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Auxiliary battery.

The Aux Battery is there to support ECO start/stop function and also the electronic brake hold function. During a start/stop cycle, when the car is stopped by the ECO function, the Aux Battery is used to power the vital electronics of the car to preserve and isolate the main battery for starting the car when the driver steps on the accelerator pedal.
 
Petrol Pete said:
Goes flat then has to be replaced frequently from what I hear :p
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That depends on driving style/journeys and if the battery is taken good care with a decent battery charger. My car is manufactured in 2011 and the Aux Battery was replaced for the first time last year (Oct 2018). The previous owner didn't bother with charging the aux battery so it it oesn't sound that often to me to have the battery replaced once in 7 years.

I have fitted quick connect CTEK charging connectors to the Aux Battery and charges the Aux battery once a month when parked at work. Hope to get more than 7 years with this approach.
 
I replaced the original MB battery on my 2006 140+K mile C55 a few months ago, it was not faulty had had shown no sign of failing despite the car sitting outside in various airport car parks (in winter) for up to 4 weeks at a time. Replacing it seemed to be the right thing to do and not tempt fate , plus I got a modern Bosch battery reduced from over £200 to half price with a 5 year warranty , so it seemed rude not to and to do it as a kind of preventative maintenance.

So cranking a big V8 for over 13 years without fault is pretty good going, and who knows how much longer it would last if I had not changed it by choice ? my car is pretty analogue but the seats and steering wheel position can still be moved with the engine off using just battery power.

I do not think any modern vehicle should rely on an external charger unless laid up for a very very long time , in which case it would be better to remove the battery from the vehicle (not always practical I know) The car should be the charger, no matter how short the journey. A car should IMHO be able to start itself on a (previously) fully charged battery after a 8 weeks of being dormant in any weather.
 
Many modern "garage queen" models come from the factory with CTEK style charge connectors
 
Petrol Pete said:
I do not think any modern vehicle should rely on an external charger unless laid up for a very very long time , in which case it would be better to remove the battery from the vehicle (not always practical I know) The car should be the charger, no matter how short the journey. A car should IMHO be able to start itself on a (previously) fully charged battery after a 8 weeks of being dormant in any weather.
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Sadly this is not the case with ECO Start/Stop which typically includes Smart Charging. Smart Charging only charges the battery to 80% upon which the charging is disabled unless the engine is on over run. In my experience, for short journeys that includes frequent starts/stops, the battery often ends up with a charge well below 80%. This, coupled with a dash cam supporting parking mode will reduce the battery life unless topped up frequently. Putting the AGM battery for a vehicle with ECO Start/Stop seems to the general recommendation from various discussions in various forums. Each to their own of course - if one has never suffered a battery with a premature life, there is no need for one to put the battery on a charger. On the other hand, if one's battery lasted only 2 to 3 years, it is reasonable for one take some additional precaution I suppose.
 
wongl said:
Sadly this is not the case with ECO Start/Stop which typically includes Smart Charging. Smart Charging only charges the battery to 80% upon which the charging is disabled unless the engine is on over run. In my experience, for short journeys that includes frequent starts/stops, the battery often ends up with a charge well below 80%. This, coupled with a dash cam supporting parking mode will reduce the battery life unless topped up frequently. Putting the AGM battery for a vehicle with ECO Start/Stop seems to the general recommendation from various discussions in various forums. Each to their own of course - if one has never suffered a battery with a premature life, there is no need for one to put the battery on a charger. On the other hand, if one's battery lasted only 2 to 3 years, it is reasonable for one take some additional precaution I suppose.[/QUOT
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No. not 'each to their own' anyone who knows anything about machinery/aircraft/cars/trains/power stations understands that once you have overcome the wearing forces of cold and inertia to get the thing started the VERY worst thing you can do is to stop it only to start it up again for no good reason.

I have no evidence of this that I can show you but my own experience would lead me to believe that the very first time stop/start 'technology' was suggested to engine design engineers they would have all looked at each other in the meeting and thought " it's not April the 1st ..is it ?"..'which nob head thought this was a good idea for engine/battery longevity' ?

They would have been forced to go along with it to 'save' the planet and soon would realise that their jobs were safe chasing a state sanctioned impossible dream, so they went along with it.

Even the Lycra lout 'holier than thou' vegan Xtension R city center cyclist knows that going through a red light is more energy efficient than stopping at it for no good reason.

No one will ever convince me that stop/starting an internal combustion engine 100 times a day is good for anything. let alone the environment.
 
Petrol Pete said:
No one will ever convince me that stop/starting an internal combustion engine 100 times a day is good for anything. let alone the environment.
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I think you misunderstood my post and the intension of 'each to their own' phrase. I am not trying to convince you or anyone that ECO start/stop is a good thing or not. Hence 'each to their own' as in each person is entitled to their own views and opinion.

For me, there is no doubt that ECO start/stop introduces some additional wear and tear to certain components in the system, but so does leaving an engine idling at a red light. We can debate about the significance of the wear and tear incurred from start/stop vs idling, but in my opinion this is a moot point since the public simply do not have sufficient facts on this (at the moment) to make a scientific call on this.

