start date
AGM has slightly different charging requirements. It may not be suitable replacement for your vehicle but there are many that get their lifespan out of them no problem. My 75Ah deep cycle batteries on my basement sump pump have been idle for 6 years 7 months. Now that is in a cool basement just on float voltage of 14v so not a vehicle app. Are your daily drives long enough to recharge? Does your engine run real hot under the hood? It was a WM AGM brand EverStart? You also had a previous battery fail early in the same vehicle?
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Which "good" agm failed after one discharge?
Its possible that it froze when discharged. Since the plates and separators are next to each other, I can imagine freezing causing damage easier with an agm.
But, any battery can be ruined if discharged and frozen.
The freezing point temperature becomes much higher when a battery is discharged.
But, any battery can be ruined if discharged and frozen.
The freezing point temperature becomes much higher when a battery is discharged.
I'm not an expert, but my experience is that a failing alternator can really wreak havoc on a battery.
While I'm here, I'd like to thanks Bosch for selling their alternator business to the chinese and costing me not just two alternators but two batteries as well!
Thanks for listening to my TED talk.
While I'm here, I'd like to thanks Bosch for selling their alternator business to the chinese and costing me not just two alternators but two batteries as well!
Thanks for listening to my TED talk.
I've had a fair bit of experience and research on AGM and it's definitely my preferred choice for MOST lead-acid applications. If I'm spending time & money replacing a battery I want it to be high value & performance.
Where NOT to use AGM:
- high temperature environments
(most specs list 60C as the upper recommended operating limit)
- unregulated, non-optimized charging systems
(overcharging or fixed voltage, 14.4v systems)
Where NOT to use flooded lead-acid:
- high vibration, high G environments
(power sports, off-road, etc)
- high value / sensitive / long-life equipment
(corrosive off-gassing causes constant damage)
- high performance applications
(power / weight priorities)
- remote areas / installations
(AGM can be shipped ready to go by courier, etc)
- limited mounting options / space
(AGM can be installed sideways, inverted)
Where NOT to use AGM:
- high temperature environments
(most specs list 60C as the upper recommended operating limit)
- unregulated, non-optimized charging systems
(overcharging or fixed voltage, 14.4v systems)
Where NOT to use flooded lead-acid:
- high vibration, high G environments
(power sports, off-road, etc)
- high value / sensitive / long-life equipment
(corrosive off-gassing causes constant damage)
- high performance applications
(power / weight priorities)
- remote areas / installations
(AGM can be shipped ready to go by courier, etc)
- limited mounting options / space
(AGM can be installed sideways, inverted)
Also, AGM does not mean quality / performance. You can definitely get poor results from any battery type.
Wife's current vehicle with start-stop has an Enhanced flooded battery we had a loaner with start-stop also EFB. Which OEM's are using AGM off the assembly line? Big dollar rides like BMW and Benz? I would not upgrade to an AGM if my vehicle wasn't equipped with one most likely the vehicles charging system would never charge the AGM correctly or develop some other wonky charge related issues.
So will WM replace it?
I'm in this camp of replacing the battery with the same chemistry as it came with from the factory. An H6 AGM came with my RAV4 and that's what I bought when the battery got weak.
Odd, I've found quality AGM's more durable for limited use and relatively deep cycling than flooded and I never had a problem with running them on many older cars, boats and an airplane not originally equipped for them. Every toy in the fleet has or had them w/ one failure in 25 years; Optima Yellow Top. I would say the problem lies elsewhere (system, freezing as noted) or it was a bad battery.
I am very picky about which ones I buy and I won't mention brands because suppliers change frequently or by location. That said, flooded batteries are fine for most applications. And that said, I am putting an H8 AGM in a 1979 car later this week.
I am very picky about which ones I buy and I won't mention brands because suppliers change frequently or by location. That said, flooded batteries are fine for most applications. And that said, I am putting an H8 AGM in a 1979 car later this week.
