On my E92 320d first signs the battery had gone were stop start failed, rear window demist failed and clock would reset after 2 weeks.
Ah, understood. I wasn’t aware of your issues with the stop/start function.
Hope you get it sorted.data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
The BMS (battery management system) will lock out start/stop when it sees the battery is low. It can mean the battery is going or just that it needs a decent charge. Beware of attaching the charger directly to both battery terminals as the BMS won’t see the charge.
The car does not need coding if you keep 12v to the car while you change the battery.
what sort of journeys do you do? if they are all short it could be the battery is never given a chance to fully recharge after the initial drain of starting the engine in winter and a recharge of the battery will suffice.
Are other systems in the car shutting down at all?
euro car parts are always doing sales they were 45-50% off batteries recently just keep an eye out
How does that work?
Coding??? Say what! For changing a battery? That's a new one. Never recoded after a battery change.
see:BMW battery registering & programming explained - BIMMERtips.com
Perhaps he's thinking of maintaining the current to a car radio so you don't need to find then re-enter it's security code?
It does need coding as the IBS has different profiles for new and old batteries. You also need to code if the battery ah have changed. Put a new battery in without coding and it'll be dead after a couple years, well documented on e90post.
Yup. The car needs to know that the battery has been replaced with a new one so that it’ll be charges correctly. The software assumes a battery will lose its capacity over time and thus reduces the charge applied. Also, you may fit a larger capacity battery than standard and thus may need to increase the charge the software supplies.