Done with AGM batteries!
1. Optima YellowTop--5-6 yrs.
2. Optima RedTop--15+ years!
3. Exide Edge--5 yrs.
4. Deka Intimidator--3yrs!
Conclusion? AGMs not worth it.
Full story (but for those who want my detailed experiences before they believe me that they're not worht it):
For the people that believe the marketing and all the technicalities of why they should be better? I'm just going to say, "don't be me." I was one of those people for going on like two decades now, and yes they should be better, but really they have not been any better in the real world.
Let's do full rundown of the four AGM batteries I've purchased over the years.
1. First was an Optima YellowTop 34/78 this was probably in 2002 or so I'd say. Bought on intarwebs from an Interstate dealer way back in the day where Interstate was the main distributor for the little-known Optima Battery company (before they were bought out by JC) . Bought it due to it being touted for car audio applications and back then I was a big "car audio guy" I guess you could say so when the battery in my car failed some 5-6 years into the car's life, this is what I bought. Long story short the YT battery lasted...about 5-6 years. Not really any longer than the OE flooded battery that it replaced. I chalked it up to being a not-so-great individual example and/or that it wasn't as good as the Red Top for a regular car application. The shorter warranty of the YT even suggested this. I don't remember what it cost me but it was somewhere around $100 USD which seems like a great deal but at that time that was about $160 CAD and then whatever that ends up being when you account for inflation--probably $200 or so.
2. Anyway, while I had the YT, I actually bought a RedTop 35/75 at Walmart in Canada in 2004 for the low price (relative to what they cost these days) of $130. Walmart Canada has an exclusive warranty for RTs at the time which was 3yr replacement and 10yr total warranty--10yrs being virtually unheard of at the time. I had bought the battery for a "project car" that never ended up panning out and the car was sold as-is, so the battery I'd used a little bit in that car, I kept. It sat for a couple years and then when I got a new car and because I'd put an audio system in that car right away I took out the factory battery and used the RT. In late 2012 the car was written off so I took the battery out and put the stock one in, at the body shop. 8yrs later that battery was still going strong.
3. Sometime, in the middle of all this I bought another AGM, a CT AGM battery that was really a rebadged Exide Edge. This went in the car I purchased in 2012 to replace above mentioned vehicle (note I bought the battery a year or two before this though). This one had a 5yr replacement warranty with no pro-rated portion. About 3-4yrs in I felt like it was getting weak but I was in denial because again I'd drank the kool aid I guess and thought AGM should last like 8-10 years on the long run. But my suspicions grew stronger as it seemed quite weak after leaving it parked daily for 8-10hrs in the winter at work everyday. I even swapped out the "old" RT and low and behold that battery was like 5yrs older than this one and was cranking stronger!
So, I borrowed a carbon-pile load tester (I have my own electronic one now but then I didn't have any load tester). Sure enough it was quite weak. The much older, lower-specced (it was smaller) RT was actually testing better than this battery. I scrambled to find my original receipt which I eventually did and got a replacement...on the very last day of the warranty. Now there used to be a "trick" that if the person at CT didn't know what they were doing you could get a full warranty on the replacement battery, but I didn't luck out as a manager that knew what they were doing did my transaction so the new battery had no warranty. But hey I was getting a new battery. That Edge must have been a dud, right? Exide Edge--lasted about 5yrs.
4. As a replacement, I got another CT AGM but they had switched OEMs by now so the replacement was a rebranded Deka (East Penn) Intimidator. Well yeah that Exide must have been a dud...right? Well I now had a brand new modern AGM to once and for all prove to myself this would last for years and years. Only FFW to last year when I finally got an electronic load tester (an Anel BA201), and it was showing the battery at like 40% and should be replaced, while only like 3ish years into this battery's life! Well no warranty so load tester must be wrong I'll just keep on trucking since it cranks pretty well. Well FFW to this winter. On the -10C and below days, I can tell it's cranking slowly, can tell it's weak Still don't want to believe it but I know it'll be time for a replacement within another year or so.
