RunningTooHot and shertex - Thanks for your input !

__________________
Marshall Welch
Seattle, WA
1982 300D-T

Thanx Marshal ! .

When I lost a battery in Indio, Ca. it was 108* and the Autozone didn't have any correct sized battery so I motored on down the road stopping in at every partshaus until I found the correct one @ Walmart of all places .

I'd leave the car parked and idling with SWMBO inside it .

I didn't dare turn it off until I had a new battery .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Thanks Shertex – it seems very likely that you are right! I was working from memory, and I may have been mixing up concerns which could be valid for gel cell batteries rather than AGM. It sort of makes sense; when a bubble forms in gelled material, it’s not going anywhere, whereas a saturated fiberglass mat in an AGM battery may allow the gas to move up (and out) while wicking electrolyte into the voided space. (Hypothesizing here, but it seems logical.)

That being said, your contact at C-Tek confirms that there is no benefit to running the desulfation program on an AGM battery, so it seems prudent to avoid doing so.

Either way, AGM batteries are more sensitive to charging conditions, as well as peak & float voltages. Here is an interesting article. (In fact, the entire site is quite informative) Of particular interest is paragraph 7:
https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm (It sure would be nice if we could adjust the voltage regulators built into the brush assemblies on our alternators. )

Another interesting article on general principles of charging lead-acid batteries:
https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

I hope this information may be helpful, both now and in the future...

__________________
Current rolling stock:
2001 E55 183,000+ Newest member of the fleet.
2002 E320 83,000 - The "cream-puff"!
1992 500E 217,000+
1995 E300D 412,000+
1998 E300D 155,000+
2001 E320 227,000+
2001 E320 Wagon, 177,000+

Prior MBZ’s:
1952 220 Cab A
1966 300SE
1971 280SE
1973 350SLC (euro)
1980 450SLC
1980 450SLC (#2)
1978 450SLC 5.0
1984 300D ~243,000 & fondly remembered
1993 500E - sorely missed.
1975 VW Scirocco w/ slightly de-tuned Super-Vee engine - Sold after 30+ years.

OK, purchased a CTEK battery charger and it is charging the 12 volt AGM battery right now. I have this Stanley jump starter (see photo) and it needs to be charged. normally it will charge up after a few hours by attaching an extension cord to an outlet. I purchased a six foot heavy duty extension cord and yet the unit will still not charge.

So....I'm thinking of using the new CTEK battery charger (model 7002) to charge it up. I will need to remove the battery from the unit to do it, however. Notice: the CTEK user manual says to only use it for charging lead-acid batteries and to not use it for charging dry-cell batteries. Any possibility this Stanley unit could be dry-cell?

Attached Thumbnails

 

It is a lead acid battery, now I have to figure out how to remove the cover to get to the battery so it can be rejuvenated.....

Depends very much on the vehicle. Batteries don't like high heat or vibration. AGM batteries especially don't like the heat.

In w210 with the battery under the back seat, it is pretty well insulated and protected, getting 10 years out of a w210 battery is not unusual at all. As a data point, I once owned a '97 w210 that I bought used. I owned the car for 10 years exactly before selling it. I never replaced the battery - whatever was in it at purchase was still going strong when I sold the car 10 years later.

In w123 with battery sitting inches from the scorching hot turbo and exhaust manifold, I would not expect batteries to have a long life. AGM would be a poor choice in w123.

As for charging, any of the modern "smart" chargers are designed to accommodate multiple chemistry types including AGM.

__________________
Current fleet:
1998 E300 turbodiesel
2008 E320 bluetec - leaky oil cooler seals replaced
2012 S350 bluetec
2014 GL350 bluetec

Sold:
1996 Passat TDI
1997 E300 diesel

Thank you Sir ! .

I once saw a new VW with a factory insulating blanket around it's under hood battery, said battery failed after 1 year .

I'm wondering why husky man needs to open the battery to charge it.....? .

It must have some sort of connections already .

One of my Motocycles (2000 Kawasaki W650) came with a sealed AGM battery .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

To back up Mike D's knowledge,
I found this while looking at info on a Lexus forum ( researching switching to Lexus ):

ABSORBED GLASS MAT (AGM) BATTERY INFORMATION – SS006-07 August 11, 2007
Page 2 of 3
Differences between AGM and flooded lead acid batteries:
􀀀 AGM batteries have thin, sponge–like, glass mat separators that absorb all
liquid electrolytes.
􀀀 Flooded lead acid batteries have free, liquid electrolyte all around the plates
and separators.
􀀀 Flooded lead acid batteries can easily release gas that is formed during a charge,
while AGM battery life is diminished if gas is formed during charging.
Similarities between AGM and flooded lead acid batteries:
􀀀 Both share the exact same lead acid chemistry.
􀀀 Both share the same charge and discharge principles.
􀀀 Both are safely charged by vehicle charging systems.
􀀀 When discharged, both can be recharged at high current levels.
Damage to AGM batteries becomes an issue when the charge rate is NOT monitored
and controlled by the charger (i.e., quick chargers). The performance of an AGM battery
can be irreversibly reduced if the charge rate remains too high, allowing the battery to
overheat and vent. Once an AGM battery loses water (venting), the glass mats will
become dry, causing the battery to lose conductance, power, and performance.
In most vehicle charging systems, the alternator limits the charging rate by limiting the
output voltage (about 14.4V). For example, an AGM battery may be observed charging at
60A and 13.5V. As the battery recharges, the charging voltage will increase from
13.5V to approximately 14.4V (voltage will vary based on temperature, control
sophistication, etc.), and the current will decrease from 60A to about 0A. The charging
system voltage regulators prevent both AGM and flooded lead acid batteries from being
overcharged and venting. By controlling the voltage, the charging rate (current) can
be controlled.