[808MGuy]

Originally Posted by tom @ eas

AGM type batteries have a 5-7 year lifespan, most will not even have their BMWs this long, if a battery is replaced and never registered - the alternator will pump full current to the battery thinking the lifespan has reached its point - cooking the battery to death.

A replacement battery will be much more expensive than a simple registration session.



http://en.wikipedia.org/wiki/VRLA_battery

I have never heard of any charging system in older cars that would overcharge an AGM battery. I had an Odyssey AGM in my last car and there was no such procedure to go through. In fact, most automotive batteries don't like quick charging so it wouldn't make sense for the alternator to try to pump full current into the battery for faster charging and then ramp down once its charged. Its typically better to trickle charge them to avoid overheating.

Isn't the computer interface related to the battery associated with the regenerative braking feature where the alternator charges the battery when the car decelerates? I thought this feature wasn't available in the US. In this scenario, I can see the need for computer intervention since the computer needs to know what the battery level is and when the car is decelerating but otherwise, it just doesn't make any sense.

[tom @ eas]

Originally Posted by 808MGuy

I have never heard of any charging system in older cars that would overcharge an AGM battery. I had an Odyssey AGM in my last car and there was no such procedure to go through. In fact, most automotive batteries don't like quick charging so it wouldn't make sense for the alternator to try to pump full current into the battery for faster charging and then ramp down once its charged. Its typically better to trickle charge them to avoid overheating.

Isn't the computer interface related to the battery associated with the regenerative braking feature where the alternator charges the battery when the car decelerates? I thought this feature wasn't available in the US. In this scenario, I can see the need for computer intervention since the computer needs to know what the battery level is and when the car is decelerating but otherwise, it just doesn't make any sense.

I've been wanting to post a tech article about this subject for some time, might as well start now:

Absorbent Glass Matt Battery (AGM)

In contrast to conventional lead-calcium batteries, the sulfuric acid in an AGM battery is not held freely in the battery housing. The sulfuric acid is instead entirely bound into the mats of the glass-fiber fleece. For this reason , no acid can escape if the battery housing is damaged. In addition, the AGM battery is a sealed, airtight unit. This is possible because the gasses are converted back into water by the permeability of the separators.

Construction
AGM batteries differ from conventional lead-calcium batteries in the following points:

- Larger plates which allow a power density some 25% greater
- Glass-fiber-fleece separators which enable a cycle consistency up to 3x greater improving cold-starting ability, current consumption and service life
- Airtight housing with pressure relief valve
- Inspection plugs sealed and cannot be opened
- Acid bound in glass-fiber fleece

How AGM Batteries Work
AGM batteries differ from conventional lead-calcium batteries in their environmental compatibility and their retention of gases during charging. When a vehicle battery is charged, the electrolysis process emits the gases oxygen and hydrogen . In a conventional lead-calcium battery, these two gases are released into the atmosphere. In an AGM battery, the two gases are converted back into water: The oxygen created at the positive electrode during charging moves through the permeable glass-fiber fleece to the negative electrode, where it reacts with the hydrogen ions that are brought in with the electrolyte, to create water (oxygen cycle). In this manner, the gases, and thus the electrolyte, is not lost.

Only when the gas production is excessive, that is when too much pressure is generated (20 to 200 mbar), does the pressure-relief valve open, thereby allowing gas to escape while also preventing entry of atmospheric oxygen. Because the pressure in the battery is regulated by a valve, the AGM battery is also known as the VRLA battery (valve regulated lead acid).

Service Instructions for AGM Batteries
When handling AGM batteries, certain special factors must be taken into consideration with regard to battery renewal and installation location:

Do not charge AGM batteries with 14.8 volts or use use rapid charging programs
When charging batteries in the "stand alone" mode, the maximum charge voltage of 14.8 volts must not be exceeded. Even briefly charging an AGM battery with a charge voltage of more than 14.8 volts (voltages usually used in rapid charge programs) will damage the battery

Do not install AGM batteries in the engine compartment
Because of large temperature variations, AGM batteries must not be installed in the engine compartment. This would result in a significant reduction in the service life of the battery

Do not open AGM batteries
By no account should AGM batteries ever be opened, as oxygen from the atmosphere would cause the battery to lose its chemical balance and cause it to fail.

