Why not go with an AGM Battery?

[PiperOne]

Depending on how "smart" your charging system is it may compensate and be fine with an AGM. I run them in all our stuff and the non ECM controlled GM alt's reliably push out 14.7 V at 70F and temp compensate enough that we have no issues. I really notice the difference on the vehicles that do a lot of stop and start or have other high cycling needs..the AGM just lasts and lasts...totally worth the extra cost. We use an off brand from Freightliner made by Deka/East Penn.

 

[ZZman]

Interesting link on charging AGM batteries.

http://www.hotrod.com/articles/hrdp-1009-how-to-charge-a-agm-battery/

 

[Quattro Pete]

Originally Posted By: ZZman
How does the charging deference relate to chargers? Wouldn't they still use a 12 volt charger? Aren't the amps a big factor?

The actual charging voltage is not 12V. More advanced chargers have a separate setting for charging AGM batteries which modifies charging voltage a bit.

The actual current/voltage curve will depend on the specific charging logic that a given charger employs.

 

[JHZR2]

Originally Posted By: SubLGT
Originally Posted By: Rand
..Agm batteries want slightly higher voltage. If your car is designed for AGM its better...


Some AGM batteries require less voltage:

Quote:
...John Munsell, battery product specialist for General Motor Corp.’s ACDelco brand, says the key for shops will be training to diagnose and repair start-stop vehicles…...Munsell says AGM batteries require special care when charged offline. “This special care is to make sure that the charger has an AGM switch that will supply lower voltage to the battery during the charging process. This lower voltage is required due to the charge receptivity of AGM batteries. The maximum charging voltage for an AGM battery at 80 degrees Fahrenheit is between 14.4 volts and 14.6 volts. If the ambient temperature is higher than that, charging voltage goes down,” says Munsell…

...Munsell says that for vehicles manufactured by General Motors, “we neither recommend, nor endorse replacing an AGM battery with an EFB [enhanced flooded battery] battery. An EFB battery will have a different charge profile than an AGM battery, which will lead to premature failure of the battery.”


http://www.moderntiredealer.com/article/722503/prepare-now-for-start-stop-systems


Going too high can do two things, either drive excess current (don't needs huge voltage over potential to drive current into low impedance), and also can drive electrolysis, beyond some point the AGM can't recombine fast enough.

 

[Virtus_Probi]

Originally Posted By: Reddy45
If AGM is good then why not get a lithium car battery?

http://www.jegs.com/p/Lithium-Pros/Lithium-Pros-12-Volt-Lithium-Batteries/1770167/10002/-1

(Talk about sticker shock!)


Those things must have some VERY fancy protection circuits as Li-ion cells can be very dangerous if they are charged above 4.1/4.2V depending upon the type (think the 4.2V version is dominant in the market), I'd assume they use parallel arrangements of 3 cells in series to make close to 12V. I worked on a charger for those suckers a while ago and the very precise 4.1V/4.2V topoff threshold was a critical spec and the charging current approaching that threshold had to be ramped down just so.

There was a company called Ohm promising a light car "battery" using supercapacitor technology and some kind of smaller lithium battery for backup charging, signed up for updates from them years ago and they never sent my anything so I guess they are making vaporware.

I was thinking about AGM for my latest battery purchase and dropped that idea fast after poking around and finding they aren't necessarily drop in replacements for lead-acid types...didn't seem worth the possibility of any trouble.

 

[Errtt]

I put a AGM in the wife's Lexus RX330, they had it in size.
It's been less than a year but haven't seen any issues.
She doesn't use the Lexus much, sometimes it sits a week, sometimes longer. It might get less than 1k on the clock in a year depending how much I take it out for a spin up/down a highway run. She just runs it in town to a store or whatever once in a while.
Just dropped the AGM in place & did nothing else system wise. Previous battery was lead acid.