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That’s an interesting fact you bring up I just recently had a situation. My wife’s car was at the dealer for 17 days to take care of a recall got the vehicle back turn over felt weak put it on a smart charger based on resistance and charge characteristics the charger automatically went into AGM/GEL mode and this was the EFB. Therefore installing an AGM in a EFB equipped vehicle may be a beneficial upgrade don’t really know but it’s definitely a questionable topic of debate and if the vehicles charging system can adapt and handle charging the AGM.
I don't mind a rant.
Run on paragraphs with no actual data are an annoyance.
Run on paragraphs with no actual data are an annoyance.
I just put an H8 in the Volvo last year. Spins up the starter quick!
Walmart most times also has an AGM, depending on brand ,AGM is excellent over standard lead acid, and why they are used.
Agm's are very cheap nowadys for motocycles(cause of lithium ones out). The car industry though is raking people over the coals on AGM prices.
Cars now adays have so much electrical and electronics , regular lead acid likely not going to cut it.
Agm's are very cheap nowadys for motocycles(cause of lithium ones out). The car industry though is raking people over the coals on AGM prices.
Cars now adays have so much electrical and electronics , regular lead acid likely not going to cut it.
I put a walmart AGM (clarios) in my truck a couple years ago. 2011 Nissan, no special charging. So far so good. The heat here kills regular lead acid fairly handily so we shall see.
It was only $30 more than the same size lead acid and has an extra year of replacement warranty.
Since AGM and flooded batteries are both the same chemistry (lead-acid) why would they not be completely interchangeable?
The AGM batteries can typically tolerate more aggressive current draw, but as far as charging goes, since they are the same chemistry I was under the understanding that a charger (or alternator) built for one will work fine on the other.
The AGM batteries can typically tolerate more aggressive current draw, but as far as charging goes, since they are the same chemistry I was under the understanding that a charger (or alternator) built for one will work fine on the other.
How 'bout a "What'd my car come with originally?" list? (ha-ha)
I have a battery monitoring system which features nascent electronics which make the clamps look clunky.
There's a wire which runs across the top of the battery-from one cluttered post clamp to the other.
I believe infrequent use early in its life has led to a recurring "low battery voltage" warning. It'll be 12.4v and starts the car heartily.
After use, the warning doesn't return. She mornings at 12.6v when in use.
This is a 1.5-year-old AGM battery.
There's a disconnect on the aforementioned wire which short vids show as a reset to address the warning.
I haven't done it yet as the car is underutilized. I want a longer chain of data.
With regular use, the warning might not return.
I do want to see if a replacement wire is available as it is under hood and could be brittle and break.
I have a battery monitoring system which features nascent electronics which make the clamps look clunky.
There's a wire which runs across the top of the battery-from one cluttered post clamp to the other.
I believe infrequent use early in its life has led to a recurring "low battery voltage" warning. It'll be 12.4v and starts the car heartily.
After use, the warning doesn't return. She mornings at 12.6v when in use.
This is a 1.5-year-old AGM battery.
There's a disconnect on the aforementioned wire which short vids show as a reset to address the warning.
I haven't done it yet as the car is underutilized. I want a longer chain of data.
With regular use, the warning might not return.
I do want to see if a replacement wire is available as it is under hood and could be brittle and break.
f355spider
$50 Site Donor 2026
My experience as well. I use AGMs in everything and haven't had any short life issues. Currently have AGM in my 25 yo BMW that is 7 years old AC Delco (Clario/Varta made in Germany). Only Optima red top AGM have I had issues. Had three of them leak in a row...all less than two years old. But they stilll worked fine and held a charge. In fact the only other early failures I have had were with East Penn flooded in H8. Two in a row, less than two years life.
Because, they operate at slightly different voltages.
A fully charged AGM is typically about 12.8 - 12.85 where a fully charged lead acid is about 12.7.
