Thread: E90s suck.
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Old 10-08-2017, 09:12 PM   #7
JST
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So I still don’t get the battery thing. If the engine’s control computer is capable of reacting to the battery as it gets older, there shouldn’t be a need to “reset” it—if the car is reacting to the battery, it should react to a new battery differently than an old one, right?

The only way a “reset” switch makes sense is if the car has a linear map of some kind that it applies to battery charging. But that’s insane, since batteries wear at different rates depending on conditions.

I think it’s a means of forcing you to go to the dealer for a new battery, pure and simple.

EDIT:

Ok, some googling yielded some additional detail:

http://bimmertips.com/bmw-battery-re...ing-explained/

Here, the allegation is that if you don't reset the battery, the car will overcharge it, damaging the battery, because it will assume that the old battery is still in the car.

But.

Haven't cars had to deal with this problem since literally the day batteries were added to cars? Doesn't every car have to have a means of determining when the battery is charged, and not overcharging it? Why would the super fancy modern electronic IBS (which doesn't stand for irritable bowel syndrome in this application) be *less* able to do this than any other alternator?

I will admit I'm not an expert on electrical systems, but this semi-plausible explanation raises more questions for me than it answers.

EDIT TO EDIT:

I'm with this guy.

Quote:
Originally Posted by some guy on Jalopnik

Why is it that my $65 AC/DC digital quick charger for the LiPO batteries in my radio control airplane and helicopters can determine current charge state, amperage, back current, and cell resistance in order to automatically optimize the charge rate and voltage of cells and packs from 2.7 to 19.2 volts in capacities of 20 to 20,000mAh (I don't remember this spec exactly, but the range is something like that...) without causing the notoriously fragile LiPO packs to have degraded life or catch on fire but BMW can't build a charging system that can figure out how to do the same with notoriously rugged AGM/Lead-Acid automotive batteries unless the dealer calibrates it?

Probably has something to do with optimizing service billing.
https://oppositelock.kinja.com/repla...ous-1681775778

Last edited by JST; 10-08-2017 at 09:28 PM.
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