Sears Diehard Platinum AGM

[RitcheyRch]

I had a Sears Diehard Platinum (Made by EnerSys Energy Products) for 10 years in my old 4Runner. It sat a lot. When I sold the 4Runner, the battery still cranked the engine like the battery was new.

Wish they were still made by EnerSys (Odyssey)

 

[f355spider]

I have never had a problem with AGM batteries in older cars...1978 Ferrari 308GTS, 2001 BMW 540, etc. Lasted for many, many years without issue. Also strange about the Sears Platinum AGM failures so early. Granted Sears uses many vendors, but around 2012 or there about they were made by Odyssey...and were super high quality and much less expensive than buying them from Odyssey directly.
I actually put one of those in my 1997 Ferrari 355 Spider. It was terrific

 

[Carlostrece]

Die hards have generally been a very solid battery choice. When under the Sears banner, they were made by Johnson Control until about 2019 when Clarios acquired their Power Solutions division and started manufacturing batteries under several brand names. Advance Auto Parts bought the brand name and still sells Die Hards, AGM and conventional flooded ones. Early AGMs under AAP ownership were built in Germany by Varta. I know, because the one in my Passat has the "Manufactured by Varta" and "Made in Germany" stickers underneath the Die Hard decals. Now they are made in Mexico for US consumption. Either way, still a very good choice for a battery. Mine is almost 4 years old and still kicking strong.

That said, my car also has the charging system protocol for that type battery and does lend to the best life expectancy for an AGM. If your car doesn't have an optimized charging protocol for an AGM, it could give shorter battery life for that type. Heard many instances of it, but also many instances where the AGM lasts longer in those systems than flooded cell conventionals. Guess its just a luck of the draw.

I don't think it's luck. I think (guessing) it's how a person uses their old car with an AGM that matters. I'm refering to old cars that have a charging profile for flooded batteries.

If the old car sits in storage in a garage a lot (at temps above freezing) then AGM probably would last longer, especially if using a trickle charger. The cars charging profile wouldn't matter much and so AGM is better than flooded.

However, if the car is driven a lot, then the car's charging profile matters, IMO. Especially if the car is parked outdoors in winter conditions and started and driven in cold weather. Then the car's charging profile matters a lot and flooded is better.

Those are the conclusions I've reached based on my past experiences combined with info others posted in this thread.