On to a week ago now and by accident I left my keys in the ignition since I had to wind down a window for something. I turned the lights off when I did this to avoid battery drain but somehow I totally forgot to turn the ignition off and then went inside my house (car in garage). Wake up next day and realise for the very first time in my life I did something to accidentally drain a car battery! Note that it was not below freezing in my garage that morning, plus being AGM it should be "freeze resistant" anyway due to no free-liquid electrolyte. Anyway I boost it with the trusty Gooloo I got (worked great mind you), and off to work I went. Work is only a 10 min drive so I left the car idling for about an hour so as not to leave it flat in the cold. Luckily it was getting to +1C as it has been the past week so wasn't super cold. Car started up fine that day and actually battery seemed fine for a few days after. On the weekend I put it on my desulfator (a battery minder, so not any high-voltage desulfation). It was there for maybe 8hrs or so and then I went to start the car again. Completely, completely struggled to start, even with full charge. Test it with the electronic tester and now it's showing 200-something CCA. It's done (the Deka Intimidator rebrand)! Three yrs! Done!
Keep in mind when I saw this battery starting to get weak as indicated by the Ancel, I started putting it on a charger/maintainer on weekends whenever I wasn't going anywhere, just to try to make sure I was taking the best care of it. My trips to work are very short and yes that's going to be hard on a battery but 2yrs for a $200ish battery? Also for this reason I never blast the blower motor, almost never use the seat heaters, etc. on trips to/from work--try to keep the loading as low as possible.
Oh and what about that RedTop you ask? Well, it finally gave up the ghost. That one was, TBH, a real champion. I will say that much. This battery outlasted not only its 10yr pro-rated warranty, it outlasted every other lead acid car battery I can remember. The thing is it wasn't constantly in use in any one vehicle, but it was in use for years at a time when it was used. It was actually used in some form or fashion in four different vehicles over the years. However last year when using it to start/move my old car (which has sat in the garage for 10yrs now), it was not up to the task. Keep in mind when the RT was not in use it was on the BatteryMinder, so it was fresh off that but failed to start the car without using a booster pack. So it has finally met its end That guy was great though, I'll definitely give him that much. I actually think it's more the internal contacts at the top of the battery that join the cells and terminals, that have eventually corroded and become no good, more than the cells. There's a YT video of someone cutting open a BlueTop showing this occurring. RIP RedTop, 2004-2020. 16 years!. They don't make you like they used to either though, and you cost over double what you once did!
Anyway in conclusion, what I did now with no warranty on the CT AGM/Intimdator... I was going to buy yet another $220+ "mighty AGM" battery but by now the Kool Aid has worn off, plus they aren't even on shelves at Costblos anymore--have to be ordered. With experience in four different vehicles, four different AGMs, and a lot of money spent on them? Nah not again friends. One out of four...is bad, and certainly not consistent with the "AGM is bestest evar and lasts longer" kool aid they sell you. I bought a Kirkland (JC) flooded battery with 4yr warranty or whatever it is, for $135 instead. This vehicle it's not a trunk-mounted battery so I'm fine with "downgrading" to a flooded battery in this car (you can even use flooded batteries in trunks too but they're not recommended anymore). As a side note the flooded battery is also appreciably lighter than the AGM. So many years of struggling with cumbersome 50lb+ AGMs, a flooded lead acid of the same size seems darn right light in comparison--and who would ever describe lead-acid as lightweight?!
My advice on AGMs now has changed after years with using them and seeing only one last any longer than a traditional battery. During this period the premium over flooded batteries has also skyrocketed for unknown reasons. Economies of scale and widespread-adoption has definitely not kicked in here. Back in the 00s when I bought my YT and RT, they were expensive but they really weren't that much more expensive than "premium" flooded lead acid. Today, good flooded lead acid batts are still typically in the $100-150 range; AGMs OTOH are typically $200+--double the price. And Optimas? LOL Optimas are like $300 now! For 100yr old heavy lead acid stuff. Sure it's the latest tech in lead acid, but even AGM itself is like 30 years old by now, And that expensive tech? Doesn't really buy you any more life or performance TBH. Just a waste of money. I encourage people to not buy AGMs unless they are interior/trunk batteries. There are a lot more of those these days, but if you don't got one there, don't buy AGM.