Good day.
This is my first forum post, although I've been a member for a while. Please bear with me.
My first battery in my E89 3.5i is due for replacement. The car was built in 2011, meaning the original BMW AGM battery from Exide lasted a (record-breaking?) 14 years. I haven't had any interruptions or electrical problems in the car recently. Nevertheless, I checked the battery with a Topdon BT 200 tester because I was getting increasingly nervous about its lifespan ;-). The tester's display reads: "Replacement."
My background: I'm a strict fair-weather, weekend driver who, in the past, has had very little time to drive the Z4. It currently has about 10,000 km on the odometer. The vehicle is stored for the winter.
Regardless of the season, every two months, the original BMW AGM battery was connected to a CTEK Multi XS 7000 charger overnight and charged directly via the battery terminals in AGM mode. I connected the battery terminals with a CTEK Indicator Eyelet cable for a more convenient connection. I had no problems with the Intelligent Battery Sensor (IBS) as a result.
Like other forum participants, I believe that this charging cycle, combined with the Novitec Megapulse installed from the start, has caused the battery to age so much. The photo clearly shows my self-constructed setup.
The new battery will be a Varta Silver Dynamic AGM E39 (70Ah, 760A). Unfortunately, there isn't a BMW workshop near me in my new hometown of Hungary. Therefore, I'll replace the battery myself by connecting the CTEK with the supply function to the connection/bridging points in the engine compartment to avoid any potential loss of data from the control units when disconnecting. I won't be programming or registering the new, identical battery in the system for now. If anything, I'll get the BimmerLink and code for that. Carly's subscription system is too rude for me.
I hope the knowledge I've acquired through reading the forum and watching YouTube videos is sufficient to replace the battery. However, I'm very grateful for any suggestions for improvement.