 

[PiperOne]

I learned (the expensive way) that AGM's do need to be charged right. They like 14.7V..and lots of amps if they get drained. Float charge setting around 13.8V. In applications where we have onboard inverter/chargers and 4 grp 31 AGMs the charging sequence is bulk charge (full amps from the charger) until 14.7V is reached, an absorption charge (a constant 14.7V with declining amperage..and the charger limits this time based on how long it took to bulk charge..and then it floats at 13.8V). In a very high cycling deep discharge usage I can get 4 years out of a set of batteries. Our original chargers and vehicles stopped at 14.3V...6 month lifespan. The company that makes our 12V no idle A/C units (they recommend Odyssey's) is a big believer (and they tested it) in very high current charging. When they put a unit in a highway truck for example..they usually install an alternator north of 300 amps.

 

[dogememe]

I currently have regular, non-AGM batteries in both of my vehicles. When those go (which will be a while, since they're pretty new, but they were not purchased by me so no warranty), I'm going AGM. On the Suburban that's easy, but for the Escape, I might not be able to do that easily.

 

[Chris142]

Originally Posted By: john_pifer
Originally Posted By: Chris142
I like them. They dont corrode the terminals like a flooded battery does.


Easily prevented by applying grease to protect the cable terminals.
Still corrodes.

 

[SHOZ]

AGM batteries are sealed better for obvious reasons. Cheap US made batteries have poor post to top seals. Grease may slow corrosion, but the corrosion is coming from acid leaking out at the post.

Overfilling and rough handling are also two big reasons.

 

[Kira]

Are AGM compatible battery chargers on the market yet?

 

[Quattro Pete]

Originally Posted By: Kira
Are AGM compatible battery chargers on the market yet?

Yes, and they have been for quite some time. AGM is not new.

 

[RitcheyRch]

Just bought this charger a few weeks ago and have yet to use it.

Originally Posted By: Quattro Pete
Originally Posted By: Kira
Are AGM compatible battery chargers on the market yet?

Yes, and they have been for quite some time. AGM is not new.

 

[SHOZ]

I don't have any issue charging AGMs with my 30 year old 2A/6A charger. I have brought them back from the dead but it takes about a week.

 

[barryh]

You don't want to overcharge an AGM as eventually it will vent electrolyte which can't then be replaced. An unregulated charger would need careful voltage monitoring. I have an old regulated charger and have adjusted a pot inside to raise the voltage for an AGM.

 

[SHOZ]

Mine peaked at 15.3v.

They have to build up enough pressure before they vent, around 10 psi back in the day.

 

[Panzerman]

$$$ and not significant enough performance to warrant the extra $$$.
Now in ATVs and Motorcycles- Yes. They don't have a real charging system and they sit more but for the average car it would be alot more cost for a little more performance.

 

[Duffyjr]

This is from the my Ctek 4.3 manual. I realize it's a couple three years old but it has "many AGM batteries" under Normal (14.4) and "power AGM batteries like Optima and Odyssey" (14.7). So how is one suppose to know which setting to use.

 

[CharlieBauer]

Originally Posted By: Duffyjr
This is from the my Ctek 4.3 manual. I realize it's a couple three years old but it has "many AGM batteries" under Normal (14.4) and "power AGM batteries like Optima and Odyssey" (14.7). So how is one suppose to know which setting to use.


Normal 14.4v for the everyday cheaper standard sized drop in replacement AGM's eg diehard, autozone, bosch from pepboys, carquest / aap, walmart etc.

AGM setting 14.7v for the original style more expensive Optima and Odyssey AGM batteries.

 

[CharlieBauer]

Originally Posted By: rooflessVW
East Penn AGM (NAPA's "The Legend) is what I always buy.

Factory Varta AGM in the Phaeton is at 13 years and still going strong.


The factory installed non AGM Vartas also last a long time. Most reports I've seen indicate 7 years is the minimum and 10 to 11 years is possible, even under the hood. Mine, under the hood, lasted 7 years and was very neglected throughout that period. In fact, it failed not soon after I started maintaining it!

Is the Phaeton's AGM located in the car / trunk?

I believe that design wise, the made in Europe Varta AGMs are identical to the various JCI manufactured AGMs sold in AAP etc. But the ultimate quality may well be different as has apparently been the case with different JCI manufacturing sites.