BMW ED model owners - Battery life?

Bubo · 25 Feb 2011 at 10:11

To anyone with an efficient dynamics model BM, specifically with start stop, what has your experience been with your battery life?

To put this into context I've noticed that since about christmas time the start stop function of my car has seemed to stop activating towards the end of the week. I.e. the car will get good long runs all weekend, then will get relatively short town runs during the week for work. Start/stop will work as expected for say Mon/Tues/Weds, but by thurs/friday it will stop coming on. Coincidentally I've just had my first bulb go, one of the rear brake lights, but I'm not yet getting any battery level or charging warnings. The car is about three and a half years old now.

Looking for experience of anyone here who may be able to say this is a sure sign of the battery on its way out, or perhaps a problem with the alternator, before I take it in to be looked at.

Firestar_3x · 25 Feb 2011 at 10:22

Must have a battery voltage system fitted, lots of short runs plus turning the car on and off quickly drains a battery, got get yourself a cheap battery tester and see what the condition of the battery is like.

I dislike this stop and start technology, means extra wear and tear on things like the starter motor and things will break sooner, but hey it cuts CO2 by a fraction.... But i suppose all that goes out the window if you factor in the CO2 output to build you the new components that will wear out sooner......

Wicksta · 25 Feb 2011 at 10:27

I do really short runs most weekdays (about 2 miles each way) over the winter and I've had to charge the battery once in a year, last December. Car is a 530i ED.

It didn't break down but I noticed it was turning over slowly, and the last time before charging I got a picture of a car on a ramp on the OBC. Also the clock reset.

Dandle · 25 Feb 2011 at 20:10

ED cars come with AGM batteries which are designed for deep cycle charging. Stop-start will stop working when the intelligent battery monitor detects that the battery hasn't been charged enough to use it. If you cars having at least one good run a week it should operate fine without disabling the system. It could be that you need to give the battery a good charge or something else like the IBM failing as they aren't infallible.

Twedd17 · 2 Mar 2011 at 16:40

I have a 120D ED 2007. I'm assuming you're referring to stopping for a short period of time i.e. at a set of traffic lights.

To be fair I experience the same thing but don't attribute it to the battery. I have noticed that if your routine service light comes on then ED kicks in less frequently and also if it's cold outside (frost light on) it doesn't kick in very much at all even if the engine has warmed up.

With the assumption that your car starts fine 1st time everytime and doesn't struggle to do so then IMO there is little to worry about.

Muncher · 2 Mar 2011 at 17:18

My Dad's 320ED doesn't work for much of winter, it's certainly temperature related in part.

Jonnycoupe · 2 Mar 2011 at 17:22

My Honda doesnt auto stop below 5C, its in order to maintain coolant temps in order to provide cabin heater when stopped for long periods. I assume the EDs BMWs also have a electric coolant pump or a seperate heater pump to keep coolant flowing when the engine is off aswell.

denon · 2 Mar 2011 at 18:13

there is a list of conditions to be met before the start stop works on a bmw, pretty sure it will be in your handbook

off the top of my head

drivers seat belt on
outside temp above 3C
enough brake vaccum
engine not in start up phase
battery atleast (think its 60% charged)
aircon not on to high

plenty more aswell

Dabbles · 2 Mar 2011 at 18:20

I bet it isn't environmentally friendly having to produce all the batteries that will be needed to replace those in start/stop cars.

Also, what happens when your car gets a bit older and it takes a bit of persuasion to start, do you sit at the lights with the car trying to start itself with a queue of angry people behind you?

PMKeates · 2 Mar 2011 at 18:37

Dabbles said:
Also, what happens when your car gets a bit older and it takes a bit of persuasion to start, do you sit at the lights with the car trying to start itself with a queue of angry people behind you?

That doesn't really happen to modern cars. I have a 10 year old nearly 190,000 mile BMW engine, and it starts on first churn when it's negative temps out.

Jonnycoupe · 2 Mar 2011 at 18:53

Dabbles said:
I bet it isn't environmentally friendly having to produce all the batteries that will be needed to replace those in start/stop cars.

Also, what happens when your car gets a bit older and it takes a bit of persuasion to start, do you sit at the lights with the car trying to start itself with a queue of angry people behind you?

A bit of cycling isnt a bad thing for a battery, these also have intelligent alternators so overcharging is less likely.

If your car is struggling to start when at operating temp just press the disable button and get the damn thing serviced.

Dandle · 2 Mar 2011 at 19:16

Dabbles said:
I bet it isn't environmentally friendly having to produce all the batteries that will be needed to replace those in start/stop cars.

The batteries are Absorbed Glass Matt batteries and they are designed for deep cycling. It wont hurt them like it would if you had a lead acid battery.

Trifid · 2 Mar 2011 at 19:27

Muncher said:
My Dad's 320ED doesn't work for much of winter, it's certainly temperature related in part.

It doesn't turn the engine off if it is below operating temperature, low battery charge, high electrical draw or if it is below 3*C outside.

mattyprice4004 · 2 Mar 2011 at 20:10

Dabbles said:
Also, what happens when your car gets a bit older and it takes a bit of persuasion to start, do you sit at the lights with the car trying to start itself with a queue of angry people behind you?

I have a 200,000 mile old Rover and that doesn't even do it. How old are you talking?!