The closest battery commonly available to fit the 2002tii and 2002turbo is the Group 26. Yet, while the dimensions and posts are in the right places, the base and its feet are not and the original hold down does not work.
Importing proper batteries from Europe is out of the question as the US government doesn’t allow them unless they come attached to cars. I’ve even tried to organize a group buy of dry (fill with acid when they get here) with no luck or interest on either end.
There are but three battery manufacturers that supply the US. They’re Johnson Controls, Exide and Deka. None of the three make a proper battery for our cars, and hold a monopoly on the market.
The second generation new MINIs, R56 chassis, comes with a perfect battery, but the replacement is a larger Group 47.
One positive though, are independent battery companies, of which fewer and fewer still exist. These are mostly manufactures of marine batteries, since boats are usually much older than cars and have some very custom battery size requirements. One local to the San Francisco Bay Area that I have seen a perfect replacement MINI battery is Arc Battery Co in Sausalito. I haven’t had the opportunity to call on them to make a battery for a customer Tii, yet.
Another option is the one my father and I found for his Tii. A factory Mercedes front starter battery for an ‘08 CL500 auch as this Interstate MTP-V4. The V4 is not as tall, and s little shorter on the one end of the hold down. Yes fitment isn’t prefect, but it’s close enough without the effort of tracking down anything else. A 2002 or E21 hold down fits well. I have not tried the original Tii hold down.
https://www.interstatebatteries.com/products/mtp-v4
Hope This Helps,
Tom