I prefer AGM

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regular....

 

Decaf.....lol

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AGM also last a lot longer. I'm almost at year 8 on a 5 year warranted AGM battery and it still starts the car after sitting for weeks at a time.

I started buying AGM about 12 years ago and I'll never go back. It's basically the tech that made Optima batteries so great when they first came out and were patented.

 

LOL !!! good one

 

I have AGM on both of my cars, the oldest one is 2 years old and no problems so far.


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Dang...I paid the dealer well over $300 to replace a battery that was only weeks out of warranty. I can't imagine what the price of the more expensive one would be!

 

The battery for my C70 cost me $235 at O'Reilly auto parts. It is a 94R AGM (for premium audio vehicles)

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AGM's do have some nice advantages. However, they do behave a little different than lead acid batteries. They have a little different voltage profile and charging requirements. The in-car charging system is fine. However, if you need to use a battery charger then you want to get one that has a mode for AGM. Many regular chargers will charge them ok but not ideal. Some non-AGM smart chargers will erroneously detect charge cut-off too early and won't charge the AGM battery. I found this out first hand.

A bad car alternator can damage an AGM battery. I found this out first hand. The voltages looked good during and after charging but the voltage would drop to 10V over 24 hours. There were no abnormal parasitic loads. The battery tester at Advance Auto Parts said the battery was good but needed charging. It was only after I let them charge the battery for 2 hours and the tester still said it was good but needed charging that it was determined bad. A tester needs to have an AGM mode to properly test the AGM battery.

 

There are a bunch of options but here is what I've used for the last 4 years.

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Only 2+ Years???!!!!! I’ll never buy a genuine battery then. Heck no!


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Only 2+ Years???!!!!! I'll never buy a genuine battery then. Heck no!

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I've had a few replaced under S&S or warranty. Trying to remember if any one batt lasted more than 3 years(our usual trade-in age). MAYBE the one in our '04 ragtop.

 

I've had good luck with AGMs in several cars over the years (mostly red Optima batteries), and my C70 is on its second AutoZone Duralast H7 AGM (~$200). The car is nearing 10 years old and I'm on my third battery... three years has been the average duration - clearly there are a lot of devices using the battery with the ignition off. For sure, I'm partly responsible given the SmartTop and Volvotech VBB4 rear camera I put in (both of which draw a tiny amount of current all the time), but there are plenty other small current vampires in the car straight from the factory.

Based on my experience, the AGMs have not outlasted the conventional factory battery. The factory battery failed after just over 4 years and I put in a Duralast AGM, which was then replaced after about 35 months under AutoZone's full 36-month replacement warranty. The first Duralast AGM did not fully fail but the voltage was dropping below 12V, which created problems with my VBB4 rear backup camera (the voltage drops requires the VBB4 to be reset, which is a real pain). I was also gettng the random issue of the window up/down not working when the doors are opened/closed. While I'm happy that AutoZone honored the warranty, they were clear that the next one is on me.

Not sure if I'd buy an AGM for the C70 again but I figure I have at least 18 months before I have to do something. I seldom drive the C70 these days (since the pandemic began) and I have the car on a trickle charger, so we'll see what happens.

 

Thanks Regtor - I can always count on you for a succinct and well thought out comment. Yeah well-I think I'll just go for the regular one. Costco has Interstate ones and they have a 3 yr. warranty.
My S40 OEM one went exactly at 5 years. Replaced by a DieHard in 2015. I have a Toyota pick up and bought a Duralast one 12 years ago- go figure. I couldn't believe it when I replaced it 4 months ago. I also had 2 Duralasts in my Vanagon in 4 years. The C70 has an OEM replaced 4 years ago. Ya know I'm getting to believe it's like buying fruit- always a gamble. Side note: I don't really have a big carbon footprint- with all the vehicles I do like 16,000 miles per year-combined. At least before this year anyway.

 

One thing to consider, I recommend getting a good battery charger/smart charger with at least a 10Amp output. Twice a year, minimum, disconnect it from the car and put it on a charger and let it run for a few hours or until it says full.

Depending on vehicle use, the battery will slowly drop to a lower SoC (state of charge). This is when sulfation happens and starts degrading the battery. Keeping a batteries SoC close to 90% helps reduce issues.

AGMs are good, like previously posted, have a slightly different charge requirement, but a good smart charger will have the AGM feature.

Top it off a few times a year can significantly increase battery life.

~T