ECO Stop

[stu]

Thanks everyone

This has happened only twice this year, usually works perfectly and starts to function within a mile of home. Traffic here is slow = a side effect of the Hammersmith Bridge closure which I'm sure has it's won heavily used website.

I'll get the battery changed. It has to be a Mercedes one as the recovery people t humpy about OEM ones.

I;ll also get the voltage sensor checked. If the battery is low this function should not be triggered at all.

The specific firmware was refreshed recently.

 

[Deleted member 149005]

When it fails to restart, does it not turnover or does it turnover but not fire????

 

[stu]

Thanks Greensmanslk

Attempts to restart the car produce no sound of a starter motor having a try, but I can hear some quiet clicks as relays are activated.

Not sure if these clicks happen when the ECO restart should happen as we are not listening out for it then. (it has happened only twice, some 3 months apart)

At these points, switching everything off, getting out and locking the car before getting back in and using the starter button in the usual way with ECO stop/start off produces only these clicks. Seems to recover after about 15 minutes but this is not a situation I want for my wife on the M25.

It is a c200 sport W205.

--
Stuart

 

[markjay]

The 'clicks' are usually the starter solenoid that engages the starter motor drive with the flywheel.

But there's not enough battery power to actually turn the starter motor.

 

[mikrt]

The 'clicks' are usually the starter solenoid that engages the starter motor drive with the flywheel.

But there's not enough battery power to actually turn the starter motor.

That makes sense. But the start/stop shouldn't be functioning if it detects low battery. So I guess it's more than just poor battery. Needs to have codes read.

 

[markjay]

Might be an intermittent fault with the electronic circuit inside the starter motor?

Another thought is an intermittent fault with the inhibitor switch in the transmission. Try starting the car when it's not in P (it won't start, obviously) and see if you can hear the same ticking sound?

 

[Bobclive2]

Your problem is a near to flat battery caused by driving mainly short journeys with numerous starts with the stop/start system in play. The main reason you do not have a fully charged battery with your journey type is due to smart charging and the smart alternator. With smart charging the Engine management unit (EMU) reads the state of charge (SOC) of the battery from the sensor attached to the negative clamp of the starter battery (small 2 wire plug). Smart charging will only charge the battery up to between 75 to 80% under engine power the other 20 to 25% has to come from regeneration (braking or coasting). If there is little regeneration the battery will remain near to flat at that 75 to 80% level of charge. To get over this use a CTech or similar charger or do this and resolve the low battery and starting problem permanently.

Disconnect the sensor attached to the negative battery clamp, the EMU will now revert to a traditional continuous charging regime of between 13.8 to 14.2 volts, this will ensure the battery is near to fully charged even on short journeys. The down side to this (if you like stop/start) is this system is now permanently disabled, brake hold is also disabled which for me was and is of no concern, everything else works as it should. I never trusted brake hold and hate stop/start with a vengeance.

With the sensor disconnected there is no need to code a replacement battery as the EMU does not now know what type of battery is in the car. I have a Porsche Cayman 981 with sensor disconnect and a Dec 2011 Mercedes C-Class Coupe cgi petrol, the sensor on the Merc has been disconnected for over a year with no issues what-so-ever, even passed MOT with it disconnected. The Merc`s starter battery is original and still functions as normal.

There are NO warnings on Merc`s dash, no EML, the only indication is the stop/start icon never goes to green.

Charge the battery, disconnect the sensor and try it, if not happy just reconnect the sensor and you are back to normal.

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[stu]

Bobclive2. Wow! Talk about comprehensive. Sadly we have no ability to do things to our car ourselves nor to even charge the battery. So I am limited to dealers/independents. The car has survived 4 years of this treatment, so maybe a new one and a check on the ECU may have to suffice.

Don't get me wrong I used to do all my servicing. Big end's, building wiring looms for rally cars all in a happy days work.

 

[TonylUK]

Can you just buy an ODBC tool and o we ride the autostart and just leave it perm off. I've bought one, will be updating the system this weekend.

Sent from my SM-N976B using Tapatalk

 

[Deleted member 149005]

Why spend money buggering about with a plug in when all you need to do is switch it off ?

 

[TonylUK]

Why spend money buggering about with a plug in when all you need to do is switch it off ?

Yea but switching it off *every* time I get in the car snzzzz few quid and it's off. Problem is I always scoot off and forget. Just when I'm at a dodgy junction, stop start is on and off more times than Brexit!

Sent from my SM-N976B using Tapatalk

 

[Deleted member 149005]

‘Cos it so much more difficult than putting your seat belt on or changing radio station or plugging phone in

 

[wongl]

Yea but switching it off *every* time I get in the car snzzzz few quid and it's off. Problem is I always scoot off and forget. Just when I'm at a dodgy junction, stop start is on and off more times than Brexit!

