START STOP

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I've just received my CTEK MXS 5.0 from Amazon. It's charging my car battery right now. The instructions are a bit vague - I couldn't decide whether to set it to "normal battery programme" (for use with a wide range of batteries, including "many AGM batteries") or the "AGM option" (for "charging most AGM batteries"). I've assumed I have an AGM battery because I have start/stop and it's too bloomin cold to stand outside fiddling with taking the battery cover off to have a look. I've set the charger to AGM mode and all appears ok for now.

BTW, I haven't noticed whether or not the start/stop is working lately. All my journeys in the last couple of months have been too short to expect it.
Yes your car is very likely AGM. My 2007 ML is even AGM! However stop-start is a good indicator of an AGM battery. Don't use the regeneration mode on an AGM battery though, even though it will let you.

I'm not a battery expert but CTEK told me that regenerating an AGM - or using the normal battery programme - once or twice won't damage the battery but you shouldn't do it repeatedly. Using a Lithium battery charger on a normal or AGM battery (and vice-versa) is a definite no-no though, or so CTEK told me.
 
Thanks for the info and will be sure to check that any charger will have this option. I don't usually have the air con on, in fact, I rarely have it on as I don't like to use fuel if I don't need to (sooner open the windows or open the roof!).
I'm confident that the s/s failing to turn on/off is not a fault but perhaps just a top up to the battery is all that is required. MB is going to sting me of £110 to find out but either way, hopefully I should get the solution from that. Cheers
I don't think that having the air con on makes any difference to the fuel consumption on modern cars with engines larger than 1 litre. Other than trying it out a couple of times to see if there was any difference (there wasn't) I haven't turned off the A/C in any car for over 20 years. The potential repair costs caused by turning it off are real and not worth it. As already mentioned, windows demist much faster when the A/C is on. In fact, other than the brief tests I referred to earlier, I can't even remember when I last touched any of the climate controls in my last two Mercedes - it's so good I can just leave it alone and let it automatically set everything.
 
How much is this Halfords ( Yuasa ) battery ?
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How much is this Halfords ( Yuasa ) battery ?
Really at a loss of what to but and from where !?
Personally I wouldn't change the battery or pay for diagnostics until I had reconditioned (posh word for recharged) the battery. Batteries do get stretched at this time of year - especially in the current climate - and just because a battery is low, it needn't be replaced. The main dealer will probably diagnose low voltage and replace the battery without checking whether it's healthy.

So I would recondition/recharge it first. If that fixes it then I would wait and see if fault returns, and in what timeframe, and if it returns quickly then I would replace the battery. Personally I wouldn't pay for diagnostics until the final step, because it's highly likely to be the battery, and then it's likely that recharging it will kick your stop-start back into life.

I'm not far away, and so as I mentioned before I'm happy to arrange for someone to bring you one of my CTEK MX5.0 conditioners.
HI, thank you for your kind gesture of help. I am at a loss of what to do, take it to main dealers, get a diagnostic (which may or may not find the issue - assuming a low battery) or go ahead an get a new battery. Halfords have quoted £167 which seems reasonable and Mercedes have just quoted £212.00 but I don't know if that includes fitting. Its so confusing what is the best way forward. Could I take you up on your offer... what do I need to do ? Many thanks
 
Yes your car is very likely AGM. My 2007 ML is even AGM! However stop-start is a good indicator of an AGM battery. Don't use the regeneration mode on an AGM battery though, even though it will let you.

I'm not a battery expert but CTEK told me that regenerating an AGM - or using the normal battery programme - once or twice won't damage the battery but you shouldn't do it repeatedly. Using a Lithium battery charger on a normal or AGM battery (and vice-versa) is a definite no-no though, or so CTEK told me.
Thanks Rob. I'd been using an old coal driven charger for years without any apparent ill effects. The sad old thing never managed any more than a trickle charge that barely dragged the ammeter needle off zero so probably not capable of doing any harm.
 
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Really at a loss of what to but and from where !?

HI, thank you for your kind gesture of help. I am at a loss of what to do, take it to main dealers, get a diagnostic (which may or may not find the issue - assuming a low battery) or go ahead an get a new battery. Halfords have quoted £167 which seems reasonable and Mercedes have just quoted £212.00 but I don't know if that includes fitting. Its so confusing what is the best way forward. Could I take you up on your offer... what do I need to do ? Many thanks
At £212, if they'll fit it then I would go with Mercedes rather than Halfords. Not sure where it is on your car, but if it's under the seats it can be a nightmare. I would ask them for a discount, and then ask them to fit it.

Might be able to meet you somewhere this evening - perhaps around 1930-2000 ish - if I can, would that work for you? I can't send you a private message yet (you have insufficient privileges) so keep an eye on this thread.
 
At £212, if they'll fit it then I would go with Mercedes rather than Halfords. Not sure where it is on your car, but if it's under the seats it can be a nightmare. I would ask them for a discount, and then ask them to fit it.

Might be able to meet you somewhere this evening - perhaps around 1930-2000 ish - if I can, would that work for you? I can't send you a private message yet (you have insufficient privileges) so keep an eye on this thread.
HI, I just spoke to MB - they charge extra for fitting so probably looking a round £300 or so. No problem for me at that time, I can meet you in Lichfield if it helps.
 