Battery Replacement
An AGM battery, when installed as original equipment, must always be replaced with an AGM battery. In special cases, where a customer's driving profile (e.g. short distance driving), results in a discharged battery, the AGM battery is a recommended replacement.

Note that replacement batteries resulting from a customer's driving profile cannot be claimed under warranty.

Battery Replacement Registration

This Service Function informs the PM that the battery has been replaced. It completes the following operations:

- Battery capacity is set to 80%
- Current Odometer reading are stored. The odometer readings at which the last seven battery replacements took place can be read off from the Diagnosis Requests of Control Unit Functions
- Stored battery statistics (current, voltage , battery charge level) are deleted
- Stored temperature statistics are deleted

Hope this helps.

[SMOKE EM IF U GOT EM!!]

Originally Posted by chemgeek

I am assuming that the battery is covered under the 4 year maintenance contract?? If so, then you could drive the car for 6 years without even having to worry about it.

asswipes at my dealer told me its a normal wear and tear item and they couldnt warranty it, which i know is bullshit.

[fullrev]

Originally Posted by SMOKE EM IF U GOT EM!!

asswipes at my dealer told me its a normal wear and tear item and they couldnt warranty it, which i know is bullshit.

batteries aren't covered under CPO warranty or maintenance.

they are only covered under the new vehicle warranty.

[fullrev]

Originally Posted by tom @ eas

I've been wanting to post a tech article about this subject for some time, might as well start now:

Absorbent Glass Matt Battery (AGM)

In contrast to conventional lead-calcium batteries, the sulfuric acid in an AGM battery is not held freely in the battery housing. The sulfuric acid is instead entirely bound into the mats of the glass-fiber fleece. For this reason , no acid can escape if the battery housing is damaged. In addition, the AGM battery is a sealed, airtight unit. This is possible because the gasses are converted back into water by the permeability of the separators.

Construction
AGM batteries differ from conventional lead-calcium batteries in the following points:

- Larger plates which allow a power density some 25% greater
- Glass-fiber-fleece separators which enable a cycle consistency up to 3x greater improving cold-starting ability, current consumption and service life
- Airtight housing with pressure relief valve
- Inspection plugs sealed and cannot be opened
- Acid bound in glass-fiber fleece

How AGM Batteries Work
AGM batteries differ from conventional lead-calcium batteries in their environmental compatibility and their retention of gases during charging. When a vehicle battery is charged, the electrolysis process emits the gases oxygen and hydrogen . In a conventional lead-calcium battery, these two gases are released into the atmosphere. In an AGM battery, the two gases are converted back into water: The oxygen created at the positive electrode during charging moves through the permeable glass-fiber fleece to the negative electrode, where it reacts with the hydrogen ions that are brought in with the electrolyte, to create water (oxygen cycle). In this manner, the gases, and thus the electrolyte, is not lost.

Only when the gas production is excessive, that is when too much pressure is generated (20 to 200 mbar), does the pressure-relief valve open, thereby allowing gas to escape while also preventing entry of atmospheric oxygen. Because the pressure in the battery is regulated by a valve, the AGM battery is also known as the VRLA battery (valve regulated lead acid).

Service Instructions for AGM Batteries
When handling AGM batteries, certain special factors must be taken into consideration with regard to battery renewal and installation location:

Do not charge AGM batteries with 14.8 volts or use use rapid charging programs
When charging batteries in the "stand alone" mode, the maximum charge voltage of 14.8 volts must not be exceeded. Even briefly charging an AGM battery with a charge voltage of more than 14.8 volts (voltages usually used in rapid charge programs) will damage the battery

Do not install AGM batteries in the engine compartment
Because of large temperature variations, AGM batteries must not be installed in the engine compartment. This would result in a significant reduction in the service life of the battery

Do not open AGM batteries
By no account should AGM batteries ever be opened, as oxygen from the atmosphere would cause the battery to lose its chemical balance and cause it to fail.

