Yeah, I had to dig to find it, and posted the updated address. I edited my above post.

Like I said I wouldn't get too spooled up about it, those numbers are temperature dependent too.

Most batteries AGM or not, are chronically starved anyway. Batteries CAN be overcharged but it takes real dedication.

 

Must have just missed the update - wasn't there when I read the post (and it was a quick dig on the Qdyssey site).

I also run the rebranded Odyssey batteries (Diehard Platinums - and love them), and it doesn't really bother me, but when a person pays $500 + for two batteries, then I can see why it is worth considering ..............

 

It's a tough thing, though - want solid batteries, not excited to pay dramatically more for them but do anyway, and then are slapped with a notion backed by the manufacturer that the warranty is in jeopardy and the batteries life will be shortened by most properly-sized alternators as most are regulated at 14.9 - simply too high, even if only by 'a little'.

Then again, most 6.0's have dramatically under-sized alternators that result in a near continued chronically under-charged set of batteries that'll never see the 14.9 charge rate regardless of temperature anyway.

Neither 'extreme' is awesome.

I'd suggest to folks considering the AGM's to do so only if they are willing to shell out for a properly regulated alternator. If not, use a less spendy but still properly sized alternator and stay with the wet cells.

I can't find anything documented online to back this up anywhere, but I've heard rumors from a few different places that the days of wet cells are numbered - essentially that in five'ish years we won't be able to get them.

Maybe someone else has heard the same? I sure hate spreading rumors if they aren't substantiated. I wouldn't base any new alternator choice on an inability to pick up wet cells in the future just yet, though would think twice about which alternator to go with if I liked the notion of going the AGM route in the future.

 

14.9 sounds high for wet lead acid batteries, which is what is in most trucks. I shoot for 13.8-14.2 in all my vehicles. I have an Odyssey PC680 in the airplane and I just put it on a maintainer made for AGM batteries every 3 months or so to keep it healthy.

Sams has a Duracell AGM for under $170

 

It's a bummer that the Sams Duracell AGM is only 750CCA though.

 

14.2 is actually a little low depending on the type of battery, many batteries are "maintenance free" these days, although they are technically wet lead acid batteries.

But the charging voltages are different (higher) than a classic flooded wet cell. Charging voltages are based in part by the OCV of the cells. A modern "maintenance free" battery is fully charged at 12.84 volts, a couple tenths doesn't sound like much but it is.

Generally it takes approx. two (2) volts above the OCV before a battery starts approaching full charge, and then this is held for a period of hours.

 

Here is a "warning" message from a manufacturer of high output alternators (I wonder what other high output alternator manufacturers say):

"Anyone, Installing / Maintaining or Testing AGM Batteries must read the Battery Manufacturers instructions prior to handling any AGM batteries. K.E.I. has researched the internet on this matter, and although these batteries have some outstanding features, K.E.I. Alternators have a voidable warranty, on any vehicle that uses ours products, if AGM batteries are in use. Serious damage, as well as physical harm can result from the improper use of AGM batteries! Again, the document below is just a caution, we don't want anything negative to happen from the use of AGM Batteries.

1. When using AGM Batteries, you must "Only" use the exact same model, Manufacturer, when muiltiple batteries are installed, "NO" exceptions allowed!


2. AGM Batteries are absolutly not to be installed in the engine compartment. AGM Batteries don't work properly in a High-Heat enviroment!


3. AGM Battery Manufacturers recommend halting charge when the battery core reaches 49 Degrees Celcius or 120 Degrees Farenhight!


4. AGM Batteries have .000002 ohms of resistance. This can cause the charging system/Alternator to be at Max Output continuously!


5. Maintenance personnel must be knowledgable & trained about how to maintain and charge AGM Batteries!


6. All charging cables must be upgraded , both Positive & Negative, to Alternator Manufacturers specifications!


7. K.E.I.'s Warranty Policy makes the use of AGM Batteries a voidable, by K.E.I. , warranty situation!

K.E.I. highly recommends considering a different type of battery.

K.E.I. Notes
We have reviewed many AGM Battery Manufacturers Web-Sites. The above information is consistent across all brands we reviewed. Be sure to review the Battery Manufacturers guidelines, it's critical to do this, not doing it could cause bodily harm, fire, melting of cables and connections, and premature alternator failure!"

Caution-AGM-Batteries

 

Mark,
That looks like some serious butt covering. I'd like to know the source of their "internet research". I've had Odyssey batteries in my airplane for 10 years and not experienced any problems and it's mounted to the firewall, 12" behind the exhaust stacks. I'm on my second only because the charger I was using went haywire and the voltage went to 15.5 volts. The alternator and regulator are basically motorcraft 70's vintage with the exception of price. The Odyssey likes 14.5-14.7 to charge but will charge at lower voltages, it just takes longer. Higher voltage is the problem as they get hot quick and that ruins the battery.

Here is the tech notes we used when we did our research for using them.

http://www.odysseybattery.com/docume...M-002_1214.pdf

 

I've got two Of the Sears Diehard Platinum batteries in my Dodge that were purchased in 2010. Seem to be doing fine, with no upgrades to the charging system. I recently went to the Sears website, looking to purchase some for the Excursion, only to find that they were no longer selling them. I paid >$200 a piece at the time, I wonder if anyone else is selling the re-branded Odysseys?

 

I find the #2 warning interesting and I can find no such warning on odyssey's web site stating they should not be installed in the engine compartment.

 

It sure is!! Surprised me when I saw it.

Thanks for the post and the link!

Almost 3 years on mine now. Still going good!

 

Man, I need to go back to battery school.

 

lol Jack!

GM and Tesla are in the news about new / developing battery technology (Yahoo Finance)! Good stuff I guess.

 

I guess based on above I need to spend more time reading on the AGMs. I'm still a guy who likes to pull spec grav on each cell every late fall.

I've followed Telsa in the financial news trying to determine if I want to invest in that company - P/E is way out of my normal comfort range, well for my age.

 

you and me both! I will say though - it seems like P/E doesn't influence or indicate stock "value potential" nearly as much as it used to (I am still uncomfortable with that).