battery madness

Ron07x5 · #1 09-19-2016, 07:49 PM

So someone tell me if you disconnect your battery for 48 hours will ia e70 forget the battery registration? My theory is my x5 fried my AGM BMW battery in a few months after doing just that! I will be getting a carly scantool to find out if I am not regostered and to register a new differnent battery.

So it seems BMW wants to as quickly as possible charge a battery based on the AH rating of the registered battery and when you lose that registration the BMW system overcharges at max? yikes! Seems BMWs fear is not having the juice to run the fans to cool expensive turbos when someone is doing just short trips to the grocery store?

AGMs do not have much acid-fluid and lead-acid have more, so cheaper lead-acid can handle being overcharged better than Agm bmw batteries.

So My plan is to get a slarge as possible lead-acid group 95r and register it as having two thirds the amp hours it does, this to get the BMW charging system to treat it nice, Live long and prosper is what I say! Then once a month charge the battery and it better not take long before I see a full charge.

So what do you think?

ard · #2 09-19-2016, 11:05 PM

Quote:

Originally Posted by Ron07x5

So what do you think?

I think you have some really bad info....

Ron07x5 · #3 09-20-2016, 09:09 AM

Quote:

Originally Posted by ard

I think you have some really bad info....

My brother was "battery czar" for los angeles water and power for two years .. he has been a consultant to my battery issue. But until I can see (by scantool) my registration of battery is lost I can't be sure. I will get that soon and then have another piece of the puzzle.

So I post here seeking more information, and you post I have "bad information" but do not cite what information is bad or why. So Ard you comment doesn't help me or anyone with "good information"

ard · #4 09-20-2016, 01:14 PM

Quote:

Originally Posted by Ron07x5

My brother was "battery czar" for los angeles water and power for two years .. he has been a consultant to my battery issue. But until I can see (by scantool) my registration of battery is lost I can't be sure. I will get that soon and then have another piece of the puzzle.

So I post here seeking more information, and you post I have "bad information" but do not cite what information is bad or why. So Ard you comment doesn't help me or anyone with "good information"

http://www.xoutpost.com/bmw-sav-foru...ml#post1061301

https://drive.google.com/drive/folde...VQ1c1dLQ3hYVFE

http://www.xoutpost.com/bmw-sav-foru...ml#post1041024

I particularly recommend the BMW documents on their charging system (in the google drive)- energy management. Send it to your consutant, see if that is how LA does theirs!

I will add that an alternator that is dying- perhaps putting out 1/2 what it should- or a car that never gets driven long enough (so called 'short trip' use) or a car that has a parasitic drain every night, will result in a battery that never gets fully charged and eventually is killed young... this seems to be the pattern we see in the E70.

davidmaria1 · #5 09-20-2016, 01:48 PM

Fan cooled turbos?

smassey321 · #6 09-20-2016, 05:06 PM

Did your X5 come with a AGM battery? Mine did not and I had to code it to let it know I was putting an AGM in.

josiahg52 · #7 09-20-2016, 08:25 PM

AGM cells are more resistant to damage from overcharge than flooded lead acid cells. They are much tougher than FLA cells. You're charging system would have to be operating far, so far outside capacity for a very, very long time to damage an AGM battery. Long before the AGM battery is damaged, the liquid electrolyte in an FLA battery would have been lost due to electrolysis and vaporization.

Both flooded and AGM cells use sulfuric acid as electrolyte.

As stated above, not all X5s came with AGM batteries and flooded lead acid batteries are available for the X5. What's in your X5?

The charge profiles and end of charge voltages are different for each type of cell.

Frequent under or partial charging of both types of cells reduces their service. Periods of open circuit in an under or partial charged condition is severely detrimental to both types of cells. Cells subjected to such abuse can usually be recovered with some careful work.

I've worked with lead acid cells and batteries for almost 20 years. From the standard 12V SLI and deep cycle batteries to 2V cells that weigh two tons each, AGM, gel, FLA, VRLA, vented, sealed, etc.

Just Looking · #8 09-21-2016, 04:23 PM

Quote:

Originally Posted by josiahg52

AGM cells are more resistant to damage from overcharge than flooded lead acid cells. They are much tougher than FLA cells. You're charging system would have to be operating far, so far outside capacity for a very, very long time to damage an AGM battery.

I have a new AGM battery installed but not registered yet. Should I be concerned about the upcoming 25 hours of freeway driving that the alternator will be over-charging the battery?

Thanks in advance for sharing your expertise.

josiahg52 · #9 09-21-2016, 05:03 PM

Quote:

Originally Posted by Just Looking

I have a new AGM battery installed but not registered yet. Should I be concerned about the upcoming 25 hours of freeway driving that the alternator will be over-charging the battery?

Thanks in advance for sharing your expertise.

I would not be. That being said, I don't know how the charging system operates in our X5s. Does it look for a certain current value at a set voltage or is it a simple matter of charging back a certain number of ampere-hours at a programmed charge voltage. If the latter, I would not be worried in the least where relatively there is some small risk involved with the former method. In either case, 25 hours should show little affect to the life of the battery.

In short, I don't think this "stupid" charging system is capable of "frying" a battery unless there is a defective or malfunctioning part. Certainly optimized charge profiles for the battery type will maximize the life of the battery by maybe +/- one year. For a battery that already has a lot going against, that's hardly noticeable. Surely if you're going through battery/ies at less than four year intervals, something is wrong.

The FLA battery in my M5 is an OE BMW battery by Exide is nine years old and has never given me an issue. I've noticed that in the last three years capacity has dropped about 9% but it still provides enough cranking amps for me to feel comfortable leaving it installed. Besides ,the M5 is a summer car and I don't sit around with the ignition on and engine off. .

On the other hand, the AGM Red Top Optima battery by Johnson Controls in my Tahoe has been in there since 2008 and still routinely tests out very close to 100% and provides ample cranking amps. I've been given many "bad" AGM batteries which I have recovered to 100% capacity. The AGM design is robust and resistant to damage. Is it the best? I don't think it's as cut and dry as that. Johnson Controls and the Interstate Megatron batteries are FLA and they are superbly exceptional.

Just Looking · #10 09-21-2016, 09:47 PM

Thanks for the information. It is helpful.

As reference, my last battery was slightly less than 6 years old when I changed it. It still worked fine but given the long road trip ahead, I did the replacement out of precaution.

I attempted to register the new battery via INPA but to no avail. Glad to hear that the risk of over-charging is somewhat bearable.