My 2002 needs a new battery. In looking at the old one there is and additional plug on the side of the battery near the top.Are these special (i.e.expensive) batteries from BMW or will any battery fit that is the right size and has the right configuration of the terminals.

Regards
Fred

 

A ventilated battery is required - is that the 'extra plug' you refer to?
Size is H6 - some catalogs show H5 for the R53 'S'. The H6 is about $150+/-.

 

This is the battery I currently have in my 2006 R53. It is listed for the R53 and it fits well. There is also a vent to put the small vent tube in. You don't need a special MINI battery from the dealership.
https://www.autozone.com/batteries-s...0_160719_25698

 

So what happens if you use a regular battery without the vent?
Does it affect performance or compatibility with the electronics? In other words will the car still run?

 

I have a limited understanding of this so you may want to do some web searching to find out more. Basically, batteries give off gas (gases?) and you don't want them building up inside the car. By having a special spot to vent the gases, you can route them out of the car. When a battery is under the hood, there is enough open air that the battery can vent and the gases are dispersed. Like I said, best to read up on it.

Yes the car will run with or without the tube but I'd rather be in a car without battery gases.

 

The vent directs the gasses that are created in the battery out. I believe that is Hydrogen, that is combustible. In the trunk of a R53, it will vent into the passenger compartment. In a r50, it will vent into the engine compartment, and has more ways to get out.

 

I can understand the venting issue if the battery is in the back/trunk.(I had an MGB that was like that)
But most cars have the battery in the engine compartment. I have a truck that has 2.

 

The Mini Battery setup was designed with a vent, regardless if it's an R50 or an R53. Why try to second guess the designers when you can get a battery from any of the Auto Store with a vent at no more cost that one without? Most problems with the Mini stem from owners trying to second guess well known and respected Mini Cooper Designers and mod an already well designed auto. You want a super fast straight line car - buy a Corvette or Hemi powered Dodge Charger. If however, you want drive a fun car that can more than hold it's own in the twisties, drive a mini. That's why the SCCA puts cars in different classes. An R50 can't compare with an R53 in the straight, but can in the twisties. You want to spend more for a battery without a vent - go for it. At your peril.

 

Actually, that's not quite true. A battery with a vent is an AGM. The advantages are that they don't off-gas because they are sealed, they last a little longer AND probably most important is that they can be mounted in any position(because they are sealed). On the other hand an SFA battery( like is used in the majority of cars and trucks) is significantly cheaper than an AGM. But, as you said, to each his own.

 

Our 1st OEM battery lasted over 10 (or may be more can't remember) years and I replaced it again with an OEM unit. That was 8 years ago and she is still holding charge just fine.

Go with OEM.