I don't believe there is any problem with installing a non OEM battery, as
long as its a match in size/fit, and electrical characteristics.
A non BMW battery won't ruin the electrical system, but any strange quirky
electrical failures will be pointed to "That battery" by the unscrupulous
and semi unscrupulous service managers.
Thank goodness BMW doesn't sell gasoline ;) .  However, since common sense
and ethics seemed to have died at the end of the last millennia (or is
gasping its last breath), I would, if my BMW were still under warranty, bit
the bullet and buy their glutinously overpriced battery.  That being said, I
bought a replacement battery from Pep Boys for my 00 Z3, which was no longer
under warranty.  Any when my 97 528i's battery requires replacing, I intend
to buy the least expensive matching battery from BMW or Pep Boys, or Sears,
etc.

SC
00 Z3
97 528i

BMW don't make their own batteries. In the UK, Bosch branded ones are
identical but much cheaper - of course because of the dealer's mark up etc
which is vast.

ISTR that US BMW batteries are made by your namesake, Douglas.

what a ripoff. Isn't the battery covered under your warranty ?
You can probably get a cheapie for 50 dollars,and a betet rotpima
battery for 100 dollars or so.
when our 01 330 had it's battery fail around 35K it was replaced under
warranty. no cost. They even towed it to the dealer since it was
parked in my garage. Told them they could install it there but some
liability issue made them tow it. Ahwell.

On other cars I get the cheapest battery I can get. Last one I had at
Autozone. They come with a prorated warranty. Most die within 2 years
since it is in Arizona and the heat kills them.
My last battery lasted less than 2 years, and with the proration it
only cost me 15 bucks to replace a 50 dollar battery !

Remove NO-SPAM from email address when replying

For my 328, the original battery is made by Douglas.  Local Batteries Plus
stores here carry them, or can order.  I'd look for a Batteries Plus
store.

Frank

I recently replaced the battery on my 2000 328i.  As I recall, the dealer
wanted  close to $200.  When I explored it further, that number was broken down
into the cost of the batter, and they were going to check the electrical
system.  It's the unnecessary labor that added significantly to the cost in my
instance.  Is the $400 just to replace the battery, with nothing more done to
the car?

Ira

Hi Doug,

I will add my two cents.  The only thing you need to be care of is
matching the plate chemisty of the replacement battery to the OEM
charging system ((so it will be charged correctly) and meeting or
exceeding the CCA and RC cpacity of the OEM battery.  When it comes to
recharging, 12-volts is not 12-volts  and millivolts matter.  In
otherwords if you replace a Maintenance Free with a Low Maintenance
you will slighly overcharge it and have to add more water.  If you
replace a Low Maintenace with a Manitenance Free, the battery will
never obtain a full charge.  

As others have pointed out, Douglas appears to have BMW's U.S. battery
contract; however, I belive your car was made in Bavaria, so I would
look at Vatra's (which is now owned by Johnson Controls) battery
selector for the exact specs for your replacement battery.  My guess
is that they are using a Silver dymanic.  Replacing it with a
compatable Douglas would be the safest choice, but paying a dealer for
a $400 for a $75 battery is non-sense.  If it were my car, I would
consider using a sprial wound AGM battery like an Optima or Exide, if
it will fit and meet or exceed the specs, because it will give you a
greater charging window plus a dozen other advantages over a wet
battery.  If you use a Douglas replacement, that will take the dealer
out of the equation, because that is what he is probaly trying to sell
you.

In any event, if you have the time please read Section 7 in the FAQ on
www.batteryfaq.org for more information on buying batteries.  The
on-line battery selector quides are in the Battery Manufacturer and
Brand Names List on the same web site.  

Kindest regards,

BiLL......

Any good battery dealer should be able to look up your car to get both the
size and cold cranking amps (CCA) for a replacement battery.

http://tinyurl.com/2fv3u will take you to the Interstate MTP-91, as
spec'd for the 99 750iL.
Find a dealer near you, it should be just under 100.00. There is
absolutely no electrical magic about the BMW branded unit. All you need
be concerned with are dimensions, layout, and capacity, all of which are
met by the Interstate unit.

--

dkeene@mail.com (Douglas Keene, M.D.) haute in die Tasten:

Batteries for BMW are standard equipment. You have to look for the
capacity of the battery (AH=amperehours) and for the size of the unit
installed in your car. The best move would be: de-install the old battery
and take it with you to your favourite car battery dealer. Check if the
battery poles of the new battery have the same layout and diameter as the
old one had. In Germany all car batteries usually have the same
diameters, but some japanese cars use batteries with a different layout,
which makes it hard to switch to an OEM product. I do not know how usual
US batteries look like, so take your original one with you for
comparison. The voltage is standardized to 12 Volts, you will hardly find
a different voltage in a passenger car. If your battery dealer cannot
provide you with a new battery of exactly the same capacity, better take
something slightly larger than something too small. I just replaced the
62 AH battery of my 325i with a 66 AH battery from the DIY store.
Changing the battery may cause a loss of configuration data of your car
stereo and maybe a problem with your car immobilizer. You should check
how they behave when they run out of current. Keep in mind that car
batteries contains  lead and acid. So the dealer who sells the new
battery to you should take the old one and care for a proper disposal. In
Germany you have to pay a 7,50 Euro charge for that purpose.

IANAL, but I cannot imagine that an OEM battery can actually void a
warranty. It would be the same as banning tires from a 3rd source or so.

Frank