BMW 320D new battery needed?

un1eash

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.

The Dreamer

Ah, understood. I wasn’t aware of your issues with the stop/start function.

Hope you get it sorted.

Atavus

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.

its_all_Greek

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

mjn

How does that work?

stblob

Coding??? Say what! For changing a battery? That's a new one. Never recoded after a battery change.

IronGiant

see:  BMW battery registering & programming explained - BIMMERtips.com

IronGiant

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?

un1eash

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.

mjn

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.