Poor AGM Battery Service Life

I've had two different Deka AGM's fail in well less than a year. That was about 10-11 years ago. Daily driven vehicle. I swore I'd never have another AGM in a car or a truck, but I got a Deka AGM on a online shipped order in 2020. Good for more than a year. Deka warranty is only 30 months, however.

Nothing but great luck with AGM's on motorcycles.
 
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tried anybody this ???:love:
like in car or backup supply ?
 
It's who makes the AGM not being a AGM. My '16 Equinox, OEM AC battery bad at 3 yrs. . OEM AC in my '11 Tahoe got pulled at 7 yrs. due to age only and not wanting to risk a no start at sub zero temps. . It's in the garage on a BatteryMinder and saw lighting duty in my camper this summer.
AGM in one of my snowmobiles, OEM Yuasa, and the OEM AGM battery in my Harley got replaced at the age of 10 yrs. . And not due to a no start but due to their age and not wanting to get stuck. Used the maintained sled battery to jump my dead JD mower last week as it's great for portable 12v power when working on trailer lights.
I've been using Odyssey brand for replacements whenever possible. Just put one in my Generac stationary whose 3 yr. old AZ just tossed a code in it.
Absolutely so! Odyssey IMO is the best followed by NorthStar
 
Interesting. I have been a bit worried about the AGM battery in the 2015 Mini that I bought half a year ago. The battery, the factory BMW-branded AGM, is original and the car had been barely used for several years. It had only 5k miles on it when I bought it. The battery is however going still strong. I have heard AGM batteries can fail rapidly.

Same with the OE AGM in our 2012 Cooper. Still the factory one installed,
still going strong. Car is used 6 days a week, many short trips. Disabled the
bloody start/stop crap though. Some batteries die young, some have a long
life. Has it been any different in the past?
.
 
Car is driven 4-5x/week and battery is trickle-charged twice a month.
Battery is possibly heavily sulfated. Have you checked the voltage and current from the alternator and the trickle charger. Are the car trips short? 30 minute trips will not fully charge the battery.
 
Battery is possibly heavily sulfated. Have you checked the voltage and current from the alternator and the trickle charger. Are the car trips short? 30 minute trips will not fully charge the battery.
That would not surprise me. The trips are 15 minutes at moderate speeds.

My point is: if a conventional battery can provide the same lifespan under these conditions, what is the advantage of AGM?
 
Those cycling batteries in the marine world, have come to realize that AGMS are more finicky than flooded. They need to be returned to true full charge more often than flooded, and partial state of charge deep cycling of them is far more detrimental to them then flooded deep cycle batteries.
PSOC cycling means starting the next discharge cycke before having been returned to 100% state of charge.
PSOC cycling causes the battery to have less and less total available capacity, and it also increases the time it takes to return the battery to truly full. 10 deep cycles in a row only getting back to 85% charged and the battery bank is punch drunk

Agms are still desirable as deep cycling batteries for those who have concerns of offgassing, terminal corrosion, or have difficulty accessing/ remembering to access the flooded batteries to water them before the plate tops get exposed. As Flooded batteries age, they require more time at absorption voltages to reach full charge, and thus use more water, and require checking of their levels far more often.

Few batteries perform well after plate exposure, that exposed portion basically becomes useless in most cases, even once refilled.

AGMS can, at the same voltage, charge faster. Especially when depleted, they will be able to get to 85% charged faster than their flooded counterpart, ( if the charging source can feed them the higher amperage they can accept) but the 85% to 100% range always takes hours and AGMS have no significant advantage in this range.

Many cheaper AGMS say no more than 30 amps charge current per 100 amp hours of capacity
The much revered and often relabelled bitog favorite, the Deka Intimidator, is one such battery.


High $$ AGM Batteries such as Lifeline, Odyssey state specifically, in deep cycle usage, a minimum charge rate, with Lifeline stating no less than 20 amps per 100Ah of capacity, and Odyssey stating no less than 40!

how does this relate to an AGM used only as a starting battery, never intentionally deep cycled.
good question.

Lab coats, expensive tools and lots of time and testing and experiments would be required to answer it accurately.

My take on AGMs is they need the occasional workout. Drain them to 12 volts with a 15 amp load and immediately apply 20+ amps to them, but then once their voltage rises to 14.4 to 14.7v, hold it until it tapers to 0.5 or less, then float at 13.6v until amps taper to zero.

I spoke with an Odyssey technical assistant and he was adamant that if one could not float their battery at 13.6v, to not float it at all, just remove the loads and let it sit, as AGMS , especially high $$ AGMS have such low self discharge.

Odyssey states 13.6v float voltage @ 77f, same with Northstar, Lifeline is a bit lower ar 13.2 o 13.4.
most flooded batteries say float at 13.2v or near there

My AGMS get lazy when I keep them at their prescribed float voltage for days on end, then cycle them.
Their voltage retention, powering high loads like the starter motor, or lesser loads like a refrigerator after days floating, is not as good as hoped for.
When I get annoyed at the voltage retention, considering the amp hours used and the size of the existing load, I will intentionally take the battery down to 50% charged or less, then hit them with high amperage. I have upto 140 amps of plug in adjustable voltage charging sources and two 120 amp alternators, whose voltage I manually control.

