The AGM Battery

[Gelbster]

Except in some special situations?
"The leading advantages of AGM are a charge that is up to five times faster than the flooded version, and the ability to deep cycle. AGM offers a depth-of-discharge of 80 percent; the flooded, on the other hand, is specified at 50 percent DoD to attain the same cycle life. The negatives are slightly lower specific energy and higher manufacturing costs than the flooded."
Absorbent Glass Mat (AGM) Battery Information - Battery University

[10/10ths]

If they are over rated, then why do OEMs invest in AGM batteries in their Auto Stop/Start versions of their cars?

If they didn't work better, they wouldn't spend the money to put them in those vehicles.

I bought this one:

NSB-AGM 94R/L4

I keep it alive with this:

CTEK Multi US 7002 - CTEK Battery ChargersCTEK Battery Chargers

Two years in, so far, so good. Car sits a lot.

Good luck.

[PaulE]

Originally Posted by 10/10ths

If they are over rated, then why do OEMs invest in AGM batteries in their Auto Stop/Start versions of their cars?

If they didn't work better, they wouldn't spend the money to put them in those vehicles.

I bought this one:

NSB-AGM 94R/L4

I keep it alive with this:

CTEK Multi US 7002 - CTEK Battery ChargersCTEK Battery Chargers

Two years in, so far, so good. Car sits a lot.

Good luck.

Maybe it's just overkill for an older car without auto start/stop? I am only on my second battery in my 03 S, it is an Interstate that I put in in 2009 to replace the original battery. I use the older version of that CTEK - same as the one Porsche sold at dealerships but without the "Porsche" label and premium pricing. If I can get this long out of a traditional battery (OEM -6 years, Interstate - 7 years and still kicking), what's the benefit of AGM to me?

Now that I've said that, my Boxster has been out at the body shop for a week, and then goes back to my independent garage for installation of the sport suspension. With the car off the battery tender for that long, I may have just cursed my battery!

[Gelbster]

Cursed ?
No
It is just chemistry. If the SOH is 50% or less but it still takes at least 90% charge, try to desulphating it. That is the specific problem that causes most lead+acid batteries to fail.

[particlewave]

Originally Posted by 10/10ths

If they are over rated, then why do OEMs invest in AGM batteries in their Auto Stop/Start versions of their cars?

If they didn't work better, they wouldn't spend the money to put them in those vehicles.

The 986 is not a stop/start vehicle. It's also not a hybrid or electric vehicle. AGM is overrated and your statement is a prime example of that.
When was the last time you made an AGM battery? I worked for Johndon Controls for years, so take my word for it. They are a waste of money in most cars.

[10/10ths]

...I don't understand.

How was my post an example?

[911monty]

Originally Posted by particlewave

The 986 is not a stop/start vehicle. It's also not a hybrid or electric vehicle. AGM is overrated and your statement is a prime example of that.
When was the last time you made an AGM battery? I worked for Johndon Controls for years, so take my word for it. They are a waste of money in most cars.

Well Particle I have a question then. Isn't a prime advantage of the AGM is that it doesn't outgas as much? Doesn't this help to prevent corrosion on terminals and lessen gasses in the enclosed frunk?

[Gelbster]

That is why there is a vent hose on the car. Otherwise ,yes.

[911monty]

Originally Posted by Gelbster

That is why there is a vent hose on the car. Otherwise ,yes.

I understand and this is specific to the boxster, however the statement was that it is overkill for most cars. The lack of a vent and corrosion on terminals on most other cars makes this a highly valuable feature. I'm a fan of additional protection and don't like to see corroded terminals on any car I own.