E53 X5 Battery Options - A List

[E55AMG2]

Originally Posted by X5 Meister

In regard to your first sentence, keep in mind that while AGM's can use any battery charger, the optimal charging voltage and rate is a bit different, strictly speaking, from wet batteries. Just have a look at the CTEK Chargers for example:

http://www.xoutpost.com/bmw-sav-foru...w-one-fyi.html

The US 3300 model has 3 modes essentially. Per the manual:
1. Mode 14.4 V / 0.8 A - This mode is normally used for batteries < 14 Ah. (depicted by the little motorcycle).
2. Mode 14.4 V / 3.3 A - Normal setting for wet batteries, maintenance free and for most Gel batteries. Some gel batteries prefer a slightly lower voltage. Please consult the battery manufacturer when in doubt. (depicted by the little car)
3. Mode 14.7 V/ 3.3 A - This setting is recommended for a battery at temperatures < 41 degrees F. It is also recommended for many AGM batteries like Optima, Maxxima and Odysses. Consult your battery manufacturer when in doubt. (depicted by the little snowflake and sealed battery logo)

I'll invite you along with me to the PRI (performance race industry) show next year. I spoke with the mfgs of all of the above mentioned batteries. Braille, the manufacturer of the battery I linked they told me it's more or less marketing hogwash. All of their batteries (AGM or wet) are designed to be charged anywhere from 12-14.1V (ie the output of an alternator). What's most important is amperage. They told me their car batteries work best when tended at 2A at a minimum of 12V. So long as the charger makes at least 12V and 2A, it wont make one lick of difference. I've owned Optimas and Odysseys as well....all worked perfectly fine with my Die Hard (rebadged schumacher) battery charger at 2A. So unless my charger is magical, Im pretty sure it's just an old wives tale.

The only thing that's voltage critical is when you are trying to code modules or reflash firmware. I'd want a minimum of 12.5V for doing any of that.

[X5 Meister]

You're right about the recoding voltage, BMW specifies a minimum in all their related SIB's.

As far as the old wives tale thing, I believe what you heard, I just don't know if it's completely accurate. All the chargers seem to have their own proprietary formula for optimal charging. Unlike what you heard it's my understanding that AGM batteries apparently prefer higher voltate charge so an option like the Battery Tender Plus which BMW itself sells, and outputs at 12 volts/1.25A, really isn't such a great choice compared to a CTEK charger that outputs 14.7 volts/3.3A in its specific setting for AGM batteries. And hogwash or not, it's interesting to note that the Porsche rebranded CTEK charger does not have a AGM setting since Porsche didn't use AGM batteries and so they didn't want someone to charge at 14.7 volts (I spoke to CTEK about this). Now will both get the job done? Probably. But unless someone did a head-to-head test over the lifespan of the batteries I think it would be impossible to know for sure if one is better than the other. In BMW's SIB on charging they specifically call for the Deutronic charger to be set at 14.8 volts constant voltage while they don't specify the output current. So that's interesting to note as well.

Originally Posted by E55AMG2

I'll invite you along with me to the PRI (performance race industry) show next year. I spoke with the mfgs of all of the above mentioned batteries. Braille, the manufacturer of the battery I linked they told me it's more or less marketing hogwash. All of their batteries (AGM or wet) are designed to be charged anywhere from 12-14.1V (ie the output of an alternator). What's most important is amperage. They told me their car batteries work best when tended at 2A at a minimum of 12V. So long as the charger makes at least 12V and 2A, it wont make one lick of difference. I've owned Optimas and Odysseys as well....all worked perfectly fine with my Die Hard (rebadged schumacher) battery charger at 2A. So unless my charger is magical, Im pretty sure it's just an old wives tale.

The only thing that's voltage critical is when you are trying to code modules or reflash firmware. I'd want a minimum of 12.5V for doing any of that.

[E55AMG2]

Originally Posted by X5 Meister

You're right about the recoding voltage, BMW specifies a minimum in all their related SIB's.

As far as the old wives tale thing, I believe what you heard, I just don't know if it's completely accurate. All the chargers seem to have their own proprietary formula for optimal charging. Unlike what you heard it's my understanding that AGM batteries apparently prefer higher voltate charge so an option like the Battery Tender Plus which BMW itself sells, and outputs at 12 volts/1.25A, really isn't such a great choice compared to a CTEK charger that outputs 14.7 volts/3.3A in its specific setting for AGM batteries. And hogwash or not, it's interesting to note that the Porsche rebranded CTEK charger does not have a AGM setting since Porsche didn't use AGM batteries and so they didn't want someone to charge at 14.7 volts (I spoke to CTEK about this). Now will both get the job done? Probably. But unless someone did a head-to-head test over the lifespan of the batteries I think it would be impossible to know for sure if one is better than the other. In BMW's SIB on charging they specifically call for the Deutronic charger to be set at 14.8 volts constant voltage while they don't specify the output current. So that's interesting to note as well.

My point was the differences between the two are inconsequential. You can use either the CTEK or any other quality charger and the performance of the battery will be the exact same. The key here being quality, so long as that exists you absolutely DO NOT need a special charger for an AGM battery. Would it be nice to have, sure...but its not necessary in any capacity.

WRT Porsche, BMW AFAIK does not use AGM batteries either. At least none that I've personally laid eyes on. The 1.25A tender they sell is a joke, as the amperage really isnt sufficient to prevent Sulphation. So far as I know, 2A is the minimum to reverse the sulphation process. Also the Deutronic chargers are designed to maintain a relatively high specific voltage, and vary amperage as needed for coding/diag. Black and Decker also makes units that do this. Does that mean they're any better for simply charging/maintaining a battery on a car that sits in storage? No, not really.