As a car owner who lives in heavily polluted city, my judgement is that the extra wear and tear from start/stop out weighs the pollution generated by idling my car at the (long) traffic lights in extremely hot condition. I do this for my conscience and on here to help other like minded members who want to restore their ECO start/stop. i am not on here to judge or convince you or others to use ECO start/stop.
 
Petrol Pete said:
No. not 'each to their own' anyone who knows anything about machinery/aircraft/cars/trains/power stations understands that once you have overcome the wearing forces of cold and inertia to get the thing started the VERY worst thing you can do is to stop it only to start it up again for no good reason.

I have no evidence of this that I can show you but my own experience would lead me to believe that the very first time stop/start 'technology' was suggested to engine design engineers they would have all looked at each other in the meeting and thought " it's not April the 1st ..is it ?"..'which nob head thought this was a good idea for engine/battery longevity' ?

They would have been forced to go along with it to 'save' the planet and soon would realise that their jobs were safe chasing a state sanctioned impossible dream, so they went along with it.

Even the Lycra lout 'holier than thou' vegan Xtension R city center cyclist knows that going through a red light is more energy efficient than stopping at it for no good reason.

No one will ever convince me that stop/starting an internal combustion engine 100 times a day is good for anything. let alone the environment.
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100 times a day?.

If the traffic was that bad on my commute i would find an alternate means of transport :)

Or is that a made up statistic to support your own preconceived view?

Batteries are generally regarded as consumable systems are coded to check a wide range of parameters which need to be satisfied in ordered for stop/stop to operate, as evidenced by the varying nature of operation. An engineer friend tells me cars are designed with an economic life of 7-10 years.

If the implementation of stop start tech means i can continue to enjoy the use of ice power for a few more years, and delay the inevitable switch to alternatives such as electric or hydrogen, bring it on i say.
 
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greenmanslk said:
100 times a day?.

If the traffic was that bad on my commute i would find an alternate means of transport :)

Or is that a made up statistic to support your own preconceived view?

Batteries are generally regarded as consumable systems are coded to check a wide range of parameters which need to be satisfied in ordered for stop/stop to operate, as evidenced by the varying nature of operation. An engineer friend tells me cars are designed with an economic life of 7-10 years.

If the implementation of stop start tech means i can continue to enjoy the use of ice power for a few more years, and delay the inevitable switch to alternatives such as electric or hydrogen, bring it on i say.
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Are you suggesting an E class MB 'Munich' taxi will not stop/start 100 times during it's working day ? Years ago when this stuff was new I picked up a hire car (Citroen I think) from CDG in Paris, unfortunately for me I had to drive into (and out of ) the city. I am sure it switched itself on and off at least that amount of times during that particular nightmare.

I agree car batteries are consumable Items, but there are people on here being forced to replace up to two (expensive) batteries that are less than 3 years old...thats good for the enviroment no doubt :rolleyes:. The few litres of fuel (emissions) saved during all those start stops offsets the manufacture and transport of a car battery every few years ??? I think not.
 
As already posted, to get rid of stop/start I disconnected the battery sensor on the neg clamp of the starter battery over a year ago not realising at the time that smart charging was also deactivated. My car is a Dec 2011 C-Class Coupe 180 with stop/start technology. Today, after letting the car rest for over 2 hours I tested both batteries with my multimeter, the starter battery showed 12.8 volts and the auxiliary battery showed 12.7 volts. As said, both stop/start and smart charging have been deactivated for over a year, both batteries are original and dated 0911, they show no signs of failing and the car starts instantly.
I purchased the car at 3 years old, stop/start has always been turned off while the car has been in my ownership, I can only presume the previous owner did the same.
 
Quote As a car owner who lives in heavily polluted city, my judgement is that the extra wear and tear from start/stop out weighs the pollution generated by idling my car at the (long) traffic lights in extremely hot condition. I do this for my conscience and on here to help other like minded members who want to restore their ECO start/stop. i am not on here to judge or convince you or others to use ECO start/stop. Quote.

Wong, Absolutely agree, I would probably do the same, the issue I have is that the system defaults to ON which and can be dangerous at junctions if the driver has forgotten to press the off button. How do you sit for long periods in extremely hot conditions with no air con.
 
Bobclive2 said:
Wong, Absolutely agree, I would probably do the same, the issue I have is that the system defaults to ON which and can be dangerous at junctions if the driver has forgotten to press the off button. How do you sit for long periods in extremely hot conditions with no air con.
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How is that dangerous?
I have stop /start on my E63, and on the rare occasion I don't disable it by pressing the ECO button on the dash (why bother disconnecting things when a press of the button does the same thing?) and the engine stops, it starts instantanously I release the brake. No danger there that I can see?
 
Quote How is that dangerous? Quote

IT`s dangerous because, when you need to access as I do from a side road into a very busy junction of fast flowing traffic you expect (ABSOLUTELY, NO HESITATION), if you forget (and I have) to deactivate auto stop/start and feel that hesitation as you floor the accelerator your first thought would be, has the engine stalled, do I keep going or slam on the brakes, I can assure you this is not a pleasant experience and any hesitation at that point could cause an accident with oncoming traffic or you could be rear ended from suddenly stopping without warning, this could never happen pre stop/start or if stop/start defaulted to off. I have been driving for over 50 years and the only time I have experienced that feeling is with stop/start.
 
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