Sent from my SM-N976B using Tapatalk

If you forget to switch off ECO Start/Stop when you drive off first thing in the morning, you can always turn it off when it kicks in the first time.

 

[Bobclive2]

Forget about the stop/start bit Stu, your short journeys leave you with a near to flat battery, you have two choices, disconnect the sensor or keep recharging your battery, a new battery will not solve this smart charging problem. Ford used to deactivate the smart system on request.
See Ford 150 forum.
The sensor in vid was from eBay cost £4.50, fits In cig
Lighter socket buy one and observe charging voltage.

 

[Bobclive2]

Compare 2 cars on the Honest John site, Slk 180 2010 against Slk 180 2012, the earlier car has no stop-start, no regeneration, fuel consumption is less than 2% improvement for later car, hardly worth the hassle.

 

[wongl]

In my opinion, the best approach to determine the benefits of ECO Start/Stop will provide is to measure the fuel consumption on a regular route (for example on a daily commute) over an extended period of time comparing the different fuel consumption with ECO Start/Stop enabled vs disabled.

I can report that on my daily commute to work with ECO start/stop disabled, my typical fuel consumption is over 15litres/100km measured over a two month period (aux battery wasn't healthy enough to support ECO start/stop). After I replaced the Aux Battery to enable ECO start/stop, my typically fuel consumption on the same route dropped to below 9litres/100km.

The car does not know about the traffic condition, so the driver must decide. I would highly recommend forum members who have an interest in ECO start/stop to experiment with this feature to determine for themselves the effectiveness on their journeys, traffic conditions and driving style. Taking a keen interest in this feature will provide an informed understanding of the benefits of ECO start/stop to allow effective decisions to enable/disable the feature rather than relying on the opinions of other members and/or sources of information. Use it if it when it provides a measurable benefit, disable it when it doesn't. Simples.

 

[Deleted member 149005]

I’ll take a 40% fuel saving over the minor inconvenience of a fraction of a second delay in moving off..

 

[wongl]

I’ll take a 40% fuel saving over the minor inconvenience of a fraction of a second delay in moving off..

Ditto, but some drivers (mostly from the USA) absolutely hate their engines being stopped causing a pause /hesitation thus interrupting their driving style. Many however would like to maintain the ‘4 cylinder’ ECO mode without the actual stopping bit.

I think MB should make this available for drivers who would prefer this to the full ECO start/stop feature.

 

[David404]

Personally I would start by giving the battery a good charge with something like a Ctek charger, with short journeys especially in cold weather it can take it's toll on batteries.

The suggestion of charging battery to 100% with a Ctec charger is sound. Batteries like to be charged to 100% occasionally to keep them in good health and an alternator is unlikely to do this.

I'd also suggest that if you have any issue that could be battery related charging the battery should be first step. MBs are notorious for electrical demand.

If you do replace the battery if possible I'd be charging the new battery to 100% before fitting.

Good luck, hope you get to the bottom of the problem.

 

[Bobclive2]

Wong, there may be times when a minority of drivers will gain some benefit from this system, you do the majority of your driving in Hong Kong therefor you appear to be one of those drivers. That gain has to be set against the hundreds of thousands of extra starts the engine and components have to endure, we know the system eats batteries and is probably causing the early timing chain failures we are now observing. In my view this is just another layer of electronics that give most drivers little benefit but can cost many hundreds of pounds when trying to diagnose and fix this complex system when it fails to work, which it often does.

Wong said, Quote Many however would like to maintain the ‘4 cylinder’ ECO mode without the actual stopping bit.Quote

It is interesting that you brought this up Wong, cylinder deactivation still works with the Mercedes SLK 55 when the battery sensor is disconnected, it does not work when there is a fault with the sensor, it`s all about doing a little research before making a statement.

Start / Stop / eco tech a load of Bull ...... see #95 comment and read Col`s thread.

GreenmanSlk said, Quote I’ll take a 40% fuel saving over the minor inconvenience of a fraction of a second delay in moving off..Quote.

MPG improvements between SLK 200 R171 v`s SLK 200 R172.

The point of this post is to try to find out what the fuel gains actually are in the real world after Mercedes fitted its Blueefficiency modifications to the SLK.

I used the SLK 200 R171 and the R172 as this car in both iterations used the same 1796 cc engine so can be compared like for like before and after, also the R171 did not have any of the fuel saving technologys fitted to the R172.
Mercedes state the blueefficiency savings are 10% between these two SLK`s.
2004-2011 auto- MPG from Honest John 31.5
R172 SLK 2011-2016 auto MPG from Honest John 32.1
Fuel gain for R172 with Blueefficiency against the R171 without is 0.6 mpg or 1.9%, that includes, direct injection, Turbo charging, stop/start and (smart charging energy regeneration which the R171 did not have.

All that tech for 1.9 actual on the road fuel gains, we also now have carbon problems on the inlet valves, expensive batteries which are failing earlier than the cheaper batteries etc.