Every time I high amp recharge my AGMS, even the Dekas that say no more than 30 amps per 100Ah of capacity, their performance returns, they can maintain higher voltage when powering loads like the starter, or an inverter powering a Skilsaw, or a dc refrigerator overnight.
My 190 amp hours of 5 year old Dekas can accept 116 amps when depleted to 50%
My 103Ah of TPPL Northstar AGM, just turned 3 years old, can still accept 140+

AGms if deeply cycled and fed ONLY low and slow charging currents will be tickled to death.
If they are never discharged much, % wise, they will never be able to accept high charge currents.
Perhaps this is a contributing factor in their less than expected service life even if they are kept at relatively high states of charge.
 
AGms if deeply cycled and fed ONLY low and slow charging currents will be tickled to death.
If they are never discharged much, % wise, they will never be able to accept high charge currents.
Perhaps this is a contributing factor in their less than expected service life even if they are kept at relatively high states of charge.

So, we have both opinions -- keep the batteries at very high SoC at all times and they'll last a very long time, and DON'T keep them at very high SoC all the time or they'll fail prematurely. :unsure: Hard to know what to do. My only AGM application is in my vehicle. Especially with recent usage patterns, I put it on my CTEK in the garage a lot to keep SoC high. By design the vehicle targets 80% as max SoC based on active battery management so leaving it to the vehicle charging system alone will never, ever reach 100% SoC. The system voltage target is 14.8VDC if it believes SoC is
This battery was new in July 2015 45k miles ago. I realize by time this battery owes me nothing and I've been thinking about replacing it for a while but it seems to be doing "OK" (and, in my market at least, battery prices have gone crazy. Like over $600 for a 95R/H9 battery alone cash&carry to get a Deka from one of the local retailers). Last week I had to use the starter to perform an oil system priming procedure with full compression (i.e. plugs in, fuel injectors disconnected). It did 5x 10s cranking operations with 1min starter cool downs in between. System voltage stayed in the 10.9-11.1 range while cranking in 5C temperature conditions. That was a pretty good battery workout compared to the typical 2s starting sequence. I guess the question is whether the battery is still up for normal starts in -20C at, say, 60-70% initial SoC...

I don't want to be stranded, nor do I want to unnecessarily replace a battery whose replacement is inflated to ridiculous pricing (hopefully temporarily). If I don't replace it, I'll at least make sure I have cables in the trunk all winter. :)
 
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...how does this relate to an AGM used only as a starting battery, never intentionally deep cycled.
good question.
Lab coats, expensive tools and lots of time and testing and experiments would be required to answer it accurately.

A ton of research has been done over the last 15 years on PSOC operation of lead acid batteries in vehicles. A search using Google Scholar will turn up thousands of research papers and books. Based on that research, the global automotive industry has embraced the AGM battery and the Enhanced Flooded Battery.

A few examples chosen at random:



 
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Thanks Critic, shopping a battery for the wife's car. $119 for conventional, $159 for AGM at Walmart.

Will go with the conventional and 3 year replacement warranty.
 
In March 2015, I replaced the original AGM in my Prius with a $65 generic U1 AGM, which is a little smaller than the original (which is the same size as a 51 or 51R). It's still doing its job, occasional inadvertent abuse notwithstanding.
 
My Cruze calls for a 94R/H7 and is one monster battery. I assume because the car has start / stop, but I have it disabled in my tune. It lives in the bottom of the hatch so less exposure to heat in the engine bay. Going to monitor it, but it seems really strong still. I did short trip the car, and as of late drive less but when I do get out its usually longer highway drives. I think its 850CCA so I think having some to spare helps as well. I just cleaned and coated the terminals and it looked great, for whatever that is worth.

After this winter I might think about replacing it. Walmart seems to be the best deal to replace it, might go that route.
 
My Cruze calls for a 94R/H7 and is one monster battery. I assume because the car has start / stop, but I have it disabled in my tune. It lives in the bottom of the hatch so less exposure to heat in the engine bay. Going to monitor it, but it seems really strong still. I did short trip the car, and as of late drive less but when I do get out its usually longer highway drives. I think its 850CCA so I think having some to spare helps as well. I just cleaned and coated the terminals and it looked great, for whatever that is worth.

After this winter I might think about replacing it. Walmart seems to be the best deal to replace it, might go that route.
Don't guess. Get it load tested and see how it holds up. Like I said, my AGM H8 battery is still going after 14 years. AGM batteries don't really vent so you don't get any corrosion on the terminals. Mine still look brand new.
 
I’ve been loosely following this thread. I’m replacing the battery in the Lexus and it likes to hang out around 13.9 volts once warmed up. I don’t have frequent battery replacements, despite living in a warmer climate, so I’m going with X2/North Star AGM. have found that toyota products have a fuse, ALT-S, which is a specific fuse for the voltage sense input to the regulator. One can replace that fuse with a fuse-shaped fuse/diode used in GM makes. For those who don’t know, a typical diode has about 0.7volts drop over it. Inserted into the sense lead, it artificially lowers the resultant sense voltage. Doing so would bring the lex to roughly 14.5, which is in spec for the X2/North Star agms.

this car gets short tripped and I’ve had starting trouble with it last winter unless I charged it in the garage regularly. frankly, the diode alone with a flooded battery would likely be all it needs to meet this use cycle, but I’ll spring for the premium battery because I’d like the experience of seeing how it does.
 
Don't guess. Get it load tested and see how it holds up. Like I said, my AGM H8 battery is still going after 14 years. AGM batteries don't really vent so you don't get any corrosion on the terminals. Mine still look brand new.
Can parts stores even accurately test batteries?

My battery is a bit of a bear to remove.
 
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