Quote:
Originally Posted by fmc000
From BMW, let's assume they know their cars. BTW, I just had my battery replaced by BMW with an identical model and they registered and coded the new battery, as expected.
|
I have no doubt BMW knows their cars. They also have a desire to make money. It cost me ~$110 for a new battery (with free 3 year replacement and prorated to 5 year warranty) and ~15 minutes to install it. BMW charges ~4 times that much to replace the battery.
I've read that BMW's battery charging scheme is done to extend the life of he battery. I'm not sure that I buy that. BMW needs the battery to last 3 years to get through the warranty period so they don't have to replace it on their $. After 3 years, the quicker it fails the more $ BMW makes.
I work with large lead-acid batteries (125 VDC banks) in a nuclear power station. These batteries typically last ~20 years. We never alter the charge rate (constant voltage charging) on the batteries except following a discharge test done every 18 months where we do a high rate equalize charge to restore the battery to full capacity. We also have a large population of 12V AGM batteries similar to auto batteries throughout the plant. They are replaced approximately every 5 years and the charge rate on these batteries is constant throughout the life of the battery.
I can see the benefit of altering the charging voltage (via coding I presume) if you are switching from a conventional vented lead-acid battery to a sealed valve-regulated lead-acid (VLRA) absorbed glass mat (AGM) battery. AGM batteries are much more sensitive to overcharging and prone to dryout and possible thermal runaway if overcharged. Standard vented lead-acid batteries are much more forgiving of charging voltage.