Battery Replacement
An AGM battery, when installed as original equipment, must always be replaced with an AGM battery. In special cases, where a customer's driving profile (e.g. short distance driving), results in a discharged battery, the AGM battery is a recommended replacement.

Note that replacement batteries resulting from a customer's driving profile cannot be claimed under warranty.

Battery Replacement Registration

This Service Function informs the PM that the battery has been replaced. It completes the following operations:

- Battery capacity is set to 80%
- Current Odometer reading are stored. The odometer readings at which the last seven battery replacements took place can be read off from the Diagnosis Requests of Control Unit Functions
- Stored battery statistics (current, voltage , battery charge level) are deleted
- Stored temperature statistics are deleted

Hope this helps.

Only vehicle that has a PM (Power module) is the e65/e66 02-08 7 series. Just a FYI. In other vehicles e9x / e6x, the DME takes care of this info.

[BG351]

My dealer quoted prices for replacement batteries for my '06 325i as anywhere from $230 - $299, depending on type, with AGM being the highest. Also quoted 2 hours for remove / replace / register. Total cost = $430 - $530+, again battery-type dependant. The SA I spoke with stated that the car may not start if I replaced it myself until the battery was registered. Now I'm a bit concerned that I may have to tow it to the dealer if I attempt it myself. Any validity to this concern ??? I've never heard of anyone having that problem, but my luck I'd be the first.

[kaigoss69]

Originally Posted by BG351

My dealer quoted prices for replacement batteries for my '06 325i as anywhere from $230 - $299, depending on type, with AGM being the highest. Also quoted 2 hours for remove / replace / register. Total cost = $430 - $530+, again battery-type dependant. The SA I spoke with stated that the car may not start if I replaced it myself until the battery was registered. Now I'm a bit concerned that I may have to tow it to the dealer if I attempt it myself. Any validity to this concern ??? I've never heard of anyone having that problem, but my luck I'd be the first.

That is friggin' ridiculous. I'm going to say it again, my 06 330i has been doing great with the $75 Wallymart battery I put in there last spring. Took me 30 minutes to swap out. Same thing for my wife's X3, going on two years now with zero issues. Cold cranks on both cars are much better since replacement batteries both had higher CCA's than stock.

Jeez, you can lead the horse to water, but.......it may still gallop over the mountain and drink from a dirty puddle instead .

[veenay]

Hi Guys,

Will I have any issues with running a lead acid battery vs a AGM one?

I recently just purchased a battery from a third party for $150 vs the dealer price of about $500.

Dealer is suggestion to replace battery with AGM.

I been running this other battery for about 2 months now and no problem.

[Weaselboy]

Originally Posted by veenay

Hi Guys,

Will I have any issues with running a lead acid battery vs a AGM one?

I recently just purchased a battery from a third party for $150 vs the dealer price of about $500.

Dealer is suggestion to replace battery with AGM.

I been running this other battery for about 2 months now and no problem.

http://www.e90post.com/forums/showthread.php?t=378052

You already have a thread going on this.

[1seriesfan]

I had to replace the battery today in my '06 330xi. Just came to the site to see what I could learn as I remembered reading something months ago about the computer losing memory, etc. I had no clue about "battery registration" until I came here!

Anyway, the short story is that I replaced the battery with an $80 aftermarket 49 series (lead) battery and all worked well. I did have to reset the clock, and of course I lost the mileage average, but that's it. I'm not going to bother with registration or resetting via the dealer code reader anything as I am about an hour away from any dealer.

I'm with Kaigoss, I think it is all BS, especially if the dealer says the car won't start with a different battery. 12V is 12V. I really doubt there will be any problem unless the dealer reads the key next time and perhaps it recorded the fact that the voltage dropped to "0" for a short time on April 24th.

[csupernova]

man, i cant believe this thread is still running. Just go to Autozone or walmart and buy a replacement. I changed mine with one from Autozone and it has been running strong. Battery has 48 months warranty and IF my car doesn't properly charge it and shorten its life, who cares? Just bring that batt back to Autozone and get a new one. Replacing the battery is damn easy guys ! My dealer wanna charge me $350 for the batt replacement. Unbelievable !