HI, I just spoke to MB - they charge extra for fitting so probably looking a round £300 or so. No problem for me at that time, I can meet you in Lichfield if it helps.
Apologies, I need to watch the announcement this evening. We’ll try and sort out another time. At £70 you won’t regret buying one but mindful that if there’s another fault it’s £70 on top of the cost fixing.
 
HI, I just spoke to MB - they charge extra for fitting so probably looking a round £300 or so. No problem for me at that time, I can meet you in Lichfield if it helps.
Have you seen my post on Stop/Start
 
OP , Boris has just saved you a lump of money by locking the country down so MB will not be able to rob you next week (this time) , the stop/start not working is no big deal and certainly not (in my opinion) something worth spending money on to fix. If it was that important MB would have designed the function properly in the first place , it's just an engineering box ticking exercise to meet emission regulations.

As said here by others , run your climate control ALL of the time.
 
Our 2019 C300 (on just over 6000 miles) has the same issue - the Mercedes Me app shows the battery status as 'partially charged' at all times, even after a 200 mile trip. So either the battery is degraded or there's something wrong with the way the voltage is being measured. It's being looked at under warranty in a couple of weeks.

New battery fitted today (FOC) ... the first one only lasted 18 months! 😮
 
First of all I’m a great fan with the Ctek charger, I have one coupled up to the SL all the time when it’s parked up.
However one of the very few annoying things on the CLS is the stop start system.
Perhaps useful in city traffic but no use IMO where I live and it’s one of things I switch off every time (if I remember) when I get into the car.
On my car it can switch off the engine when pulling up at a junction and reversing back to execute a turn.
 
However one of the very few annoying things on the CLS is the stop start system.
Perhaps useful in city traffic but no use IMO where I live and it’s one of things I switch off every time (if I remember) when I get into the car.
On my car it can switch off the engine when pulling up at a junction and reversing back to execute a turn.

I suspect it may be better with petrol engines than diesels ... they seem to start more 'instantly'. On the few occasions it worked on our C300 I didn't find it intrusive, but I think it's more noticeable on the newer GLC 300d courtesy car I have at the moment. There's a tiny bit more lag each time the engine restarts.
 
Yep, seems to be in the boot but I still don't know if its that which is the cause. I will speak to MB as the car is fully serviced (most recent only 1000 miles ago) and see what they say. May be battery or just a software issue - either way they should be able to help. Thanks
You get a warning on the dash.... Aux batt malfunction.... When the battery's no good. I had mine replaced, start stop is always erratic, sometimes works from cold, sometimes after 30 plus miles. I just turn it off.
 
Hi,

I am the proud owner of a Mercedes 2017 250d C Class Convertible.

I purchased the car on October 2020 and has 26,000 on the clock. Ever since I have had the car, the auto start stop function isn’t working. The light always stays yellow around the A in the dashboard and not changing the green. I’ve taken both long and short drives on good weather days (not to hot and not to cold) but still no change

From hear say, it could be either of the batteries but I am unsure what other battery there is other than the main batterie (or where this second battery may be).

Does anyone have any suggestions please ?

Many thanks and Happy Christmas and New Year !
Hi, I own a GLC 350D and recently had the same problem. Remembered the solution from my old Mondeo days. Yesterday I took her out on the motorway, Selected S+ and drove for about 30-45 mins. The key is to have the engine running at about at 2,000 revs during that time. Also make sure your timing belt/chain are ok. Got up this morning and stop/start now working fine. Hope that helps.
 
But what if this so called ECO feature was a bad thing... a mechanical & electrical wrecking ball , what exactly would you be fixing then ?
 
You get a warning on the dash.... Aux batt malfunction.... When the battery's no good. I had mine replaced, start stop is always erratic, sometimes works from cold, sometimes after 30 plus miles. I just turn it off.
Not with a C250d from 2017 you won't.
It doesn't have an auxilliary battery, it uses a capacitor that sits behind the glove box. It's a common part to fail and does not give any warnings when it does. Mine was replaced under warranty when the stop/start failed, that fixed it at the time but 18 months later the main battery had to be replaced when stop/start failed again. Never once did any battery warnings show on the dash.
 
Hi, I own a GLC 350D and recently had the same problem. Remembered the solution from my old Mondeo days. Yesterday I took her out on the motorway, Selected S+ and drove for about 30-45 mins. The key is to have the engine running at about at 2,000 revs during that time. Also make sure your timing belt/chain are ok. Got up this morning and stop/start now working fine. Hope that helps.
Thanks for the tip, will take it on a good run..... once we are out of lock-down !! Cheers
 
Thanks for the tip, will take it on a good run..... once we are out of lock-down !! Cheers
I can assure you it will not work on your car if the battery or capacitor is at fault. My battery was slightly less than 100% perfect and despite using it daily for three whole weeks on long runs the stop/start still never worked. After replacing the battery, it started to work again.
On your car, if either the capacitor or main battery are less than 100%, your stop/start will never work.
 

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